CPU Bus Unit Data Exchange Error

What does A402.07 mean?

This fault indicates an error during data exchange between the CPU Unit and a CPU Bus Unit. When this error occurs, the CPU Bus Unit Error Flag (A402.07) is turned ON, and the bit in A417 corresponding to the unit number of the Unit where the error occurred is turned ON. The CPU Unit will continue operating, and the ERR/ALM indicator on the front of the CPU Unit will flash.

• Communication failure during data exchange with a CPU Bus Unit (unit numbers 0-F).
• Physical connection issue with the CPU Bus Unit.
• Faulty CPU Bus Unit.

Click steps to track your progress.

1. 1

   Identify the faulty CPU Bus Unit by checking the status of bits A417.00 to A417.15.

2. 2

   Inspect the physical connection and bus cables of the identified CPU Bus Unit.

3. 3

   Verify the power supply to the CPU Bus Unit.

4. 4

   Clear the error flag (A402.07) after troubleshooting.