For Unity CPUs (standard CPUs and Safety CPUs), the following system words that can be referred are from %SW535 to %SW640 for RIO Network Diagnosis.
To detect global communication:
To detect global communication:
1.) %SW535 (RIO error on start-up),
2.) %SW536, %SW537, %SW538 (Communication status on cable A),
2.) %SW536, %SW537, %SW538 (Communication status on cable A),
3.) %SW539, %SW540, %SW541 (Communication status on cable B),
4.) %SW542, %SW543, %SW544 (Global communication status)
To detect errors coming from the drops:
1.) %SW545 to 640 (Status of decentralized stations) for communication error bits:
2.) %SW545 to %SW547 are dedicated to the local station
3.) %SW548 to %SW550 are dedicated to the drop 2
4.) %SW551 to %SW553 are dedicated to the drop 3
5.) %SW553 to %SW556 are dedicated to the drop 4
6.) and so on....