How to solve communication errors in PLC

In Allen Bradley RS LOGIX 5000 PLC
I/O not responding alarm

It means any communication errors

What is the error meaning “No reply from PLC within Timeout period” ?

This happens if a valid reply has not been received from the PLC within the specified timeout period and the communication packet was retried the defined number of times.


  • Check the load on the PLC and network. The hardware and communication medium might be too busy to handle further communications. If this is the problem, you can increase the Transmission Speed, increase the Receive Timeout, or edit the project to use more consecutive addresses.
  • Check the connections
  • Check the cable
  • Check the cable path for any magnetic interference or induction voltages
  • Check if the PLC device drivers on both the PLC and runtime match
  • Check if PLC hardware device is damaged
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