A L W A Y S A T T H E F O R E F R O N T O F T E C H N O L O G Y

Instruction Manual

III

Simrad IS12Mega Instrument

M A N U A L

IS12 Mega

IV E04252 Issue 1.0 9/8/02 MDL

The technical data, information and illustrations contained in this publication were to the best of our knowledge correct at the time ofgoing to print. We reserve the right to change specifications, equipment, installation and maintenance instructions without notice aspart of our policy of continuous development and improvement.No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form, electronic or otherwise withoutprior permission from Simrad Ltd.No liability can be accepted for any inaccuracies or omissions in the publication, although every care has been taken to make it as com-plete and accurate as possible.

© 2002 Simrad Ltd

CONTENTS

1 GENERAL1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.2 IS12 Network System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2 OPERATION2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82.2 Data Page Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.2.1 Calibration & Settings . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.2 Display Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.3 Information Required . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.4 Cancelling Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.2.5 Apparent & True Wind Angle . . . . . . . . . . . . . . . . . . . 132.2.6 VMG (Velocity Made Good) . . . . . . . . . . . . . . . . . . . . 142.2.7 XTE (Cross Track Error) . . . . . . . . . . . . . . . . . . . . . . . 15

2.3 Backlighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.4 Remote Control Option . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3 CALIBRATION3.1 Page Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.2 Operation Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

3.2.1 IS12 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193.2.2 NMEA Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3.3 Local & Network Backlighting . . . . . . . . . . . . . . . . . . . . . . . . 213.4 Disable Remote Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

4 INSTALLATION4.1 Instrument Head Installation . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4.1.1 Front Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234.1.2 Rear Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

4.2 Electrical Installation - IS12 Mode . . . . . . . . . . . . . . . . . . . . . . 264.2.1 Network Termination . . . . . . . . . . . . . . . . . . . . . . . . . 274.2.2 NMEA Input/Output . . . . . . . . . . . . . . . . . . . . . . . . . 28

4.3 Electrical Installation - NMEA Mode . . . . . . . . . . . . . . . . . . . 294.4 Electronic Interference Suppression . . . . . . . . . . . . . . . . . . . . 30

5 APPENDIX5.1 Data Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315.2 NMEA Sentences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335.3 Fault Finding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345.4 Spares and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345.5 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.6 Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355.7 Service & Warranty . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Instruction Manual

V

1 GENERAL1.1 Introduction

The Simrad IS12 System is a flexible modular series of instru-ments that offer large, clear displays, easy to operate functionsand robust, weatherproof construction. The IS12 Mega is amultifunction data repeater that can display information fromany master IS12 unit in the system, or act as an NMEA repeater.

The IS12 Mega is supplied complete with a 5m data cable toenable it to be linked to an existing system. All functions areeasily accessed, thanks to IS12’s intuitive, user friendly controlsystem.

Thank you for choosing Simrad.

If you are pleased with your instrument we hope you will beinterested in our range of marine electronic equipment, whichis manufactured to the same high standards as IS12. Pleasecontact your nearest Simrad Agent for a catalogue showing ourincreasing range of high tech navigational instruments, GPS,autopilots, Radar, Fishfinders and VHF radio sets.

Simrad operate a policy of continual development and reservethe right to alter and improve the specification of their prod-ucts without notice.

IS12 Mega

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MEGA

LIGHT • •

Fig 1.1 - IS12 Mega Instrument

INFO

1.2 IS12 Network SystemThe IS12 system is built around a high speed bus networkingsystem that allows instruments to be easily interconnected andshare data.

All units are interconnected and powered using a standard sin-gle cable (Fig 1.2) -

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Additional instruments can be added to the system to act asrepeaters, for example at the chart table of a sailboat or the fly-bridge of a powerboat. Thus, as shown in the example above,the Mega instruments repeat the information from the maininstruments.

Fig 1.2 - IS12 Network System

COMBI

CONTROLLERALARM

DATA COMPASS

MEGAMEGA WIND

WIND Tx

COMPASS Tx

2 OPERATION2.1 General

The IS12 Mega is a large digit multifunction repeater that candisplay data either from any IS12 master unit (Fig 2.1) -

IS12 Mega

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or from other equipment via NMEA0183 (Fig 2.2) -

Fig 2.1 - Mega displays as IS12 system repeaters

Fig 2.2 - Mega displays as NMEA repeaters

MEGA MEGA MEGA

IS12 SPEED IS12 DEPTH IS12 WIND

Press the INFO key to cycle through the data pages on theMega instrument -

Boat Speed* ¬Log ¬Trip ¬Water Temperature ¬Average Speed ¬Maximum Speed ¬Race Start Timer ¬Depth* ¬ Shallow Alarm Setting ¬ Deep Alarm Setting ¬ AWA* - Apparent Wind Angle (0-180º) ¬ AWA - Apparent Wind Angle (0-90º relative to bow/stern) ¬AWS* - Apparent Wind Speed ¬TWA - True Wind Angle (0-180º) ¬ TWA - True Wind Angle (0-90º relative to bow/stern) ¬TWS - True Wind Speed ¬TWD - True Wind Direction ¬VMG - Velocity Made Good ¬High Wind Alarm Setting ¬MAGº* - Magnetic Compass Bearing ¬ TRUEº - True Compass Bearing ¬COG M - Course Over Ground (Magnetic) ¬COG T - Course Over Ground (True) ¬SOG - Speed Over Ground ¬BTW - Bearing To Waypoint ¬XTE - Cross Track Error ¬ *These pages are factory preset to “on” (see section 3.1).

NOTE Although Lat & Long cannot be displayed by the Mega, this data is converted to IS12 format and can be displayed on anyIS12 Data display in the system.

Data will only be displayed on a page if a master unit out-putting this information is linked to the Mega instrument. If thedata is not available, the instrument will show “---” (Fig 2.3) -

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Fig 2.3 - No data received

MEGA

IS12 Mega

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Individual data pages can be switched off if necessary to avoidhaving to cycle through pages that have no incoming data -refer to section 3.1 for further details.

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

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MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO

MEGA

LIGHT ••

MEGA

LIGHT •• INFO

MEGA

LIGHT •• INFO INFO

Fig 2.4 - All data pages available

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2.2 Data Page Information2.2.1 Calibration & SettingsNo control or calibration of the incoming data is possible. Toadjust any settings (eg depth alarms) or activate any functions(eg race countdown timer), use the relevant master unit.

2.2.2 Display UnitsThe units of measurement used on the data pages are dictatedby the incoming data - to change, select the required displayunits on the master unit.

2.2.3 Information RequiredSeveral of the data pages require information from two or moresources in order to process the data sentence - for example, tocalculate True Wind data, both Wind and Boat Speed informa-tion are required. Please refer to section 5.1 for full details ofthe incoming information required for each data page.

2.2.4 Cancelling AlarmsIf an alarm is triggered by a master unit, the Mega will switchto the relevant data page. The alarm will sound on the Megaand the alarm icon and top line of the display will flash (Fig2.5) -

MEGA

LIGHT • • INFO

To cancel the alarm, press any key.

NOTE Any alarms originating from an IS12 master unit will cancel themselves after 15 seconds, but if the incoming informationstill exceeds the alarm setting threshold, the alarm will triggerevery 30 seconds until cancelled.

Fig 2.5 - Alarm display

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2.2.5 Apparent & True Wind AngleThere are two display options for each of the above pieces ofdata. The first is a standard 0-180º display which shows thewind angle relative to the boat and the current tack (Fig 2.6) -

MEGA

LIGHT • •

Fig 2.6 - “Full” wind angle display

INFO

MEGA

LIGHT • •

Fig 2.7 - “Close Hauled” wind angle display

INFO

The second option shows the wind angle as 0-90º, relative tothe bow or stern of the boat (Fig 2.7) -

- ctd

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When showing the close hauled wind angle, the graphic on theleft of the display indicates the direction of the wind.

When sailing close hauled, the digits show the wind anglemeasured from the bow of the boat (Fig 2.8) -

When running, the digits show the wind angle measured fromthe stern, indicating how close the boat is to gybing (Fig 2.9) -

Running, starboard tackRunning, port tack

Close hauled, port tack Close hauled, starboard tack

Fig 2.8 - Wind direction indicator - Close Hauled

Fig 2.9 - Wind direction indicator - Running

2.2.6 VMG (Velocity Made Good)The VMG page is generated by the Mega itself. In order forthis information to be generated, Boat Speed, Apparent WindAngle and Apparent Wind Speed data are required.

The top line of the display will show “VMG” when close hauledand flashes “-VMG-” when running downwind (Fig 2.10) -

MEGA

Fig 2.10 - VMG display

MEGA

VMG Close Hauled (Upwind)

VMG Running (Downwind)

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2.3 BacklightingThe backlighting illuminates the display and the keys, withfive levels of brightness.

To switch the backlighting on, press the LIGHT key. The dis-play will illuminate and the large digits will show the currentlighting level (Fig 2.12) -

LIGHT • • INFO

Fig 2.12 - Turning Backlighting On

• INFO•LIGHT

2.2.7 XTE (Cross Track Error)The Cross Track Error (XTE) is the amount of deviation fromthe ideal track to the target waypoint displayed as a distancefrom the track.

The arrow on the top line of the display indicates the directionof the error from the track (Fig 2.11) -

MEGAWPT 2

WPT 1

0.41nm

Fig 2.11 - XTE display

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Press the (• RIGHT) key to increase the brightness (max 5),(• LEFT) to decrease it (min 1), (INFO) to accept the select-

ed brightness or (LIGHT) to turn the backlighting off.

NOTE While the backlighting is on, the lamp icon ( ) will be shown on the bottom left of the display.

The backlighting can either be Local or Network controlled. Localcontrol means that any adjustments to lighting will only affectthis specific instrument. With Network control, all instrumentsin the network will be affected. See Section 3.2 for more details.

2.4 Remote Control / Alarm OptionThe optional remote control allows all functions of each instru-ment to be remotely controlled. The keypad labelling corre-sponds directly with that of the Mega instrument (Fig 2.13) -

Fig 2.13 - IS12 Remote Control

Any alarms sounded are also repeated on the remote control.

If required, remote control functionality can be disabled on theMega instrument so that the Remote Control will “ignore” it.Refer to Section 3.3 for more details.

MEGA

LIGHT •• INFOSelectInstrument

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3 CALIBRATIONTo protect the calibration functions, these are held in a hiddenmenu. To enter calibration mode, press and hold the LIGHTkey (Fig 3.1) -

Once in calibration mode, pressing the (• LEFT) and(• RIGHT) keys will cycle through the available calibration

options -

- Page Configuration (Section 3.1)- Operation Modes - IS12/NMEA (Section 3.2)- Local / Network Backlighting (Section 3.3)- Disabling Remote Control Facility (Section 3.4)

To exit calibration mode, press and hold (LIGHT).

MEGA

LIGHT • • INFO

Fig 3.1 - Entering Calibration Mode

• INFO•LIGHT

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3.1 Page ConfigurationTo avoid having to scroll through data pages that have noincoming information, or to set the Mega to display only select-ed information available, individual data pages can be disabledusing this function.

Enter calibration mode - the display will show PAGES CAL -and press (INFO) . The current data page and its displaystatus will be shown (Fig 3.2) -

MEGA

LIGHT • • INFO

Fig 3.2 - Page configuration status

“On” indicates that this data page is currently enabled. Toscroll through the data pages and view their configuration sta-tus, press the and keys.

To toggle this page on/off, press INFO. With the page dis-abled, it will not be displayed when scrolling through the datapages.

Press to advance to the following data page.

Press LIGHT to accept the changes and exit to the calibrationmenu.

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3.2 Operation ModesThere are two modes of operation for the Mega instrumentdepending on the installation and equipment it is to be usedalongside.

3.2.1 IS12 Mode (Mode 1)This is for use when the Mega is to be used as part of an IS12instrument system. In this mode, the Mega will display the fol-lowing data -

- IS12 data present on the system- Processed* navigational data via the IS12 network- Incoming navigational data via NMEA0183

* i.e any nav data received and converted to IS12 data format by another piece of equipment

on the network.

In this mode, any third party navigational master units con-nected to the Mega via the NMEA In terminals will be repeatedby the Mega display and this data will then be passed onto theIS12 network. Incoming NMEA instrument data (i.e speed,depth, wind etc) cannot be displayed.

NOTE Only one instrument can receive NMEA data in an IS12instrument system.

NOTE If the same item of data is already available on the IS12network then the incoming NMEA sentence is not processed -IS12 network data always takes precedence over NMEA data.

The NMEA Out terminals will transmit the following data -

- IS12 instrument data

Fig 3.3 - Installation example - IS12 Mode

NMEA InNav Data

NMEA OutInstrument Data

IS12Instrument Data

& ConvertedNav Data

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3.2.2 NMEA Mode (Mode 2)This mode should be selected if the Mega instrument is to beused as an NMEA data repeater with no IS12 master units. Inthis mode, the Mega will display the following data -

- NMEA0183 instrument data- NMEA0183 navigational data

In this mode only the NMEA terminals are used to link theMega to any master units - the network ports are only used tosupply power to the display. No data is received or transmittedto any IS12 units connected to the Mega via the network ports.

The NMEA Out terminals will retransmit the following data -

- NMEA0183 instrument data- NMEA0183 navigational data

NMEA InInstrument & Nav Data

NMEA OutInstrument & Nav Data

Fig 3.3 - Installation example - NMEA Mode

12v

in

To switch between IS12 & NMEA modes, enter calibrationmode and press once (the display will show “MODE CAL”.Press (INFO) to accept.

The large digits on the display will show “1” for IS12 Mode or“2” for NMEA Mode. Press or to change modes then to accept and return to the calibration menu.

NOTE Press to exit to the main calibration menu at any point.

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3.3 Local & Network BacklightingThe backlighting can be set so that any changes made areduplicated across the system (Network), or so that any changesare limited to the specific instrument only (Local). The IS12instruments are set to Networked lighting as default.

Enter calibration mode, press once (the display will showLIGHT CAL) and press (INFO).

The top line will show the current setting - NET for Networkedor LOC for Local. The setting can be changed using the or keys (Fig 3.4) -

LIGHT • INFO

Fig 3.4 - Changing from Network to Local Backlighting

•

To set the selected backlighting, press . The display will thenreturn to the main calibration menu.

NOTE Press to exit to the main calibration menu at any point.

NOTE Any changes will affect this specific instrument only.

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3.4 Disable Remote ControlOn some installations which includes the IS12 Remote Control,it may be more convenient to limit remote control access toonly some instruments on the network - for example on a fly-bridge power boat with a set of instruments on both steeringstations, it would not be desirable to be able to control theinstruments on the flybridge (Fig 3.5) -

To disable Remote control functionality on this instrument,enter calibration mode, press twice (the display will showCTRL CAL) and press (INFO).

The large digits will show the current setting - ON for remotecontrol enabled or OFF for remote control disabled. The set-ting can be changed using the or keys.

To set the selected mode, press . The display will then returnto the main calibration menu.

NOTE Press to exit to the main calibration menu at any point.

NOTE Any changes will affect this specific instrument only.

For further information on Remote Control operation, pleaserefer to the user manual supplied with the Remote Control /Alarm unit.

Main Steering Station

Flybridge

Rear mounted instruments - remote control required.Remote control enabled

Front mounted instruments - no remote control requiredRemote control disabled

Fig 3.5 - Flybridge system with Remote control of main steering sys-tem only

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4 INSTALLATION4.1 Instrument Head Installation

All IS12 instrument heads are a standard 110 x 110mm (4.3x4.3in) size, and can be mounted either from the front or the rear.

4.1.1 Front Mounting

Fig 4.1 - Front Mounting

Fig 4.2 - Clearance RequiredBehind Bulkhead

Front mounting (Fig 4.1) is the standard method of fitting andis the most straightforward. When mounting the instrumenthead it is important to ensure that there is adequate clearancebehind the bulkhead for the rear of the instrument with thecables inserted - allow at least 65mm (2.5 in) clearance (Fig 4.2).

Additionally, the instrument should not be fitted to a surfacethat has a curve greater than 1mm (1⁄25 in) across the mountingarea. If fixing to an uneven surface, care should be taken notto overtighten the screws. When choosing a location, consider-ation should be given to the water integrity of the gasket seal ifthe surface is not flat. IS12 is designed to be weatherproof, butthe rear of the instrument case with its electrical connectionsshould be protected from moisture as far as possible.

Tools required for installation -

-Drill- 85mm (3.4in) hole saw- 2.5mm (0.09in) drill bit- Countersinking bit

Using the self adhesive template supplied, drill the centralaperture for the instrument case using the hole saw, then thefour fixing holes as indicated on the template. If the instru-ments are to be fixed to a GRP bulkhead, the fixing holesshould be countersunk after drilling, to stop the screws split-ting the gelcoat. ctd -

65mm (2.5in)minimum

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The instrument is 110mm (4.33 in) square, but a distance of atleast 6mm (0.25 in) should be allowed between adjacent unitsfor the protective instrument cover supplied.

NOTE Long term exposure to direct sunlight can damage the liquid crystal display if left unprotected when not in use - always usethe instrument cover supplied.

The easiest way to fit the keypad and the bezel to the installedinstrument head is to locate the keypad in the keyholes in thebezel and then offer this up to the instrument head, angling thebezel back slightly to prevent the keypad falling out. The bezelshould click into place when located correctly (Fig 4.3) -

To remove the bezel, simply lift the top edge of the bezelslightly to disengage the locking clips and pull away from theinstrument head (Fig 4.4) -

Fig 4.3 - Fitting Keypad and Bezel

Fig 4.4 - Removing Bezel

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4.1.2 Rear MountingWhen the instrument is rear mounted, only the display can beseen - the main body of the instrument, including the keypad ishidden behind the panel. This is a more elegant method ofinstallation, but does require precise cutting of the apertures intothe bulkhead or dashboard. Therefore, it is recommended thatinstallation is done by a professional marine installer.

The instrument can be fixed to the panel using either the selftapping screws supplied (if the panel is thick enough), or using2mm studs fixed to the rear of the panel which align with thefour fixing holes (Fig 4.5).

Tools required for installation -

- Drill- 5mm (0.2in) drill bit- Fretsaw- A fine toothed file.

To assist in cutting a precise aperture for the display, a selfadhesive template is supplied with the unit (Fig 4.6) -

Fix the template in the correct position and drill four 5mmholes on the waste side of the four corners of the aperture.Starting from one of these holes, carefully cut along the dottedline around the four edges. To ensure the hole is a good fit, cutslightly inside the line (on the waste side) and then use the fileto smooth the edges until the display fits precisely.

NOTE Because the keypad is not accessible with this method of mount-ing, the Remote Control unit (see Section 2.6) will be requiredto enable control of instrument functions.

Fig 4.5 - Rear Mounting

Fig 4.6 - Cutting Aperture

Cut onwaste sideof template

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Fig 4.7 - IS12 “Daisychain” Cable System

4.2 Electrical Installation - IS12 Mode (Mode 1)IS12 instruments are ‘daisy chained’ together, with each instru-ment linking to the previous one by a single cable carryingpower and data (Fig 4.7). The cable plugs into either of the twocircular network ports on the rear of the instrument.

The cable connectors are keyed so that they will always be cor-rectly oriented when inserting the cable into the instrument -the flattened edge of the connector should be facing downwhen inserting (Fig 4.8) -

Fig 4.8 - Rear Connections

Flattened edge

Network Bus Ports

The first link in the IS12 system is the power cable, whichshould be connected to the boat’s 12v DC supply via a 3 Ampbreaker or fuse as follows -

Red wire - 12v DCBlack wire - 0v

NOTE Only one power cable is required in an IS12 system, but power must be supplied via the correct power cable (with a redconnector end), or the system will not function.

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4.2.1 Network TerminationThe IS12 system is based around a high speed data bus net-work. Although this is very robust, on very large or complexsystems with many instruments the system may need to beproperly terminated to ensure the integrity of the network. Forthis purpose a network terminator (Fig 4.9) is supplied withsome IS12 instruments, including the IS12 Mega. The termina-tor simply plugs into the last free network port in the daisy-chain. The terminator only needs to be fitted under certain cir-cumstances -

The terminator is not required if -a) The Mega instrument is used only as an NMEA repeaterunit and is not connected to other IS12 instrumentsb) There is already a terminator fitted to the system. Thereshould only be one terminator fitted per system.c) The system includes an IS12 Wind Transducer. The WindTransducer has an inbuilt network terminator.d) The total system cable length (excluding the power cable)is less than 5m. A small IS12 system does not require a termina-tor.

If the installation does not meet any of the above criteria, theterminator should be fitted to the spare network port at the endof the longest cable run.

A three way cable joiner (part no. SDJ) is available as a sepa-rate accessory. Any unterminated spurs created using the SDJmust be less than 5m in length (Fig 4.10) -

Fig 4.10 - Creating cable spurs using SDJ three way joiner

Three WayJoiner SDJ

Spur -max cablelength 5m

Spur -max cablelength 5m

Terminator fitted toend of longest spur

Fig 4.10 - Network Terminator

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4.2.2 NMEA Input/OutputThe Mega instrument features an NMEA0183 input and outputand is interfaced to external equipment using the crimp termi-nals supplied. To ensure a good connection when fitting theterminals to the interface cable, fold back the exposed wiresover the insulation before inserting into the terminal (Fig 4.11).Use a good quality crimp tool to crimp the terminals.

The two terminals on the rear of the unit (Fig 4.12) markedNMEA OUT + (Data) and NMEA OUT - (Common) should beconnected to the NMEA IN connections of the interfaced equip-ment.

The two terminals marked NMEA IN + (Data) and NMEA IN -(Common) should be connected to the NMEA OUT connec-tions of the interfaced equipment.

Fig 4.12 - NMEA Connections - IS12 Mode

When in IS12 Mode, the Mega can receive and display incom-ing navigational data via NMEA (not NMEA instrument data)and will output IS12 instrument data (depending on the mas-ter units in the system). For further details of NMEA sentencesreceived/transmitted, see Section 5.2.

NOTE Only one instrument per IS12 system can input NMEA data.

Fold wireend back

Ensure bare wiresare not visible

Fig 4.11 - Crimp Terminals

NMEA InNav data to be dis-

played on the Mega

NMEA OutInstrument data from theMega to an external unit

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4.3 Electrical Installation - NMEA Mode (Mode 2)The Mega instrument can be used as a stand alone (i.e not partof an IS12 system) repeater in conjunction with any third-partyequipment outputting/receiving the correct NMEA0183 for-mat. If using the Mega in this way, the operation mode shouldbe set to NMEA (2) - see section 3.2.

When in NMEA Mode the Network Ports’ only function is topass power to the Mega - no data is received or transmittedthrough these. The power cable supplied with the Megashould be plugged into one of the ports and connected to theboat’s 12v DC supply via a 3 Amp breaker or fuse as follows -

Red wire - 12v DCBlack wire - 0v

The Mega is interfaced to external equipment using the crimpterminals supplied. To ensure a good connection when fittingthe terminals to the interface cable, fold back the exposed wiresover the insulation before inserting into the terminal (Fig 4.13).Use a good quality crimp tool to crimp the terminals.

The two terminals on the rear of the unit (Fig 4.14) markedNMEA OUT + (Data) and NMEA OUT - (Common) should beconnected to the NMEA IN connections of the interfaced equip-ment.

The two terminals marked NMEA IN + (Data) and NMEA IN -(Common) should be connected to the NMEA OUT connec-tions of the interfaced equipment.

NMEA InInstrument & Nav Data

NMEA OutInstrument & Nav Data

Fig 4.14 - NMEA Connections - NMEA Mode

Fold wireend back

Ensure bare wiresare not visible

Fig 4.13 - Crimp Terminals

12v in - IS12Power Cable

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When in NMEA Mode the Mega can receive and displayinstrument and navigational data input via the NMEA IN ter-minals. This data will also be re-transmitted through theNMEA OUT terminals.

NOTE If there is more than one Mega instrument installed on the boat, the units should be interconnected as shown in Fig 4.15 -

NMEA In

NMEA Out

NMEA In

NMEA Out

IS12 InterconnectCable (This suppliespower only)

12v in - IS12Power Cable

Fig 4.15 - Multiple instrument interconnection - NMEA Mode

For further details of NMEA sentences received/transmitted,see Section 5.2.

4.4 Electronic Interference SuppressionIS12 has been designed to minimise the effects of interferencegenerated by the engine alternator. However, precautionsshould still be taken by routing the cables away from theengine compartment. Do not run the cables down trunkingcarrying high current cables. The transducer cable should alsobe kept separate from the boat’s radio antenna cable.

Engines with spark ignition, also some refrigerators should befitted with suppressors. Your local agent should be able toadvise on this and supply suppression kits where necessary.

Instruction Manual

31E04252

5 APPENDIX5.1 Data Required

This section details the equipment/incoming NMEA datarequired for each data page to function -

Boat SpeedMode 1 - An IS12 Speed or Combi instrumentMode 2 - VHW

LogMode 1 only - An IS12 Speed or Combi instrument

TripMode 1 only - An IS12 Speed or Combi instrument

Water TemperatureMode 1 - An IS12 Speed or Combi instrumentMode 2 - MTW

Average SpeedMode 1 only - An IS12 Speed or Combi instrument

Maximum SpeedMode 1 only - An IS12 Speed or Combi instrument

Race Start TimerMode 1 only - An IS12 Speed or Combi instrument

DepthMode 1 - An IS12 Depth or Combi instrumentMode 2 - DPT or DBT

Shallow Alarm SettingMode 1 only - An IS12 Depth or Combi instrument

Deep Alarm SettingMode 1 only - An IS12 Depth or Combi instrument

AWA - Apparent Wind AngleMode 1 - An IS12 Wind transducerMode 2 - VWR or MWV

AWS - Apparent Wind SpeedMode 1 - An IS12 Wind transducerMode 2 - VWR or MWV

TWA - True Wind AngleMode 1 - IS12 Speed or Combi plus Wind transducerMode 2 - VWR & VHW, MWV (R) & VHW or MWV(T)

-ctd

IS12 Mega

32 E04252

TWS - True Wind SpeedMode 1 - IS12 Speed or Combi plus Wind transducerMode 2 - VWR & VHW, MWV (R) & VHW or MWV(T)

TWD - True Wind DirectionMode 1 - IS12 Wind and Compass transducersMode 2 - HDG plus - VWR & VHW, MWV(R) & VHW

or MWV(T)

VMG - Velocity Made GoodMode 1 - IS12 Speed or Combi plus Wind transducerMode 2 - VHW plus - VWR or MWV(R)

High Wind Alarm SettingMode 1 only - An IS12 Wind transducer & instrument

MAGº - Magnetic Compass Bearing Mode 1 - An IS12 Compass transducerMode 2 - HDG or VHW

TRUEº - True Compass BearingMode 1 - An IS12 Compass transducer & instrument

with magnetic variation data enteredMode 2 - HDG or VHW (with magnetic variation data

entered in master unit)

COG M - Course Over Ground (Mag)Mode 1 - An IS12 Compatible GPS/Chartplotter or

VTGMode 2 - VTG

COG T - Course Over Ground (True)Mode 1 - An IS12 Compatible GPS/Chartplotter with

magnetic variation data entered orVTG, RMA, or RMC

Mode 2 - VTG, RMA, or RMC

SOG - Speed Over GroundMode 1 - An IS12 Compatible GPS/Chartplotter or

VTG, RMA or RMCMode 2 - VTG, RMA or RMC

BTW - Bearing To WaypointMode 1 - An IS12 Compatible GPS/Chartplotter or

BWR or BWCMode 2 - BWR or BWC

XTE - Cross Track ErrorMode 1 - An IS12 Compatible GPS/Chartplotter or

XTE or RMBMode 2 - XTE or RMB

Instruction Manual

33E04252

5.2 NMEA SentencesThe following NMEA sentences are transmitted/received bythe Mega instrument -

Mode 1 (IS12 Mode)Received DataVTG Course over ground (mag & true), speed over groundRMA Speed & course over groundRMB Cross track error & bearing to waypoint (T)RMC Speed & course over groundBWR Bearing to waypoint (rhumb line)BWC Bearing to waypoint (great circle)GLL Geographic position (Lat/Long)XTE Cross track error

Transmitted DataVHW Boat speed & heading (mag & true)MTW Water temperatureDBT Water depthDPT Water depth inc. offsetMWV Apparent wind angle & speedHDG Heading (mag & true)

Mode 2 (NMEA Repeater Mode)Received DataVHW Boat speed & heading (mag & true)MTW Water temperatureDPT Water depth inc. offsetMWV Apparent & true wind angle & speedHDG Heading (mag & true)VTG Course over ground (mag & true), speed over groundVWR Apparent wind angle & speedRMA Speed & course over groundRMB Cross track error & bearing to waypoint (T)RMC Speed & course over groundBWR Bearing to waypoint (rhumb line)BWC Bearing to waypoint (great circle)GLL Geographic position (Lat/Long)XTE Cross track error

Transmitted DataIn Mode 2, all NMEA data received is re-transmitted to NMEA Out.

IS12 Mega

34 E04252

5.3 Fault FindingSymptom Possible Cause Remedy

No display on any heads • Faulty connection to power • Check power connectionin the system • Fuse has blown • Replace fuse and check

power supply current

No display on one or • IS12 data cable loose or broken • Check cable linked tomore heads in system first faulty unit. Replace if

necessary

Occasional poor • Electrical interference from other • Fit interference suppressorsperformance equipment on boat to equipment responsible

Display shows “---” • Master unit not present in system • Mega can only repeat data• Required NMEA sentence not that is available on network

available• Faulty connection to master unit • Check data cable links

No NMEA Input/Output • NMEA connections reversed • Check NMEA connections

These simple checks should be carried out before seeking tech-nical assistance and may save time and expense. Before contact-ing your servicing agent please note the unit’s serial number.

5.4 Spares & AccessoriesThe following spares and accessories are available from localSimrad agents. Please quote part number when ordering -

IS12Mega:R Extra Mega Repeater Display

IS12Data:R Digital Repeater (two line)

IS12Remote:F Remote Controller

SPC2M Power Cable 2m

SDC0.3M IS12 Cable 0.3m

SDC02M IS12 Cable 2m

SDC05M IS12 Cable 5m

SDC10M IS12 Cable 10m

SDJ Three Way Cable Joiner

STP Spare Network Terminator

PIC Spare Instrument Cover

ISPK07 Spare Bezel & Keypad Pack - Mega

Instruction Manual

35E04252

5.5 Dimensions

20mm(0.78in)

17mm(0.67in)

110mm (4.3in)

110m

m (

4.3i

n)5.6 Specification

Supply Voltage 12v (9-16v) DC

Current Consumption Light Off - 40mA Light On - 60mA

NMEA Format Compliant with NMEA0183 versions2.0, 2.3 & 3.0 (4800 baud, no parity,8 bits, 1 stop bit)

Max units per system 32

Ambient Temp Range -10ºC to +55ºC (14ºF to 140ºF)

5.7 Service & WarrantyYour equipment should seldom need servicing, although it willbenefit from an application of silicone or Teflon grease to thecontacts each season.

The unit is guaranteed for 2 years from date of retail sale. If it isnecessary to have the unit repaired, return it carriage prepaid tothe agent in the country of purchase with a copy of the receiptedinvoice showing the date of purchase. Where possible, returnall the components unless you are certain that you have locatedthe source of the fault. If the original box is not available, ensurethat it is well cushioned in packing; the rigours of freight han-dling can be very different from the loads encountered in themarine environment for which the unit is designed.

For Worldwide Warranty details, please refer to the WarrantyCard supplied with this unit.

A L W A Y S A T T H E F O R E F R O N T O F T E C H N O L O G Y

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