Allen-Bradley PLC

77 – Communication fault

Communication fault with remote I/O

Details

Communication failure detected with remote I/O rack.

Error typefault
MeaningRemote I/O fault
Typical causesCable disconnected network fault adapter failure
SolutionsCheck communication cable verify network configuration test adapter module
Severityhigh

Catalog references

Vendor Information

Allen-BradleyFault Code 77

Utilities

Troubleshooting Steps

Troubleshooting steps

Check communication cable verify network configuration test adapter module

Other codes

Other Allen-Bradley PLC Codes

16 – Processor fault

Processor fault detected

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38 – I/O module fault

I/O module configuration fault

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20 – Remote I/O fault

Remote I/O communication fault

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21 – Communication timeout

Communication timeout with remote device

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22 – Network fault

Network communication fault

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FAQ

Common questions

Is the remote rack powered?

Ensure remote rack has power and communication adapter is functioning.