The error LED is on and the history contains the message XOB 20 / 25 missing

FAQ #100690

 

Problem
Obviously XOB 20/25 are called and they are not programmed. The PCD has detected a rising edge on INB1/INB2.

Reason
If the interrupt inputs are used XOB20/25 has to be programmed otherwise this will generate an error. If the interrupt inputs are not used and there is a history entry anyway it can be that the PCD detects a rising edge do to disturbances.

Solution
If the interrupt inputs are used, programm the XOB 20 /25.
If the interrupt inputs are not used, connect the INB1 and INB2 to the GND to avoid disturbances