I/O Module Test Error

What does E3-18 mean?

A general test error has been reported by an I/O bus module. This indicates a failure during an internal diagnostic test, implying an issue with the module's hardware or firmware functionality. This can lead to unreliable I/O behavior or a complete module failure.

• Internal hardware fault within the I/O module (e.g., faulty ASIC, memory corruption) detected during self-test.
• Corrupted or incompatible firmware on the I/O module preventing successful diagnostic routines.
• Transient undervoltage or power spike on the I/O module's supply (e.g., 24VDC) during diagnostic execution.
• Over-temperature condition within the I/O enclosure causing internal components of the module to become unstable.
• Backplane communication error preventing the I/O module from correctly reporting its diagnostic status to the CPU.

Click steps to track your progress.

1. 1

   1. Retrieve detailed diagnostic messages for the I/O module from the PLC's diagnostic buffer (e.g., Step 7 Diagnostics).

2. 2

   2. Measure the I/O module's power supply voltage (e.g., 24VDC) at its input terminals for stability.

3. 3

   3. Perform a firmware update on the I/O module if a newer, compatible version is available from the manufacturer.

4. 4

   4. Reseat the I/O module firmly in its backplane slot, inspecting the connector for bent pins or debris.

5. 5

   5. Replace the I/O module with a new or known good spare of the same part number.