Omron C200HW-CORT21 Operation Manual page 38

Control and Status area
36
IR n+3.15 New error(s) in error log
The C200HW-CORT21 has an error log for errors that occurred
due to IOWR / IORD message communication. If new errors
have occurred since the last read action to the error log, IR
n+3.15 is set.
0: No new error(s) in the error log since the last read action to
the error log.
1: New error(s) have occurred since the last time the error log
was read.
See section 4-3 for more details about the error log.
Section 3-2