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What does a Module Fault (MOD_FLT) value of 2 mean for Modicon X80 Discrete Input/Output Modules?

Published date: 16 July 2019

Issue
What does a Module Fault (MOD_FLT) value of 2 mean for Modicon X80 Discrete Input/Output Modules?

Product Line
Modicon X80 - Discrete Input / Output Modules

Environment
PLC Configuration software:
EcoStruxure Control Expert
Unity Pro

Cause
A MOD_FLT byte value "2" means an "inoperative channel" is detected. A physical module fault, channel fault, terminal block error or software/hardware configuration error can lead to this. It is suggested to either replace the card or more to another channel or observe the behaviour after disconnecting the load.

Resolution
To troubleshoot the card further, the recommendation is to create a new program only with hardware configuration and no program references to the module's Input/Output addresses just to check whether or not it could be software/program configuration issue. Please do the test and check the status of the MOD_FLT respectively and whether or not you see a CH_HEALTH stay at 0.
If there is a CH_HEALTH bit that stays 0, there is likely a physical issue with the module.

For more information, see "Modicon X80 - Discrete Input / Output Modules, User Manual" (Reference: 35012474K0100)
See p371 for CH_HEALTH
See p374 for MOD_FLT

If you log into your PLC, you can find the DDT Variable if you go to the "Variables & FB instances" folder and expand it, then double-click on "Device DDT Variables"
In the Variables tab, you should see a variable named "PLC0_dx_ry_sz_DAI1604", where the x=drop number, y=rack number, z=slot number followed by the Module name. (If the I/O module is on a different EIO bus, the variable will start with "EIO2" or higher)
Expanding this structure variable, you will see MOD_FLT global status byte to all channels and a Health Bit "CH_HEALTH".
 

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