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1

The Model 835-IEEE Interface is designed to enhance the capabilities of theModel 835 Laser Pico-Watt Digital Power Meter by allowing the transmis-sion of data and commands over an IEEE-488 bus in computer controlledinstrumentation systems. The Model 835-IEEE Interface provides all thedigital logic necessary to interface the Model 835 to the bus using standardIEEE-488 (1978 standard).

1. Section 1 contains general information and guidelines for using thismanual.

2. Section 2 is an overview (general descriptive, functional and useinformation) of the IEEE-488 (1978 Standard) Bus, with which theNewport Model 835 Laser Pico-Watt Digital Power Meter (equippedwith the Model 835-IEEE Interface) is used - in a Computer ControlledInstrumentation System.

3. Section 3 contains detailed operation and use information for the Model835 power meter, equipped with a Model 835 interface.

4. Section 4 provides theory of operation, and Section 5 contains mainte-nance information, for the Model 835-IEEE Interface.

Introduction

The Model 835-IEEE Interface was carefully inspected both mechanicallyand electrically before shipment. Upon receiving the Model 835-IEEEInterface, carefully check all items for any obvious signs of physical damageduring shipment. Report any damage to the shipping agent immediately.Retain the original packing materials in case reshipment is necessary. Thefollowing items are shipped with every 835-IEEE Interface order:

Model 835-IEEE-488 Interface*

Installation Hardware (complete)*

Modified Rear Panel with Power Cord*

Model 835-IEEE-488 Interface Instruction Manual

Additional Accessories (as ordered)

If an additional instruction manual is required, order the manual package(Newport Corporation part number 14077-01). (The manual packageincludes an instruction manual and all pertinent addenda.)

*If the interface is ordered with the Model 835, the parts marked with * willbe installed in the main unit.

Unpacking AndInspection

Preparation For Use

As shipped, the Model 835interface is set to the addressable mode, with the primary address set to 22at the factory. For information on changing these parameters, refer toSection 3. If the Model 835-IEEE interface is to be field installed, refer toSection 5 for installation instructions.

SpecificationsModel 835-IEEE Interface specifications immediately precede this section.

1.3

1.1

1.2

1.4

Section 1General Information

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2

symbols and terms are used in this manual and found on the Model 835:

The ! symbol on the instrument indicates that the user is to refer to theoperating instructions.

The WARNING headings in this manual explains danger that could result inpersonal injury or death.

The CAUTION headings emphasize hazards that could damage the instru-ment.

The NOTE headings highlight information or procedures especially beneficialor useful.

inside the front cover of this manual. For warranty service, contact yournearest Newport representative or the factory to determine the proper courseof action. Newport Corporation maintains service facilities in the UnitedStates, West Germany, and England. Addresses for these facilities are on thewarranty page of this manual. Direct questions on application, operation orservice of your instrument to the Newport representative at any of theselocations.

Warranty Information

Warranty information is1.5

ments or changes to the interface, which occur after this manual is printed areon an Addendum sheet included with this manual. Review these changesbefore attempting to install or use the interface.

Manual Addenda

Information on improve-1.6

Safety Symbols,Terms, And Notes

The following safety1.7 ∆

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3

The IEEE-488 bus is an instrumentation data bus standardized by the Instituteof Electronic and Electrical Engineers (IEEE) in 1975. The most recent revisionof bus standards was made in 1978; hence the complete description forcurrent bus standards is the IEEE-488 (1978 Standard).

This section gives a brief description of the general bus structure with anoutline of bus commands. The information presented here is not intended tobe an in-depth description of a very complex standard. More completeinformation on the IEEE-488 bus, also frequently referred to as the GeneralPurpose Interface Bus (GPIB), is available from the IEEE and a variety of othersources.

Introduction

2.1

designed for parallel data transfer between devices to optimize data transferusing a minimum number of bus lines. The bus has eight data lines that areused for both data and some commands. Five additional bus managementlines and three handshake lines complete the bus (a total of 16 signal lines).Since it is a parallel bus, all devices connected to the bus have the sameinformation available simultaneously. Exactly what is done with the informa-tion by each device depends on many factors, including device capabilities.Each connected device uses or reacts to the information depending on devicecapabilities and other factors.

For controlled operation, see a typical bus configuration in Figure 2-1. Thetypical system has one controller and one or more instruments to whichcommands are given, and in most cases, from which data is received. Gener-ally, there are three categories that describe device operation: controller;talker; listener.

The controller does what its name implies: it controls other devices on the bus.A talker sends data, and a listener receives data. Depending on the instru-ment, a particular device may be a talker only, or both a talker and a listener.The Model 835, through the 835-IEEE interface, is capable of both talking andlistening - but it does not have controller capability.

A system usually has only one controller (control may be passed to an appro-priate device through a special command), but any number of talkers orlisteners may be connected within the hardware limits of the bus. Generally,bus operation is limited to use with a maximum of 15 devices. This numbermay be less - if higher than normal data transfer rates are required, or iflonger than normal cables are used.

Several devices may be commanded to listen at once, but only one device maybe a talker at any given time. Otherwise, communications would bescrambled much like an individual trying to pick out a single conversation ina large crowd.

Before a device can talk or listen, it must be correctly addressed. Devices areselected by their primary address. To avoid confusion, the addressed deviceis sent a talk or listen command with its primary address. Normally, eachdevice on the bus has a unique primary address and each may be addressedindividually. The primary address of the Model 835 interface is set to 22 atthe factory, but it may be changed to any other between 0 and 30 (Section 3).

Once the device is addressed to talk or listen, designated bus transactions takeplace. For example, if the Model 835 is addressed and commanded to talk, itwill generate and place its output data string on the bus - one byte at a time.

Description

The IEEE-488 bus was2.2

Section 2

An Overview of the IEEE-488 Bus


4

The controller then reads and uses this information, and/or directs any otherdevice(s) selected to read or use the data - at the desired device location(s) onthe bus. Other bus functions and instrumentation may be controlled byspecial bus commands (paragraph 2.3).

IEEE-488 bus are grouped into three general categories. The data lines handlebus information, while the handshake and bus management lines ensureproper bus operation and correct data transfer. Each of the bus lines operatein an inverted state (low is true). The purpose of these lines (shown in Figure2-1) are described in the following paragraphs.

IEEE-488 Bus Lines

The signal lines on the2.3

2.3.2 Handshake Lines


5

2.3.1 Bus Management Lines

Five bus management signal lines transfer specific single-line bus commands,which ensures orderly transfer of data between devices. These lines transferonly the single-line commands described in paragraph 2.4.

1. ATN (Attention)-The attention line is an important management line. Thestate of the ATN line indicates whether information to be on the data bus isdata or a command (paragraph 2.4).

2. IFC (Interface Clear)-Setting the IFC line true (low) causes a bus interfaceclear status by sending the IFC command.

3. REN (Remote Enable)-Setting the REN line sends the REN command. Thissets up instruments on the bus for remote operation.

4. EOI (End or Identify)-The EOI line is used to terminate a multi-bytetransfer sequence.

5. SRQ (Service Request)-The SRQ line is set low by a device on the bus,when that device requires service from the controller.

Figure 2-1. Typical IEEE-448 Bus Configuration

This ensures reliable data transfer regardless of the transfer rate. Generally,data transfer occurs at a rate determined by the slowest active device on thebus.

One of the handshake lines is controlled by the data source, while the remain-ing two lines are controlled by accepting devices. The three bus handshakelines are:

1. DAV (Data Valid)-The talker (source) controls the state of the DAV line.

2. NRFD (Not Ready For Data)-The listener (acceptor) controls the state ofthe NRFD line.

3. NDAC (Not Data Accepted)-The listener (acceptor) also controls theNDAC line.

The complete handshake sequence for one data byte is shown in Figure 2-2.Handshake can occur once data is high, indicating that all devices on the busare ready for data. At the same time NDAC should be low from the previousbyte transfer. If these conditions are not met, the source must then wait untilNRFD and NDAC lines have the correct status. Because of the possibility of abus hang up, some controllers have time-out routines to display error mes-sages, if the handshake sequence stops for any reason.

Once the NRFD and NDAC lines are properly set, the source sets the DAVline low, indicating that data on the bus is now valid. The NRFD line thengoes low and the NDAC line goes high once all devices on the bus haveaccepted the data. Each device releases the NDAC line at its own rate, but theNDAC line does not go high until the slowest device has accepted the data.

After the NDAC line goes high, the source then sets the DAV line high toindicate that the data on the bus is no longer valid. At this point, the NDACline returns to its low state. Finally, the NRFD line is released by each of thedevices at their own rates, until the NRFD line finally goes high when theslowest device is ready - and the bus is set to repeat the sequence with thenext byte of data.

The sequence described is used to transfer both data and multiline com-mands. The state of the ATN lines determines whether the data bus containsdata or commands (paragraph 2.4).


6

Figure 2-2. Handshake Sequence For One Data Byte

the bus are important, but the interface can transfer data correctly only withappropriate commands to control communications between the variousinstruments on the bus. This section briefly describes the purpose of the buscommands, which are grouped into the following three general categories:

1. Uniline commands: Sent by setting the associated bus line low.

2. Multiline commands: General bus commands sent when the ATN line islow.

3. Device-Dependent commands: Special commands that depend on deviceconfigurations; sent when ATN is high.

These commands are summarized in Table 2-1. (Only commands that affectModel 835 operation are covered in this section.)

2.4.1 Uniline Commands

Uniline commands are sent by setting the named command associated busline low. The ATN, IFC and REN commands are sent only by the systemcontroller. The SRQ command is generated and sent by an external device onthe bus. The EOI command may be sent by either the controller or an externaldevice. Following is a brief description of each command:

1. REN (Remote Enable)-When the controller sends the REN command, theinstrument is set up for remote operation before transfer of informationover the bus.

2. EOI (End Or Identity)-The EOI command is transmitted by setting the EOI

2.3.3 Data Lines

The IEEE-488 bus has eight data lines that allow data to be transmitted andreceived in a bit-parallel, byte-serial manner. These eight lines use the conven-tion D101 through D108 instead on the usual D0 through D7 binary terminol-ogy. The data lines are bidirectional, and like the bus management andhandshake signal lines, low is true.

Bus Commands

Hardware aspects of2.4


7

sequence.

3. IFC (Interface Clear)-The IFC command is sent by setting the IFC line low;it clears the bus interface.

4. ATN (Attention)-The controller sets the ATN line low when sendingmultiline commands. Device-dependent commands are sent with ATNhigh. (The ATN line must remain high while a device transmits its datastring.)

5. SRQ (Service Request)-The SRQ line is set low by an external device whenit requires service from the controller. A serial polling sequence (de-scribed in paragraph 3.4.7) must be used to determine which device hasrequested service.

2.4.2 Universal Commands (Multiline)

7

Table 2-1. IEEE-488 Bus Command Summary

Command State ofType Command ATN Line* Comments

Uniline REN (Remote Enable) X Set up for remote operation.EOI (End or Identify) X Sent by setting EOI low.IFC (Interface Clear) X Clears Interface.ATN (Attention) Low Defines data bus contents.SRQ (Service Request) X Controlled by external device

MultilineUniversal DCL (Device Clear) Low Returns device to default conditions.

LLO (Local Lockout) Low Disables most front panel controls.SPE (Serial Poll Enable) Low Enables serial polling.SPD (Serial Poll Disable) Low Disables serial polling.

Addressed SDC (Selective Device Clear) Low Returns unit to default conditionsGTL (Go to Local) Low Returns to local control.GET (Group Execute Trigger) Low Triggers device for reading.

Unaddressed UNL (Unlisten) Low Removes all listeners from bus.UNT (Untalk) Low Removes all talkers from bus.

Device-dependent** High Programs Model 835 for various modes.

* X = Don’t Care** For complete description refer to Section 3.


8

Universal commands are multiline commands that require no addressing. Allinstrumentation equipped to implement the command complies when thecommand is transmitted over the bus. (Like all multiline commands, theuniversal commands are sent with ATN low.)

1. DCL (Device Clear)-After DCL is sent, all instrumentation equipped toimplement the command reverts to some known state (all devices soequipped).

2. LLO (Local Lockout) - After LLO is sent, all instrumentation equipped toimplement the command will disable front panel controls. The Model 835disables all front panel controls except POWER, ZOOM and OFFSET.

3. SPE (Serial Poll Enable)-The SPE command is the first step in the serialpolling sequence (used to determine which instrument has requestedservice).

4. SPD (Serial Poll Disable)-The SPD comand is sent by the controller toremove all instrumentation on the bus from the serial poll mode. TheModel 835 then no longer places status bytes on the bus when addressed totalk (after the SPD command is sent).

2.4.3 Addressed Commands

Each of these commands must be preceded by a listen command coded for thedevice’s primary address, before the instrument will respond. Only theaddressed device responds to each of these commands:

1. SDC (Selective Device Clear)-The SDC command performs essentially thesame function as the DCL command (paragraph 2.4.2), except that onlythe addressed device responds.

2. GTL (Go to Local)-The GTL command changes instruments from theremote to local mode of operation.

3. GET (Group Execute Trigger)-The GET command triggers devices toperform some acton that depends on device configuration.

2.4.4 Unaddressed Commands

Two unaddressed commands from the controller remove all talkers andlisteners from the bus simultaneously. No addressing is required to imple-ment these commands.

1. UNL (Unlisten)-All listeners are removed from the bus at once when theUNL command is sent on the bus.

2. UNT (Untalk)-The controller sends the UNT command to remove anytalkers from the bus.

2.4.5 Device-Dependent Commands

The meaning of the device-dependent commands is determined by instru-ment configuraton. Generally, these commands are sent as one or more ASCIIcharacters and tell the device to perform a specific function. For completeinformation on using these commands with the Model 835, refer to Section 3.The IEEE-488 bus treats device-dependent commands as data since the ATNline is high when commands are transmitted.


9

Command Codes

Each bus command2.5 contains a unique code that is transmitted over the bus as 7 bit ASCII data.

This section briefly explains the code groups, which are summarized in Figure2-3. (Every command is sent with ATN low.)

1. Addressed Command Group (ACG)-Addressed commands are listed incolumn 0(B) in the table. Column 0(A) lists the corresponding ASCIIcodes.

2. Universal Command Group (UCG)-Columns 1(A) and 1(B) list the Univer-sal commands and the corresponding ASCII codes.

3. Listen Addressed Group (LAG)-Columns 2(A) and 3(A) list the ASCIIcodes corresponding to the primary address listed in columns 2(B) and3(B). For example, if the primary address of the instrument is set to eight,the LAG byte corresponds to the ASCII “(“ character.

4. Talk Address Group (TAG) - TAG primary address values and the corre-sponding ASCII characters are listed in columns 4(A) through 5(B).

The preceding address groups are all grouped together to form the PrimaryCommand Group (PCG). The bus also has another group of commands,called the Secondary Command Group (SCG). These are listed in Figure 2-3,at the end of this section, for informational purposes only. The Model 835does not respond to these commands, but other devices may have secondaryaddressing capability.

NoteCommands are normally transmitted with the 7 bit code listed in thetable. For most devices, the condition of D7(D108) is unimportant, asshown by the “Don’t Care” indication in the table. Some devices,however, may require that D7 is at a specific logic state before thecommands are recognized.

Hexadecimal and decimal values for each of the commands or commandgroups are listed in Table 2-2. Each value in the table assumes that D7 isset to 0.

Table 2-2. Hexadecimal and Decimal Command Codes

Command Hex Value* Decimal Value

GTL 01 1SDC 04 4GET 08 8

LLO 11 17DCL 14 20SPE 18 24

SPD 19 25LAG 20-3F 32-63TAG 40-5F 64-95

UNL 3F 63UNT 5F 95

*Values shown with D7 = 0


10


11

The correct command sequence must be sent by the controller before aninstrument will respond as intended. The universal commands, such as DCL,require only that ATN be set low before the command is sent. Other com-mands require that the device be addressed to listen first. This section brieflydescribes the bus sequence for several types of commands.

2.6.1 Addressed Command Sequence

Before a device responds to one of these commands, it must receive a LAGcommand containing its primary address. Table 2-3 shows a typical sequencefor the SDC command. (The example in the table assumes that the instrumenthas a factory set primary address of 22.)

NoteA UNL command is transmitted before the LAG SDC sequence.(This is generally done to remove all other listeners from the busfirst, so that only the addressed device responds.)

Table 2-3. Typical Addressed Command Sequence

Step Command ATN Data BusASCII Hex Decimal

1 UNL Set low ? 3F 63

2 LAG* Stays low 6 36 54

3 SDC Stays low EOT 04 4

4 Returns high

*Assumes primary address = 22.

2.6.2 Universal Command Sequence

Universal commands are sent by setting ATN low and then placing thecommand on the bus. For example, the following is placed on the bus to givethe DCL command:

ATN*DCL

NoteBoth the ATN and DCL commands are on the bus simultaneously.Also, addressing is not necessary.

2.6.3 Device-Dependent Command Sequence

Device-dependent commands are transmitted with ATN high. However, thedevice must be addressed to listen first - before the commands are transmit-ted. Table 2-4 shows the command sequence for the following:

D1X

This command, which sets up the Model 835 for the LOG function, is de-scribed in detail in Section 3.

Figure 2-3. Command Codes

2.6Command Sequence


12

Table 2-4. Typical Device-Dependent Command Sequence

Step Command ATN Data BusASCII Hex Decimal

1 UNL Set low ? 3F 63

2 LAG* Stays low 6 36 54

3 Data Set high D 44 68

4 Data Stays high 1 31 49

5 Data Stays high X 58 88

*Assumes primary address = 22.


13

Introduction3.1

Before the Model 835 can be used with the IEEE-488 bus, the instrument mustbe connected to the bus using a suitable connector. Also, the instrument mustbe set up for addressable operation and the primary address must be properlyselected as described in this section.

NoteAllow the Model 835 (with installed 835-IEEE interface) to warm up(power on) for one hour before using in order to stablize analogcircuitry.

HardwareConsiderations3.2

3.2.1 Typical Controlled Systems

The IEEE-488 bus is a parallel interface in a data transfer and control system.As a result, adding more devices is simply a matter of using more cables tomake the desired connections. Because of this flexibility, system complexitycan range from a very simple to an extremely complex system.

Figure 3-1 shows two typical system configurations. Figure 3-1(a) shows thesimplest possible controlled system. The controller is used to send commandsto the instrument, which sends data back to the controller.

The system becomes more complex in Figure 3-1(b), where additional instru-mentation is added. Depending on programming, all data may be routedthrough the controller, or it may be transmitted directly from one instrumentto another.

For very complex applications, a larger computer can be used. Tape drives ordisks can then be used to store data.

Section 3

Operation

The Model 835-IEEE Interface is designed to interface the Model 835 to theIEEE-488 bus. The current, and therefore power, ranges, zero check, loga-rithm, (dBm/dB), attenuator, ratio/referene, wavelength, and null featuresare controlled by programming commands over the IEEE-488 bus. In addi-tion, interface characteristics such as End or Identify (EOI), Status RequestConditions (SRQ), Output Format, and Data Terminator can be programmed.Data sent by the interface includes power, power range, wavelength, detectorand attenuator serial numbers, status byte, and status word.This section dealswith important hardware and software aspects of bus operation, and de-scribes important programming functions in detail. Included are: general buscommands, device-dependent commands, status word and status byte, andother important operating information.


14

Figure 3-1. Typical Controlled Systems

3.2.2 Bus Connections

The Model 835 is connected to the bus through an IEEE-488 connector, shownin Figure 3-2. This connector is designed to be stacked to allow a number ofparallel connections on one instrument.

NoteTo avoid possible mechanical damage, it is recommended that no morethan three connectors be stacked on any one connector on an instru-ment. Otherwise, resulting strain may cause internal damage.

Figure 3-2. IEEE-488 Connector

A typical connecting arrangement for the bus is shown in Figure 3-3. Eachcable normally has the standard IEEE connector on each end. Once theconnections are made, the screws are to be tightened securely. (The connectoris located on the rear panel of the Model 835.)


15

NoteThe IEEE-488 bus is limited to a maximum of 15 devices, including thecontroller. Also, the maximum cable length is 20 meters. Failure tocomply with these limits will probably result in erratic bus operation.

Custom cables may be constructed using the information in Table 3-1 andFigure 3-4. Table 3-1 lists the contact assigments for the various bus lines, andFigure 3-4 shows contact designations. Contact 18 through 24 are return lines

for the indicated signal lines, and the cable shield is connected to contact 12.Each ground line is connected to digital common in the Model 835.

Figure 3-4. Contact Assignments

Caution

Voltage between IEEE common and ground must not exceed 30V, ordamage to the instrument may occur.

A typical signal line bus driver is shown in Figure 3-5. With the configurationshown, the driver has bidirectional capability. When the I/O control line ishigh, the driver functions as an output bus driver for the line. When thecontrol line is low, the driver is set up for line input operation.


16

Table 3-1. IEEE Contact Designations

Contact IEEE-488Number Designation Type

1 D101 Data2 D102 Data3 D103 Data

4 D104 Data5 EOl (24)* Management6 DAV Handshake

7 NRFD Handshake8 NDAC Handshake9 IFC Management

10 SRQ Management11 ATN Management12 SHIELD Ground

13 D105 Data14 D106 Data15 D107 Data

16 D108 Data17 REN (24)* Management18 Gnd, (6)* Ground

19 Gnd, (7)* Ground20 Gnd, (8)* Ground21 Gnd, (9)* Ground

22 Gnd, (10)* Ground23 Gnd, (11)* Ground24 Gnd, LOGIC Ground

*Numbers in parentheses refer to signal ground return of referencecontact number EO1 and REN signal lines return on contact 24.


17

NoteNot all signal lines use the bidirectional capability. Some lines, such asATN, will always function as output lines from the controller and asinput lines for all other devices on the bus.

Figure 3-5. Typical IEEE-488 Bus Driver (One of 16)

3.2.3 Addressable Mode Selection

The Model 835 must be set to the addressable mode when used with anexternal controller. Mode selection is done with the TO/ADDRESSABLEmode selection switch located on the rear panel of the Model 835. This switchis grouped with the five switches that set the primary address; these switchesare located on the rear panel of the Model 835. Figure 3-6 shows the switch(6) set at the ADDRESSABLE position.

The TO/ADDRESSABLE switch mode is read only at power-up. If the modeis changed, the Model 835 must first be turned off, then powered-up again(cycle instrument power), before it will respond to the new switch position.

Figure 3-6. TO/ADDRESSABLE and Primary AddressSwitches (Factory Set Address 22 Shown)

3.2.4 Primary Address Selection

The Model 835 must receive a listen command before it responds to theaddressed, or device-dependent commands, sent over the bus. Similarly, atalk command must be sent to the Model 835 before it will transmit its datastring, status word, or status byte. These talk and listen commands are sentwith the primary address of the instrument. The primary address of theModel 835 interface is set to 22 at the factory, but it may be set to any valuebetween 0 and 30 by placing the primary address switches (1-5, Figure 3-6) tothe required positions. The primary address, used for the Model 835 in thecontroller’s programming language must be identical to the primary addressset on the Model 835.

Note


18

The primary address switches set address is read only at power-up. Ifthe address is changed, the Model 835 must be first turned off, and thenpowered-up again (cycle power) before the new address can be used.

Correct switch positions for the factory set address of 22 is shown in Figure 3-6. (If a different address is required, the primary address may be changed asindicated in Table 3-2.

NoteIf other instrumentation is also connected to the bus, be sure that eachdevice has a different primary address. Not complying with thisprecaution may result in erratic bus operation.

The primary address switches are binary weighted; A1 is the least significantbit, and A5 is the most significant bit. (For example, the binary value for aprimary address of eight is 01000. Use the tip of a pen or pencil to operate theswitches.)

NoteNo instrument on the bus (including the Model 835) should be oper-ated with a primary address of 31, although it is possible to set theswitches to those positions (11111). This address is reserved for theUNL and UNT commands. (If primary address 31 is used, instrumentswill respond by removing themselves from the talk or listen modes.)

3.3 computer in the world is useless without the necessary software. This basicrequirement is also true of the IEEE-488 bus, which requires the use of han-dler routines described in this section.

3.3.1 Controller Interface Routines

Before a controller can be used with the IEEE-488 interface, the user mustmake certain that appropriate handler software is present in the controller.(For example, with the HP-85 computer, the HP-85 interface card must beused with an additional I/O ROM - which contains the necessary handlersoftware.)

Other small computers that can be used as controllers have limited IEEEcommand capability. PET/CBM computers, for example, are incapable ofsending the universal and addressed multiline commands from BASIC,although most of these commands may be sent through machine-languageroutines. Capabilities of other small computers depend on the particularinterface used. (Often, little software “tricks” are required to achieve thedesired results.)

It is very important to make sure the proper software is being used with theinterface. Often, the user may incorrectly suspect that a hardware problem iscausing an intermittent fault, when in fact, software is the problem.

Software Assembly

The most sophisticated


19

3.3.2 HP-85 BASIC Statements

Many of the programming instructions use examples written in Hewlett-Packard Model 85 BASIC. The HP-85 was chosen for these examples becauseit has a large number of BASIC statements that control IEEE-488 operation.This section covers those HP-85 BASIC statements that are essential to Model835 operation.

A complete list of HP-85 IEEE-488 BASIC statements is in Table 3-3. All thestatements in the table have a one or three digit interface select code, which isset to 7 at the factory. The last two digits, of those statements that requirethree digits, specify the primary address. Generally, only those commandsthat actually require an address to be sent over the bus need to specify theprimary address.

The statements in the table with three digits assume that the primary address

Table 3-2. Primary Address Switch Positions

PrimaryAddress 5 4 3 2 1

0 0 0 0 0 01 0 0 0 0 12 0 0 0 1 0

3 0 0 0 1 14 0 0 1 0 05 0 0 1 0 1

6 0 0 1 1 07 0 0 1 1 18 0 1 0 0 0

9 0 1 0 0 110 0 1 0 1 011 0 1 0 1 1

12 0 1 1 0 013 0 1 1 0 114 0 1 1 1 0

15 0 1 1 1 116 1 0 0 0 017 1 0 0 0 1

18 1 0 0 1 019 1 0 0 1 120 1 0 1 0 0

21 1 0 1 0 122 1 0 1 1 023 1 0 1 1 1

24 1 1 0 0 025 1 1 0 0 126 1 1 0 1 0

27 1 1 0 1 128 1 1 1 0 029 1 1 1 0 130 1 1 1 1 0


20

Table 3-3. HP-85 IEEE-488 BASIC Statements

Statement Action Bus Command Sequence

ABORTIO 7 Send IFC IFCCLEAR 7 Send DCL ATN*DCLCLEAR 722 Send SDC to device 22. ATN*UNL;MTA;LAG;SDC

ENTER 722;A$ Device 22 addressed to talk. ATN*UNL;MLA;TAG;ATN ;dataData placed in A$.

LOCAL 722 Send GTL to device 22. ATN*UNL;MTA;LAG;GTLLOCAL LOCKOUT 7 Send LLO ATN*LLO

OUTPUT 722;A$ Device 22 addressed to listen. ATN*MTA;UNL;LAG;ATN ;dataTransmit A$.

REMOTE 7 Set REN true. RENREMOTE 722 Send REN true. REN;ATN*UNL;MTA;LAG

Address device 22 to listen

RESET 7 Send IFC, cancel REN. IFC;REN;RENSPOLL(722) Address device 22 to talk. ATN*UNL;MLA;TAG;SPE;

Conduct serial poll. ATN ; status byte;ATN*SPD;UNT

TRIGGER 7 Send GET ATN*GETTRIGGER 722 Address device 22 to listen. ATN*UNL;MTA;LAG;GET

Send GET.

of the device (in this case the Model 835) is set at 22. Other primary addressesrequire that the last two digits be set to the corresponding value. (For ex-ample, to send a GTL command to device 21, the following BASIC statementis used: LOCAL 721.)

Some of the statements in the table have two forms; the exact configurationused depends on the desired command. (For example, CLEAR 7 causes aDCL to be sent, while CLEAR 722 causes an SDC to be transmitted to device22.)

The third column of Table 3-3 lists the mnemonics for the command se-quences. While most of these have been covered before, the following infor-mation should be noted. As described earlier, the ATN line is set low by thecontroller if the data bus contains a multiline command. This is indicated inthe table by ANDing the ATN mnemonics with the first command on the bus.(For example, ATN*GET sends ATN and GET simultaneously.)

Two commands not previously covered are MLA (My Listen Address) andMTA (My Talk Address). These are ordinary PCG (Primary CommandGroup) addresses sent by the HP-85 for bus operation in some situations. TheModel 835 normally ignores these commands, but other devices may requirethat MLA and MTA be present in the command sequence - under certaincircumstances.

NoteThe HP-85 address is set to 21 at the factory. Since each device on thebus must have a unique primary address, do not set the Model 835 tothis address to avoid conflict with the HP-85.

3.3.3 Interface Function Codes


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The interface function codes are specified in the IEEE-488 (1978 Standards).These codes define an instrument’s ability to support various interfacefunctions, and are not to be confused with programming commands foundelsewhere in this manual.

The codes for the Model 835 are listed in Table 3-4. These codes are also onthe rear panel of the instrument for convenience, above the IEEE connector.

Table 3-4. Model 835 Interface Function Codes

Code Interface Function

SH1 Source Handshake CapabilityAH1 Acceptor Handshake CapabilityT5 Talker (Basic Talker, Serial Poll, Talk Only Mode,

Unaddressed To Talk On LAG)L4 Listener (Basic Listener, Unaddressed To Listen on TAG)SR1 Service Request CapabilityRL1 Local Lockout/Remote CapabilityPP0 No Parallel Poll CapabilityDC1 Device Clear CapabilityDT1 Device Trigger CapabilityC0 No Controller CapabilityE1 Open Collector Bus DriversTE0 No Extended Talker CapabilitiesLE0 No Extended Listener Capabilities

The numeric value following each one or two letter code defines Model 835capabilities/functions as follows:

1. SH1 (Source Handshake Function) - The ability to initiate the transferof message/data on the data bus.

2. AH1 (Acceptor Handshake Function) - The ability to ensure properreception of message/data on the data bus.

3. T5 (Talker Function) - The ability to send device-dependent data overthe bus (to other devices). (Talker capabilities exist only after theinstrument has been addressed to talk.)

4. L4 (Listener Function) - The ability to receive device-dependent dataover the bus from other devices. (Listener function capabilities existonly after it is addressed to listen.)

5. SR1 (Service Request Function) - The ability to request service fromthe controller.

6. RL1 (Remote-Local Function) - The ability to be in remote or localmodes of operation. Local Lockout capability.

7. PP0 (Parallel Poll Function) - The Model 835 has no parallel pollingcapabilities.

8. DC1 (Device Clear Function) - The ability for Model 835 to be cleared(initalized).

9. DT1 (Device Trigger Function) - The ability to have its readingstriggered.


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Table 3-5. IEEE Command Groups

HANDSHAKE COMMAND GROUPDAC = DATA ACCEPTEDRFD = READY FOR DATADAV = DATA VALID

UNIVERSAL COMMAND GROUPATN = ATTENTIONDCL = DEVICE CLEARIFC = INTERFACE CLEARLLO = LOCAL LOCKOUTREN = REMOTE ENABLESPD = SERIAL POLL DISABLESPE = SERIAL POLL ENABLE

ADDRESS COMMAND GROUPLISTEN: LAG = LISTEN ADDRESS GROUP

MLA = MY LISTEN ADDRESSUNL = UNLISTEN

TALK: TAG = TALK ADDRESS GROUPMTA = MY TALK ADDRESSUNT = UNTALKOTA = OTHER TALK ADDRESS

ADRESSED COMMAND GROUPACG = ADDRESSED COMMAND GROUPGET = GROUP EXECUTE TRIGGERGTL = GO TO LOCALSDC = SELECTIVE DEVICE CLEAR

STATUS COMMAND GROUPRQS = REQUEST SERVICESRQ = SERIAL POLL REQUESTSTB = STATUS BYTEEOI = END

10. C0 (Controller Function) - The Model 835 has no controller capabilities.

11. TE0 (Extended Talker Capabilities) - The Model 835 has no extendedtalker capabilities.

12. LE0 (Extended Listener Capabilities) - The Model 835 has no extendedlistener capabilities.

3.3.4 Model 835 Interface Commands

Interface commands controlling Model 835 operation are listed in Table 3-5.(Not included in the table are device-dependent commands, which arecovered in detail in paragraph 3.5.)


23

those commands with the same general meaning regardless of instrumentconfiguration. These commands are grouped into two categories:

1. Addressed Commands: These commands require that the primaryaddress of the instrument be identical to the primary address in thecontroller’s programming language.

2. Unaddressed Commands: No primary address is required for thesecommands. All devices with capabilities and set up to implementthese commands will do so simultaneously when the command is sent.

General bus commands are summarized in Table 3-6, which also lists the HP-85 BASIC statement that sends each command. (Each addressed commandstatement assumes a primary address of 22.)

NoteThe Model 835 must be set for a primary address of 22 to work withaddressed command examples.

3.4.1 REN (Remote Enable)

The remote enable command is sent to the Model 835 by the controller to set itup for remote operation. Generally, this should be done before attempting toprogram the instrument over the bus. The Model 835 indicates that it is in theremote mode by displaying the RMT annunciator.

To set up the Model 835 in the remote mode, the following steps must beperformed at the controller:

1. Set the REN line low.

2. Address and command the Model 835 to listen.

NoteSetting REN true without addressing does not cause the RMT annun-ciator to turn on; however, once REN is true, the RMT annunciatorturns on the next time an addressed command is received.

Programming Example - This sequence is automatically sent by the HP-85,

General BusCommandProgramming

General bus commands are

3.4

Table 3-6. General Bus Commands

Addressing HP-85 BASICCommand Required ? Statement

REN Yes REMOTE 722IFC No ABORTIO 7GTL Yes LOCAL 722

DCL No CLEAR 7LLO No LOCAL LOCKOUT 7SDC Yes CLEAR 722

GET* Yes TRIGGER 722GET* No TRIGGER 7

*GET - sent with or without addressing.


24

when the following is typed into the keyboard:

REMOTE 722 (END LINE)

After the END LINE key is pressed, the Model 835 RMT annunciator comeson. (If not, check to see that the instrument is set for the proper primaryaddress. Also, check to see that all bus connections are secure.)

3.4.2 IFC (Interface Clear)

The IFC command is sent by the controller to set the Model 835 to the talk andlisten idle states.

To send the IFC command, the controller need only set the IFC line true.

Programming Example - Before demonstrating the IFC command, turn on theRMT annunciator if it is not already on, by entering the following statementsinto the HP-85 computer:

REMOTE 722 (End Line)

The RMT annunciator is now on. The IFC command may now be sent byentering the following statement into the HP-85:

ABORTIO 7 (End Line)

After the END LINE key is pressed, the Model 835 is in the talk idle state.

3.4.3 GTL (Go To Local)

The GTL command takes the instrument out of the remote mode. To send theGTL command, the following sequence must be performed at the controller:

1. Set ATN true.

2. Address the Model 835 to listen.

3. Place the GTL command on the bus.

Programming Example - If the instrument is not in the remote mode, enter thefollowing statement into the HP-85:


Check to see that the RMT annunciator is on. The GTL command sequence isautomatically sent by the HP-85 with the following statement:

LOCAL 722 (End Line)

The RMT annunciator then turns off.

NoteSetting REN false with the LOCAL 7 statement also takes the instru-ment out of the remote mode.

3.4.4 DCL (Device Clear)

The DCL command may be used to clear the Model 835, setting it to a knownstate. All devices on the bus equipped to respond to a DCL do so simultane-ously. (When the Model 835 receives a DCL command, it returns to thedefault conditions in Table 3-7.

To send the DCL command, the following steps must be performed on the


25

Table 3-7. Default Conditions

(Status Upon Power Up or After SDC or DCL)

Mode Value Status

Attenuator — Reflects saved status in NVRAM.Wavelength — Reflects saved value in NVRAM.Log (dBm/dB) D0 Off

Ratio/Ref F0 OffCalibration — OffZero Check C0 Off

Range R0 AutorangeRelative Z0 OffEOI K0 Send EOI.

Trigger T0 Continuous on Talk.SRQ M00 DisabledData Format G0 Send prefix.Terminator Y(CR LF) CR LF

controller :

1. Set ATN true.

2. Set the DCL command on the bus.

Programming Example - Using front panel controls, select the 2µW range.Also enable the REL and LOG modes. Now enter the following statement intothe HP-85:

CLEAR 7 (End Line)

After the END LINE key is pressed, the instrument returns to power-up status.

y is pressed, the instrument returns to power-up status.

3.4.5 SDC (Selective Device Clear)

The SDC command performs the same function as the DCL command, exceptthat only the addressed device responds. This command is useful for clearingonly selected instruments instead of all instruments simultaneously. TheModel 835 returns to the default conditions listed in Table 3-7 when respond-ing to an SDC command.

To transmit the SDC command, the following steps must be performed on thecontroller :

1. Set ATN true.


3. Set the SDC command on the data bus.

Programming Example - Using front panel controls, select the 2µW range andenable the REL mode. Enter the following statement into the HP-85:

CLEAR 712 (End Line)

Note that the instrument does not respond because the SDC command was


26

sent with a primary address of 12. Then enter the following statement intothe HP-85 keyboard:

CLEAR 722 (End Line)

The instrument returns to the default conditions listed in Table 3-7.

3.4.6 GET (Group Execute Trigger)

The GET command is sent to the Model 835 to trigger the instrument. TheGET command is only one of several methods that can be used to triggerreadings. (More detailed information on all trigger modes, including GET isin paragraph 3.5.8.

To send the GET command over the bus, the following sequence must beperformed on the controller:

1. Set ATN true.


3. Place the GET command on the data.

GET can also be sent, without addressing, by omitting step 2.

Programming Example - Type in the following statement in the HP-85 key-board:


Set the instrument in the one-shot on GET trigger mode with the followingstatement:

OUTPUT 722; “T3X” (End Line)

After the END LINE key is pressed, the instrument waits for a trigger.

The instrument may be triggered to take a single reading, with the followingstatement:

TRIGGER 722 (End Line)

After END LINE is pressed one reading is processed.

NoteModel 835 also responds to GET without addressing. This commandis sent with the following HP-85 statement:

TRIGGER 7

The preceding examples use device-dependent commands to select instru-ment trigger modes. These commands are covered in detail in paragraph 3.5.

3.4.7 LLO (Local Lockout)

The Local Lockout Command is used to remove the instrument from localoperating mode. After the unit executes LLO, all its front panel controlsexcept POWER and those buttons which control the bar graph display will beinoperative. REN must be true for the instrument to respond to LLO. RENmust be set false to cancel LLO.

To send the LLO command, the controller must perform the following steps:

1. Set ATN true.

2. Place the LLO command on the data bus


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Programming Example — The LLO command is sent by using the HP-85statements:

REMOTE 7 (End Line)LOCAL LOCKOUT 7 (End Line)

After the second statement is entered, the instrument’s front panel controls,with the exception of POWER, ZOOM <|, |>, and OFFSET will be lockedout.

To re-enable local operation, use the following statements:

LOCAL 7 (End Line)REMOTE 722 (End Line)

3.4.8 SPE, SPD (Serial Polling)

The serial polling sequence requests and obtains the Model 835 status byte.Usually, the serial polling sequence is used to determine which of severaldevices has requested service over the SRQ line. (However, the serial pollingsequence may be used at any time to obtain the status byte format, refer toparagraph 3.5.10.)

The serial polling sequence is conducted as follows:

1. The controller sets the ATN line true.

2. The SPE (Serial Poll Enable) command is sent on the bus by the con-troller.

3. The Model 835 is addressed to talk.

4. The controller sets ATN false.

5. The instrument then sets its status byte on the bus which is read by thecontroller.

6. The controller then sets the ATN line low and sends SPD (Serial PollDisable) on the bus to end the serial polling sequence.

Steps 3 through 5 may be repeated for other instruments on the bus, by usingthe correct talk address for each instrument. (ATN must be true when the talkaddress is transmitted, and false when the status byte is read.)

Programming Example — The HP-85 SPOLL statement automatically per-forms the serial polling sequence. To demonstrate serial polling, momentarilypower down the Model 835 and enter the following statements into the HP-85keyboard.

REMOTE 722 (End Line)S = SPOLL (722) (End Line)

DISP S (End Line)

After END LINE is pressed the second time, the computer performs the serialpolling sequence. After the END LINE is pressed the last time, the status bytevalue is displayed on the CRT. (Paragraph 3.5.10 covers the status byteformat in detail.)


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Device-DependentCommandProgramming

IEEE device-dependent

3.5 commands are sent to the Model 835 to control various operating modes suchas attenuator, Log (dBm/dB), ratio/reference, relative, range, wavelength anddata format. Each command is made up of an ASCII alpha character followedby one or more numbers designating specific parameters. For example, Log(dBm/dB) is programmed by sending an ASCII “D” followed by a zero or one(for turning it off or on). (The IEEE bus treats device-dependent commands asdata since ATN is high when the commands are transmitted.)

A number of commands may be grouped together in one string. A commandstring is terminated by an ASCII “X” character, which tells the instrument toexecute the command string.

If an illegal command or command parameter is present within a commandstring, the instrument will:

1. Ignore the entire command string.

2. Set appropriate error bits in the status byte.

3. Generate an SRQ if programmed to do so.

These programming aspects are covered in paragraph 3.5.10.

HP-85 examples are included throughout this section to clarify programming.

NoteBefore performing a programming example, it is recommended thatthe instrument be set to its default values by sending an SDC over thebus. (For information on using the SDC command, refer to paragraph3.4.5.)

If the HP-85 “hangs up” at any point, operation may be restored by holdingthe SHIFT key down and then pressing RESET on the keyboard.

In order to send a device-dependent command, the following sequence mustbe performed on the controller:

1. Set ATN true.


3. Set ATN false.

4. Send the command string over the data bus, one byte at a time.

Programming Example — Device-dependent commands are sent by the HP-85 using the following statement:

OUTPUT 722;A$ (End Line)

A$ in this case contains the ASCII characters that form the command string.

NoteREN must be true when attempting to program the Model 835. If RENis false, the RMT annunciator is off.

Commands that affect the Model 835 are listed in Table 3-8. (All commandslisted in Table 3-8 are covered in detail in following paragraphs.)

NoteProgramming Examples that follow assume that the Model 835 pri-mary address is 22 (factory setting).

3.5.1 Execute (X)


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Table 3-8. Device-Dependent Command Summary

Mode Command Description

Attenuator A0 Attenuator OffA1 Attentuator On

Zero Check C0 Zero check OffC1 Zero check On

LOG (dBm/dB) D0 LOG (dBm/dB) OffD1 LOG (dBm/dB) On

Ratio/Reference F0 Ratio/Reference OffF1 Ratio/Reference On

Range Sending Current Reading PowerR0 Auto AutoR1 2 nA 2 nWR2 20 nA 20 nWR3 200 nA 200 nWR4 2 µA 2 µWR5 20 µA 20 µWR6 200 µA 200 µWR7 2 mA 2 mWR8 — 20 mWR9 — 200 mW

R10 — 2 WR11 — 20 W

Null (Rel) Z0 Null offZ1 Null on

Trigger T0 Continuous on talk.T1 One-shot on talk.T2 Continuous on GET.T3 One-shot on GET.T4 Continuous on X.T5 One-shot on X.

EOI K0 EOI enabled.(Transmit on last byte out.)

K1 EOI disabled.

Status Word U0 Output status word.

Wavelength U1 Output wavelength string

SRQ Mode Mnn SRQ on error and/or data conditions.

Data Format G0 Readings with prefix.G1 Readings without prefix.

Digital Calibration V± n.nnnn E±nn n represents calibration value.

Store L0 Store current calibration constantsand exit calibration.

Terminator Y(ASCII) ASCII character.Y(LF) CR LFY(CR) LF CR

Y(DEL) None

Execute X Execute other device-dependentcommands.


30

The execute command is implemented by sending an ASCII “X” on the bus. Ittells the Model 835 to execute other device-dependent commands. Generally,the “X” character is the last byte in the command string. The execute charac-ter also controls instrument operation in the T4 and T5 trigger modes (para-graph 3.5.8).

NoteCommand strings sent without an execute character are not executedat that time; they are stored in command buffer. The next time anexecute character is received, the stored commands are executed, if allprevious string commands were valid.

Programming Example — Enter the following statement sequence in the HP-85 keyboard:

REMOTE 722 (End Line)OUTPUT 722; “X” (End Line)

After the END LINE key is pressed the second time, the instrument receivesthe command. (No changes occur for this example because no other com-mands were given.)

3.5.2 Zero Check (C)

Zero check is controlled by sending one of the following commands on thebus:

C0 = Zero Check OffC1 = Zero Check On

Once zero check is enabled (C1 sent), the display can be zeroed using the RELfeature, or the front panel zero pot.

At power-up, or after the instrument receives a DCL or SDC command, the C0mode is enabled.

Programming Example - Enter the following statements into the HP-85Keyboard:

REMOTE 722 (End Line)OUTPUT 722; “C1X” (End Line)

After the END LINE key is pressed the second time, zero check is enabled andindicated by the ZERO CHECK annunciator.

3.5.3 Log - dBm/dB (D)

The Log function is controlled by sending one of the following commandsover the bus:

D0 = Log (dBm/dB) OFFD1 = Log (dBm/dB) ON

At power-up, or after the instrument receives a DCL or SDC command, theD0 mode is enabled.


31

Programming Example - Enter the following statements into the HP-85keyboard:

REMOTE 722 (End Line)OUTPUT 722; “D1X”(End Line)

After the END LINE key is pressed the second time, the LOG (dBm/dB)function is enabled and indicated by the LOG annunicator.

3.5.4 Attenuator (A)

The attenuator function is controlled by sending one of the following com-mands over the bus :

A0 = Attenuator OffA1 = Attenuator On

At power-up, or after the instrument receives a DCL or SDC command, theA0 mode is enabled.

Programming Example - Cycle power on the Model 835 and manually selectthe attenuator mode. Enter the following statements into the HP-85:

REMOTE 722 (End Line)OUTPUT 722; “A1X” (End Line)

After the END LINE key is pressed the second time, attenuator function isenabled and indicated by the attenuator annunciator.

3.5.5 Ratio/Reference (F)

The Ratio/Reference function is controlled by sending one of the followingcommands over the bus:

F0 = Ratio/Reference Mode OffF1 = Ratio/Reference Mode On

At power-up, or after the instrument receives a DCL or SDC command, the F0mode is enabled.

Programming Example - Cycle power on the Model 835 and manually selectthe ratio/reference mode. Enter the following statements into the HP-85:

REMOTE 722 (End Line)OUTPUT 722; “FIX” (End Line)

After the END LINE key is pressed the second time, the ratio/referencefunction is enabled and indicated by the power an

3.5.6 Range (R)

Selection of the current ranges or autoranging are programmable using thebus. The full scale power range for any particular current range depends onthe detector response, and is therefore wavelength dependent. The rangecommands are in Table 3-8.

After power-up, or after receiving a DCL or SDC, the range of the Model 835changes its range to autoranging.

Programming Example - Cycle power on the Model 835 and manually select


32

the 2mW range. Enter the following statements into the HP-85:

REMOTE 722(End Line)OUTPUT 722; “R5X” (End Line)

After END LINE is pressed the second time, the instrument switches to the R5current range (20 µA).

NoteThe range set over the IEEE bus is the current range, not the powerrange. The power range for a given current range is determined by thedetector response. For most detectors without attenuators, the currentrange is the same as the power range. However, when using attenua-tors, they may be three (3) or more orders of magnitude different. Thedifference is wavelength dependent.

To determine the power and current range correspondence, set range R7(2mA), and read the status word (paragraph 3.5.15). Read bits 8 and 9 todetermine the power range. The difference between the current range set andthe power range read is the same for all ranges at a particular wavelength.For example, is the range R7 is set by executing and R7X command, and therange indicated in bits 8 and 9 of the status word contain 09, the 2 mA currenttrange corresponds to a 200 mW power range. Similarly, the 200 µA currentrange (R6) corresponds to the 20 mW power range (08). Note that the differ-ence may be wavelength dependent.

3.5.7 Null (REL) (Z)

The Null (REL) modes is used for baseline suppression, as described inparagraph 2.7.7 of the Model 835 Operating Manual (Newport Part # 13767-01). When a correct Null On (Z1) command is executed, the input current isstored. The stored current is subtracted from subsequent readings, and thedifference between the input and stored current is used to compute the opticalpower.

When Null Off (Z0) is executed, the stored current is cleared.

The Null mode is controlled by sending one of the following commands overthe bus:

Z0 = Null OffZ1 = Null On

After power-up, or after DCL or SDC, Z0 is selected.

Programming Example - With the front panel Null button, turn Null off, andenter the following statements into the HP-85 keyboard:

REMOTE 722 (End Line)OUTPUT 722;”Z1X” (End Line)

After the END LINE key is pressed the second time, the REL annunciatorturns on.

3.5.8 Triggering (T)

Triggering starts a reading conversion with the instrument. The Model 835may be triggered in two basic ways: in a continuous mode, a single triggercommand starts a continuous series of readings. In a one-shot trigger mode, aseparate trigger is required to start each conversion.

The Model 835 has six trigger commands as follows:


33

T0 Continuous On TalkT1 One-Shot On TalkT2 Continuous On GETT3 One-Shot On GETT4 Continuous On XT5 One-Shot On X

After power-up, or after a DCL or SDC command, the T0 mode is enabled.

In the T0 and T1 modes, triggering occurs by addressing the Model 835 totalk, In the T2 and T3 modes, a GET command provides the trigger. In theT4 and T5 modes, the execute (X) character triggers the instrument.

Programming Example - Select the one-shot on talk mode with the followingHP-85 statement sequence:

REMOTE 722 (End Line)OUTPUT 722;”T1X” (End Line)

After the END LINE key is pressed the second time, the instrument is in theone-shot on talk trigger mode. The instrument is waiting for a trigger.

Trigger the instrument, with a talk command, by entering the followingstatement into the HP-85:

ENTER 722;A$ (End Line)

After pressing END LINE one reading is processed. To continue takingreadings in this mode, one talk command must be sent for each conversion.

3.5.9 EOI (K)

The EOI line on the bus is usually set low by a device during the last byte ofits data transfer sequence. This properly identifies the last byte, allowingvariable length data words to be transmitted. The Model 835 normally sendsEOI during the last byte of its data string or status word. The EOI response ofthe instrument is sent with one of the following commands:

KO sends EOI during last byte.K1 sends no EOI.At power-up, the KO mode is enabled.

Programming Example-Model 835 EOI response is suppressed with thefollowing HP-85 statement sequence:

REMOTE 722 (END LINE)OUTPUT 722;”K1X” (END LINE)

NoteThe HP-85 does not normally rely on EOI to mark the last byte of datatransfer. Some controllers, however, may require that EOI be presentat the end of transmitting.

3.5.10 SRQ Mode (M) and Status Byte Format

The SRQ command controls which of a number of conditions within theModel 835 that cause the instrument to request service from the controller bygenerating an SRQ command. Once an SRQ is generated, the Model 835status byte can be checked to determine if it was the Model 835 that requestedservice. (Other bits in the status byte may also be set depending on certain


34

data or error conditions.)

The Model 835 can be programmed to generate an SRQ, if one or more of thefollowing conditions exist:

1. A reading has been completed.2. An overflow condition occurs.3. A busy condition occurs.4. An Illegal Device-Dependent Command Option (IDDCO) is received.5. An Illegal Device-Dependent command (IDDC) is received.6. The instrument is not in remote when a command is sent.

After power-up, or after a DCL or SDC command, SRQ is disabled.

SRQ MASK-To facilitate SRQ programming, the Model 835 uses an internalmask to generate an SRQ. When a particular mask bit is set, the Model 835sends an SRQ when those conditions occur. Bits within the mask are con-trolled by sending the ASCII letter “M”, followed by a decimal number to setthe appropriate bits. The commands to set the various mask bits are listed inTable 3-9.

Table 3-9. SRQ Mask Commands

Command Status Bits Set Conditions to Generate SRQ

M0 None Clears SRQ Data MaskM1 B0 Reading OverflowM8 B3 Reading Done

M9 B3, B0 Reading Done or Reading OverflowM16 B4 BusyM17 B4, B0 Busy or Reading Overflow

M24 B4, B3 Busy or Reading DoneM25 B4, B3, B0 Busy, Reading Done or Reading

Overflow

M32 None Clears SRQ Error MaskM33 B5, B0 IDDCOM34 B5, B1 IDDC

M35 B5, B1, B0 IDDC or IDDCOM36 B5, B2 Not in RemoteM37 B5, B2, B0 Not in Remote or IDDCO

M38 B5, B2, B1 Not in Remote or IDDCM39 B5, B2, B1, B0 Not in Remote, IDDC or IDDCO

Programming Example - Cycle power on the Model 835, program it for SRQon IDDCO, and output the status word.

Program Comments

10 REMOTE 722 Set up for remote operation.20 OUTPUT 722; “M33X” Program for SRQ on IDDCO.30 OUTPUT 722; “U0X” Send status command. Section 3.5.1540 ENTER 722; A$ Enter commands into computer.50 DISP A$ Display on CRT60 END


35

After entering the program, press the HP-85 run key. The U0 status word isdisplayed. The Me bytes (Figure 3-9) contain “01”, indicating Model 835 isnow programmed to SRQ on an IDDCO.

Status Byte Format-The status byte contains information relating to data anderror conditions within the instrument. When a particular bit is set, certainconditions are present. The meanings of the various bits are listed in Table 3-10. Figure 3-7 shows the general format of the status byte, which is obtainedby using the SPE and SPD polling sequence described in paragraph 3.4.8.

If the status byte is read when no SRQ was generated by the Model 835 (bit 6is clear), the current status of the instrument is read. (For example, if areading is done, bit 3 is set.)

When an SRQ is generated by the Model 835, bit 6 of the status byte is set. Ifthe SRQ was caused by an error condition, bit 5 is also set along with one ofthe error condition bits (B0, B1 or B2). (Only the error that causes the initialSRQ will be defined by the status byte.)

If the SRQ was caused by a data condition, bit 5 is clear and the appropriatedata condition bits (B0, B3 and B4) are set. If the busy condition caused theSRQ, then only the busy bit is set.

After an SRQ, the status byte remains unchanged until it is read.

The various bits in the status byte are described below:

1. Reading Overflow-Set when an overrange input is applied to theinstrument.

2. Reading Done-Set when the instrument has completed the presentconversion, and is ready to take another reading.

3. Busy-The instrument is still executing a prior command and is not yetready to accept a new command.

4. IDDCO-An illegal command option such as R8 has been sent. This bitis cleared when the status byte is read.

5. IDDC-An illegal command sets this bit. For example, N1 is illegalsince no such letter exists in the command set. The IDDC bit is clearedon a reading of the status byte.

6. Not in remote-Model 835 is in local mode of operation.

Figure 3-7. Status Byte Format


36

Table 3-10. Status Byte and Mask Interpretation

Bit 5 = 0 Bit 5 = 1Bit (Data Conditions) (Error Conditions)

0 (LSB) Overflow IDDCO1 N/A IDDC2 N/A No remote3 Reading done N/A4 Busy N/A5 Data Error6 SRQ SRQ7 N/A N/A

N/A = Bit ignoredMnnn (nnn = 0 to 255, base 10)

Notes:1. Once the Model 835 generates an SRQ, its status byte must be read

to clear the SRQ line. (Otherwise, the instrument continuouslysends SRQ.)

2. The Model 835 may be programmed to generate an SRQ for morethan one condition simultaneously.

Programming Example - Enter the following program into the HP-85:

Program Comments

10 REMOTE 722 Set up for remote operation.20 OUTPUT 722; “M33X” Program for SRQ on IDDCO.30 OUTPUT 722; “A20X” Attempt to program illegal command option.40 S= SPOLL (722) Perform serial poll.50 DISP “B7B6B5B4B3B2B1B0”60 FOR I= 7 TO 0 STEP-1 Loop eight times70 DISP BIT (S,I);80 NEXT 190 DISP

100 END

Press the HP-85 RUN key. The computer conducts a serial poll and displaysthe status byte bits in order on the CRT. The SRQ (B6), error (B5), and IDDCO(B0) bits are set because line 30 of the program attempted to program theinstrument with an illegal command option (R8).

3.5.11 Data Format

Model 835 data is transmitted over the bus as a string of ASCII characters, inthe format shown in Figure 3-8. The first character indicates the function. Themantissa of the reading is made up of 7 characters, including sign and deci-mal point, while the exponent requires three characters. To obtain the datastring from the instrument, the controller must perform the following se-quence:

1. Set ATN low.2. Address the instrument to talk.3. Set ATN high.4. Input the data string one byte at a time.


37

NOTEThe data string can be sent without the prefix. For more information,refer to paragraph 3.5.12.

Figure 3-8. Data Format

output a data string.

Program Comments

10 REMOTE 722 Set for remote operation.20 ENTER 722;A$ Enter for command into computer.30 DISP A$ Display on CRT40 END

Press the run key of the HP-85 and the data string is displayed.

3.5.12 Prefix (G)

At use of the G command, the prefix for the status word or data string can beeither transmitted or deleted. The commands are as follows:

G0 = Include Prefix or Postfix.G1 = Suppress Prefix or Postfix.

After power-up, or after a DCL or SDC command, the G0 mode is enabled.

Programming Example - Program the Model 835 to output a data stringwithout the prefix or postfix.

Program Comments

10 REMOTE 722 Set for remote operation.20 OUTPUT 722; “G1X” Send prefix command.30 ENTER 722; A$ Enter command into computer.40 DISP A$ Display on CRT.50 END

Press the HP-85 run key. The data string is displayed without the prefix.


38

3.5.13 Programmable Terminator (Y)

The Model 835 uses special terminator characters to mark the end of its datastring or status word. To allow a wide variety of controllers to be used, theterminator can be changed by sending the appropriate command over the bus.The default value is the commonly used carriage return, line feed (CR LF)sequence. The terminator sequence will assume this default value at power-up, or after the instrument receives a DCL or SDC.

The terminator may be programmed by sending the ASCII character Y,followed by the desired character. Any ASCII character except one of thefollowing may be used:

1. Any capital letter.2. Any number.3. Blank4. + - / , . or e

Special command characters program the instrument for special terminatorsequences as follows:

1. Y(LF) = CR LF (Two terminators - Power Default)2. Y(CR) = LF CR (Two terminators)3. Y(DEL)= No terminator

NoteMost controllers use the CR or LF character to terminate their inputsequence. (Using a nonstandard terminator may cause the controllerto hang up unless special programming is used.)

Programming Example-The terminator can be eliminated by sending an ASCIIDEL with the following HP-85 statements:

REMOTE 722 (END LINE)OUTPUT 722;”Y”;CHR$(127);”X”(END LINE)

When END LINE is pressed the second time, the terminator is suppressed; noterminator will be sent by the instrument when data is requested. The ab-sence of the normal terminator may be verified by entering the followingstatement into the HP-85 keyboard.

ENTER 722;A$ (END LINE)

At this point, the HP-85 ceases to operate, because it is waiting for the stan-dard CR LF terminator sequence to terminate the ENTER statement. Thecomputer may be reset by holding down the SHIFT key and pressing RESETon the keyboard. To return the instrument to the normal terminator sequence,enter the following statement into the HP-85:

OUTPUT 722;”Y”;CHR$(10);”X” (END LINE)

3.5.14 Setting The Wavelength (W)

The calibration wavelength of the Model 835 can be set by sending the follow-ing over the bus:

W+nnnn

Where nnnn is the wavelength in nm to be set. The wavelength sent isrounded to the nearest 10nm increment. (For example, an input of W+1234 isrounded to 1230.)

Programming Example - Cycle power on the Model 835 and manually set


39

600 nm wavelength. If the detector is not calibrated for 600 nm, select anywavelength for which the detector is calibrated. Enter the following state-ments into the HP-85:

REMOTE 722 (END LINE)OUTPUT 722; “W+950X” (END LINE)

After END LINE is pressed the second time, the wavelength annunciatorindicates 950 nm and the appropriate calibration for 950 nm will be used.

NoteIf the detector is not calibrated for 950 nm, the detector (or attenuator)serial number will be displayed, and the wavelength annunciator turnsoff. Use this to obtain the detector/attenuator serial numbers.

3.5.15 Status Word (U0)

The status word commands allow access to information concerning presentoperating modes of the instrument. When the status word command is given,the Model 835 transmits status information - instead of its normal data stringthe next time it is addressed to talk. Model 835 status word command is:

U0 = Send instrument status on operating modes such as range, LOG, etc.

The general format for the U0 command is shown in Figure 3-9. The letters inthe U0 format correspond to other device-dependent commands, such asRANGE (R), LOG (D), etc.

Notes:

1. Status word information is returned only once each time the commandis sent. Once status is read, the instrument sends its normal data stringthe next time it is addressed to talk.

2. The returned terminator character (Y) is derived by ANDing the bytewith 00001111, and ORing the result with 00110000. For example, thelast byte in the normal (CR LF) terminator sequence is a LF or ASCII 10(00001010). ANDing with 00001111 yields 00001010. ORing with00110000 results in 00111010, which is printed out as an ASCII colon (:).

3. The status word should not be confused with the status byte. Thestatus word contains a number of bytes pertaining to the variousoperating modes of the instrument. The status byte is a single byte thatis read with the SPE, SPD, command sequence and contains informai-ton on SRQ status and error and data conditions.

4. The returned SRQ mode (M) value is determined, by adding up thevalues of the bit positions in the status byte that could cause an SRQ,according to the previously programmed value of th SRQ mode. Forcomplete information on the SRQ mask and status byte, refer to para-graph 3.5.10.

Programming Example - Enter the program below into the HP-85. Be sure toinclude line numbers.

Program Comments

10 REMOTE 722 Set up instrument for remote operation.20 OUTPUT 722; “U0X” Send U0 status command.30 ENTER 722; A$ Enter status word into computer.40 DISP A$ Display on CRT.50 END

After entering the program, press the HP-85 RUN key. The U0 status word is


40

Figure 3-9. General Format U0 Command


41

then displayed on the CRT.

3.5.16 Wavelength (U1)

The wavelength reading function is controlled by sending the followingcommand over the bus.

U1 = Read Wavelength

Wavelength information is in an alternate output string on talk. The wave-length (WAVE1000) string is in the form of WAVEnnnn where: nnnn repre-sents the wavelength.

The returned wavelength setting is in 10nm increments over the calibrationrange of the detector/attenuator.

The U1 wavelength transmission is automatically disabled when the normalSTATUS WORD (U0) is commanded (paragraph 3.5.15).

Programming Example - To display the wavelength, enter the program belowinto the HP-85. Be sure to include line numbers.

Program Comments

10 REMOTE 722 Set up instrument for remote operation.20 OUTPUT 722; “U1X” Send U1 wavelength command.30 ENTER 722; A$ Enter wavelength word into computer.40 DISP A$ Display on CRT.50 END

After entering the program press the HP-85 RUN key. The U1 status word isthen displayed on the CRT.

3.5.17 Serial Numbers Detector and Attenuator

Serial numbers of the detector or attenuator are returned after a “U1” com-mand if the wavelength set is outside of the calibration range. For setting thewavelength outside calibration limits, refer to paragraph 3.5.14.

If the Attenuator mode is On when U1 is executed, the attenuator serialnumber will be returned. Attenuator serial number is in the form:

SAT#nnnnn (nnnnn = 00001 to 09999)

If the Attenuator mode is Off when U1 is executed, the detector serial numberis returned in the form:

SPR#nnnnn (nnnnn = 00001 to 09999)

Programming Example - To read the detector serial number, attenuator off

Programming Comments

10 REMOTE 722 Set up instrument for remote operation20 OUTPUT 722 ; “A0XW+9000X” Attenuator off. Set wavelength out of

bounds30 ENTER 722 ; A$ Take reading40 DISP A$ Wavelength is out of bounds, so S/N

is displayed50 END


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Only Operation3.6Talker

The talker only mode may be used to send data to a listen only device such asa printer. When the Model 835 is in the talker only mode, it ignores com-mands given over the bus. The talker only mode is enabled by placing theTO/ADDRESSABLE switch in the TO position (Figure 3-6).

NOTEThe status of the TO/ADDRESSABLE switch is read-only at power-up.If the switch position is changed, the instrument must be momentarilypowered down before it recognizes the new switch condition. Sendingcommands to the instrument when it is in the talker only mode maycause the controller to hang up.

When the Model 835 is used in the talker only mode, it may be interfaced withone or more listeners. Each of these devices and associated cabling shouldconform to IEEE-488(1978 Standards).

The Model 835 transmits its normal data string in bit-parallel byte-serialfashion over the bus as requested by the listeners. (The data format is thesame one used for addressable operation and is described in detail in para-graph 3.5.11.) If the address switches are set to an odd number the prefix issent with the reading. An even address number sends only the data.

Every reading taken by the Model 835 will be send over the interface, or about5 to 6 readings per second. The listener must accept data at a high enoughrate or some characters of the transmitted data may not be received.


43

basic circuit description of the Model 835. The IEEE-488 interface optionenables the Model 835 to be used in a measurement system with programmcontrol through the IEEE-488 bus. Explanation of the complicated software isbeyond the scope of this section.

Introduction

This section contains the4.1

The entire IEEE-488 interface circuitry is located on a single PCB. The heart ofthe IEEE option is the General Purpose Interface Bus Adapter (U104) and themicroprocessor (U101). The GPIBA is capable of performing all IEEE Talker-Listener protocols. The bidirectional data lines DO through D7 permit thetransfer of data between the microprocessor and the GPIBA. The transceiverU105 and U107 are used to drive the output. Data is buffered by U105 andU107 and is transmitted to the bus via connector J1007.

The primary address switches (SW101) select the primary address, and permitselection of 31 primary Talker/Listener address pairs. To address the Model835 the controller must send the primary address of the Model 835. The factoryset primary address of the Model 835 is 22 (10110). The microprocessor readsthe primary address from S101 and then knows which Talker/Listener addressto assign the GPIBA (U104) and thus the Model 835.

NoteThe primary address is updated only at power up.

This function is accessed with the address switch enable (AS) signal. The ASsignal is derived from the microprocessor (U101) and enables the three statelatch U103. Enabling U103 places the address on the data bus (DO-D4 and D7).

The opto-isolators (U109 and U111) isolate the Model 835 from earth ground,which is available from the controller (or one of the instruments on theIEEE bus).

Circuit Description4.2

Section 4

Theory of Operation


44


45

Section 5

MaintenanceIntroduction

This secton con-tains information necessary to maintain the Model 835 Interface. Installationprocedures, troubleshooting information and instructions concerning care inhandling static sensitive devices is included. All service information isintended for qualified electronic maintenance personnel only.

Interface is field installable. To install the Model 835 Interface into a Model835, perform the following procedures and see Fig. 6-1.

WARNINGInstallation of the Model 835 Interface should only be performed byqualified electronic maintenance personnel. To prevent a shock haz-ard, unplug the line cord, and all test leads, from the instrument beforeremoving the top cover.

1. Remove and retain the top cover, rear panel and power cord. (The topcover is secured by four screws accessible from the bottom of the instru-ment.)

2. Install the rear standoff by positioning it over the hole in the PC board, asshown in Figure 6-1; and pressing firmly until it snaps securely into theboard.

3. Install the cable clamp so that there is no slack in the display cable underthe IEEE board. The display cable must not touch the IEEE board.

4. Position the Model 835 Interface loosely on the rear standoff.

WARNINGDo not push down on plug P1008, (on the left side as viwed from thefront) of the PC board. The male connector pins will pass through jackP1008 and may cause personal injury.

5. Guide the long pins of P1008 into J1008, then carefully and firmly pushdown on that end of the board to mate the connectors.

6. Carefully push down on the other side of the IEEE board, until it snapsonto the rear standoff. Make sure the board is seated securely and prop-erly on the front stand off.

7. Install modified back panel with cutout for IEEE connector, and connectpower cord connector onto PC board.

8. Install the modified top cover.

WARNINGIf the Model 835 Interface is subsequently removed, use the originalrear panel supplied with the Model 835 (if available). If the modifiedrear panel is used, cover the holes normally occupied by the IEEEconnector and switch. Failure to cover these holes could result in ashock hazard that can cause severe injury or death.

Installation

The Model 835

45

5.1

5.2


46

at high impedance levels. Normal static charge can destroy these devices. Allthe static sensitive devices for the Model 835 Interface are listed in Table 5-1.Following steps 1 through 7 provide instructions on how to avoid damagingthese devices.

1. Handle and transport the devices in protective containers, antistatic tubesor conductive foam.

2. Use a properly grounded work bench, and a grounding wriststrap.

3. Handle device by the body only.

4. While inserting devices, PC boards must be grounded to bench.

5. Use antistatic solder suckers.

6. Use grounded tip soldering irons.

7. After devices are soldered or inserted into sockets they are protected, andnormal handling can resume.

5.3Special Handling ofStatic SensitiveDevices

CMOS devices function


47

Section 6

Service

contains information about servicing the Model 835-IEEE Interface, andcomponent location drawings. The Model 835-IEEE Interface is designed tobe serviced by replacing the PC board, rear panel and power cord. Thismethod eliminates the need for the user to return the entire unit to the factoryfor repair. In some instances, however, field repair may be more appropriate.Contact Newport Corporation or your newport representative for assistance.

duction

This section

tion concerning factory service, contact the factory or your Newport represen-tative. Please have the following information available:

1. Instrument Model Number

2. Instrument Serial Number

3. Detector Serial Number and, if available, calibration date.

4. Attenuator Serial Number and, if available, calibration date.

5. Description of problem.

When returning the instrument to Newport, please complete the service formwhich follows this section and return it with the instrument, circuit board orparts.

6.1

Factory Service

To obtain informa-6.2


48

Installation & Compenent Location Drawings

Figure 6-1. Model 835-IEEE Interface Installation6.3

48

Figure 6-2. Model 835-IEEE Component Location Drawing


49


SERVICE FORM

Model No. ___________ Serial No. ______________ P.O. No. __________________ Date ______________ _

Name _________________________________________________________________________________________ _

Company______________________________________________________________________________________ _

Address _______________________________________________________________________________________ _

City_________________________________ State ____________________ Zip __________________________ _

Country _______________________________________________________________________________________ _

List all control settings and describe problem. ______________________________________________________ _

______________________________________________________________________________________________ _

______________________________________________________________________________________________ _

__________________________________________________________ (Attach additional sheets as necessary.)

Show a block diagram of your measurement system including all instruments connected (whether power isturned on or not). Also describe signal source.

Where is the measurement being performed? (factory, controlled laboratory, out-of-doors, etc.) ___________ _

______________________________________________________________________________________________ _

What power line voltage is used? ________________ Variation? _____________________________________ _

Frequency? ________ Ambient Temperature? _____________________________________________________ _

Variation? _ ˚F. Rel. Humidity? ______________________________ Other? __________________________ _

Any additional information. (If special modifications have been made by the user, please describe below.)

______________________________________________________________________________________________ _

______________________________________________________________________________________________ _

*Be sure to include your name and phone number on this service form.


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