Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 209)

Appendix
C
CĆ1
Diagnostic Counter Block
At this
byte offset: This counter is stored:
1. Bad CRC on acknowledgement [2] (Local error A')
2. No acknowledgment before timeout occurred (Local error B")
3. Contention (while master, detected message transmission by
another station)
4. Acknowledgment contained an error (Local error "C")
5. Local errors (Sum of A, B, and C above)
6. Waits (no receive buffer space at destination station)
7. Timed out (master failed)
8. False polls (failure to transfer)
9. Received acknowledgment when not master
10. Message size too small (less than 5 bytes)
11 Incorrect DST, or SRC = DST
12. Memory not available for receive buffer
13. Received message has bad CRC value [2]
14. Message too long
15. Message arrived when no buffer space left
16. Retransmissions of previously received message
17. Aborts (result of line noise)
18, 19. Messages successfully transmitted
20, 21. Messages successfully received
22, 23. Command messages sent
24, 25. Reply messages received
26, 27. Command messages received
28, 29. Reply messages sent
NOTES:
[1] The address of the first byte of the counter block can be determined by using the diagnostic
status command. Addresses of the other bytes listed here can be derived by adding the
appropriate number of bytes to the staring address of the counter block.
[2] An acknowledgment is part of the data highway protocol.
Data Highway Port Counters