When choosing the type of input or outputmodule for your system (orDL05/DL06/DL105 I/O type), it is veryimportant to have a solid understanding ofsinking and sourcing concepts. Use ofthese terms occurs frequently in discussionof input or output circuits. It is the goal ofthis section to make these concepts easy tounderstand, so you can make the rightchoice the first time when selecting the typeof I/O points for your application. Thissection provides short definitions, followedby general example circuits.

First you will notice that the diagrams onthis page are associated with only DCcircuits and not AC, because of the refer-ence to (+) and (-) polarities. Therefore,sinking and sourcing terminology appliesonly to DC input and output circuits. Inputand output points that are sinking orsourcing can conduct current in one direc-tion only. This means it is possible toconnect the external supply and fielddevice to the I/O point, with current tryingto flow in the wrong direction, and thecircuit will not operate. However, thesupply and field device can be connectedevery time based on an understanding ofsourcing and sinking.

The figure below depicts a sinking input.To properly connect the external supply, itmust be connected so the input provides apath to supply common(-). So, start at thePLC input terminal, follow through theinput sensing circuit, exit at the commonterminal, and connect the supply (-) to thecommon terminal. By adding the switchbetween the supply (+) and the input, thecircuit is completed. Current flows in thedirection of the arrow when the switch isclosed.

By applying the circuit principles to the fourpossible combinations of input/outputsinking/sourcing types, there are fourcircuits, as shown above. The commonterminal is the terminal that serves as thecommon return path for all I/O points inthe bank.

Sink/source I/O circuits combine sinkingand sourcing capabilities. This means thatthe I/O circuitry in the PLC will allowcurrent to flow in either direction, as shownat the right. The common terminalconnects to one polarity, and the I/O pointconnects to the other polarity (through thefield device). This provides flexibility inmaking connections to your field powersupply. Please note:

• Wire all I/O points with a shared common as either sinking or sourcing.

• Do not use an AC power supply on a DC sink/source I/O point.

1 - 8 0 0 - 6 3 3 - 0 4 0 530–2 Appendix

+

--

InputSensing

PLCInput

Common

(s inking)

+

--

InputSensing

Load

S inking Input(IE C: pos itive logic)

S inking Output(IE C: negative logic)

S ourcing Input(IE C: negative logic)

S ourcing Output(IE C: pos itive logic)

PLC

Input

Common

+

--

OutputSwitch

PLC

Output

Common

+

--

InputSensing

LoadPLC

Input

Common

+

--

OutputSwitch

PLC

Output

Common

PNP

NPN

S ink/S ource Input(IE C: pos ./neg. logic)

S ink/S ource Output(IE C: pos ./neg. logic)

+

--InputSensing

Load

PLC

Input

Common

OutputSwitch

PLC

Output

Common

+

--OR

+

-- +

--ORPNP/NPN

Sinking and Sourcing ConceptsSinking = provides a path to supply common (-)

Sourcing = provides a path to supply source (+)

24VDC

+

–

Output Sensor

Common

Input

OpticalIsolator

Current SourcingConfiguration

(NPN) Current SinkingField Device

DC Sourcing Input Module+ –

NPN (Sinking)Field Device Example

24VDC

+

–

Output Sensor

Common

Input

OpticalIsolator

Current SinkingConfiguration

(PNP) Current SourcingField Device

DC Sinking Input Module+ –

PNP (Sourcing)Field Device Example

Field device examples - 3 wire connections

w w w . a u t o m a t i o n d i r e c t . c o m Appendix 30–3

PLC Overview

DL05/06 PLC

DL105 PLC

DL205 PLC

DL305 PLC

DL405 PLC

Field I/O

Software

C-more HMIs

Other HMI

AC Drives

Motors

Steppers/Servos

Motor Controls

ProximitySensors

Photo Sensors

Limit Switches

Encoders

CurrentSensors

Pushbuttons/Lights

Process

Relays/Timers

Comm.

TB’s & Wiring

Power

CircuitProtection

Enclosures

Appendix

Part Index

Sinking and Sourcing ConceptsCommon terminals and how to use themIn order for a PLC I/O circuit to operate,current must enter at one terminal andexit at another. This means at least twoterminals are associated with every I/Opoint. In the figure at the right, the inputor output terminal is the main path for thecurrent. One additional terminal mustprovide the return path to the powersupply. Together, the main path and thereturn path create a loop, or a completecircuit for current to flow.

If there was unlimited space and budgetfor I/O terminals, then every I/O pointcould have two dedicated terminals.However, providing this level of flexibilityis not practical or even necessary for mostapplications. So, most input or outputpoints on PLCs are in groups that sharethe return path (called commons). Thefigure at the right shows a group (orbank) of four input points that share acommon return path. In this way, the fourinputs require only five terminals insteadof eight.

NOTE: Assuming all input circuits have a similarresistance, the current at the common terminal isfour times greater than the current at any one of theinputs. This effect is especially important to note foroutput circuits, where the current through a commonterminal can reach several amperes. You will needto decide whether to fuse each output point individu-ally, or to put a fuse in the common terminal path.

Wiring labels and how to interpret themDL205, DL305, DL405 - Most DL205,DL305 and DL405 input and outputmodules group their I/O points intobanks that share a common return path.The best indication of I/O commongrouping is on the wiring label, such asthe one shown at the right. The miniatureschematic shows two circuit banks witheight input points in each. The commonterminals are labeled “CA” and “CB,”respectively.

In the wiring label example, the positiveterminal of a DC supply connects to thecommon terminals. Some of the symbolsyou will see on wiring labels and theirmeanings are shown at the right.

DL05/DL06/DL105 — Most DL05, DL06and DL105 input and output circuits are

grouped into banks that share a commonreturn path. The best indication of I/Ocommon grouping is on the wiring label.Sample DL05, DL06 and DL105 wiringlabels and their meanings are shownbelow.

+

--

I/OCircuit

PLC

(I/O Point)

Return Path

FieldDevice

Main Path

+

--

InputSensing

Input 4

Common

Input 3

Input 2

Input 1

I/O Common Grouping Bar (DL105)

Two banks of four inputs and one bank of two (DL105)

Two banks of four inputs and two banks of three outputs (DL05)

Input Bank (DL05)

0123

4567

ATB

12--24VDC

D4--16ND2

0123

4567

B

INPUT

CA0

4

15

26

37

CB

40

51

62

73

10.2-- 26.4VDC4-- 12mA

L

AC supply

AC or DC supply

Input S witch

Output Load

DC supply+--

DL405 inputmodule shown

w w w . a u t o m a t i o n d i r e c t . c o m Appendix 30–7

PLC Overview

DL05/06 PLC

DL105 PLC

DL205 PLC

DL305 PLC

DL405 PLC

Field I/O

Software

C-more HMIs

Other HMI

AC Drives

Motors

Steppers/Servos

Motor Controls

ProximitySensors

Photo Sensors

Limit Switches

Encoders

CurrentSensors

Pushbuttons/Lights

Process

Relays/Timers

Comm.

TB’s & Wiring

Power

CircuitProtection

Enclosures

Appendix

Part Index

Throughout the world, there is a widevariety of regulatory codes, agencyapprovals, and other types of certificationthat may be required in order to install anautomation system. These requirementsvary and depend on your exact locationand situation. For example, there may benational codes, state and local govern-ment codes, and even wide-rangingrequirements such as the European Union(EU) Directives. The following are someof these codes and requirements, andexplanations of how they may affect youas a PLC and industrial controls user.

ISO 9001Some companies require their suppliersto use products that are built by compa-nies that adhere to a documented set ofquality-related procedures. ISO 9001 isone of the standards in the ISO 9000family of standards for quality manage-ment systems. Koyo Electronics IndustriesCompany, Ltd., the manufacturer of mostof our PLC products, is an ISO 9001certified company, as are many of ourother Federation members. Some copiesof the ISO certificates are available onour Web site.

Underwriters Laboratories(UL/CUL)Underwriters Laboratories is one of theworld’s premier safety testing and certifi-cation sources. Many applications requireUL approval for insurance and/or othercompliance purposes. There are severalareas of interest, but the most applicableare: UL508, the standard for IndustrialControl Equipment; and UL1604, thestandard covering Hazardous Locations.For more information on the UnderwritersLaboratories, check their Web site atwww.ul.com. There are several tables inthis section that show which of our prod-ucts have a UL listing. (They also indicatethe cUL approval, which is required inmany applications in Canada.) Pleasecheck our Web site for the most currentinformation.

European Union (EU) DirectivesThis area of certification and approval isabsolutely vital to anyone who wants todo business in Europe. One of the keytasks that faced the EU member countriesand the European Economic Area (EEA)was the requirement to bring severalsimilar, yet distinct, standards together

into one common standard for allmembers. The primary purpose of asingle standard was to make it easier tosell and transport goods between thevarious countries and to maintain a safeworking and living environment. TheDirectives that resulted from this “harmo-nization” of standards are now legalrequirements for doing business inEurope. Products that meet theseDirectives are required to have a CE markto signify compliance. A few key questionsare always asked when the subject of CEis discussed.

Which Directives apply to me? SeveralDirectives apply to our products, andDirectives may be amended or added, asrequired.

• Electromagnetic CompatibilityDirective (EMC) – Provides a means toensure that products placed on the mar-ket do not generate electromagnetic dis-turbances that would affect other appara-tus, including radio and/or telecommuni-cations equipment.

• Machinery Safety Directive – Covers thesafety aspects of the equipment, installa-tion, etc. There are several areasinvolved, including testing standards cov-ering both electrical noise immunity andnoise generation.

• Low Voltage Directive – Is also safetyrelated and covers electrical equipmentthat has voltage ranges of 50-1,000 VACand/or 75-1,500 VDC.

• Battery Directive – Covers the produc-tion, recycling, and disposal of batteries.

Who is responsible for ensuring compli-ance with these Directives? Ultimately, weare all responsible for our various piecesof the puzzle. Manufacturers must testtheir products and document any testresults and/or installation proceduresnecessary to comply with the Directives.As a machine builder, you are responsiblefor installing the products in a mannerthat will ensure compliance is maintained.You are also responsible for testing anycombinations of products that may (ormay not) comply with the Directives whenused together. The end user of the prod-ucts must comply with any Directives thatmay cover maintenance, disposal, etc. ofequipment or various components.Although we strive to provide the bestassistance available, it is impossible forus to test all possible configurations of theproducts we carry with respect to anyspecific Directive. Because of this, it is ulti-mately your responsibility to ensure thatyour machinery (as a whole) complieswith these Directives and to keep up withapplicable Directives and/or practices

that are required for compliance.

Which DirectLOGIC products carry theCE label? As of March, 2002, selectedDL05, DL06, DL205, DL305, DL405 andTerminator I/O PLC systems manufac-tured by Koyo Electronics Industries, HostEngineering or FACTS Engineering, whenproperly installed and used, conform tothe Electromagnetic Compatibility (EMC),Low Voltage Directive, and MachineryDirective requirements of the standardson the next page.

EC 61000-3-2 Power FactorCorrection The IEC 61000-3-2 standard is intendedto reduce the amount of disturbance adevice feeds back into its power source.AutomationDirect power supplies all carrythe CE mark. Normally, 61000-3-2 is metor does not apply. Only our PS24-150Dand PS24-300D could potentially beused in a manner not compliant with the61000-3-2 standard.

RoHSThe Restriction of Hazardous Substances(RoHS) Directive 2002/95/EC [1] wasadopted in February 2003 by the EU. TheRoHS directive, which took effect July 1,2006, restricts the use of six hazardousmaterials in the manufacture of varioustypes of electrical and electronic equip-ment. RoHS is linked with the WasteElectrical and Electronic EquipmentDirective (WEEE) 2002/96/EC which setscollection, recycling and recovery targetsfor electrical goods and is part of alegislative initiative to solve the problemof large amounts of toxic e-waste.

Each EU member state will adopt its ownenforcement and implementation policiesusing the directive as a guide. Therefore,there could be as many different versionsof the directive as there are states in theEU.

RoHS is often referred to as the lead-freedirective, however, it restricts the use ofthe following six substances:

•Lead•Mercury•Cadmium•Hexavalent chromium (chromium VI or

Cr 6+)•Polybrominated biphenyls (PBB)•Polybrominated diphenyl ether (PBDE)

For a listing of all products and theircompliance status see:

http://support.automationdirect.com/compliance.html#rohs

ISO 9001/UL/CUL/EU/RoHS