The first occurrence of read and write errors are shown along with the map number that was being processed when the error occurred. Check the reset box and click update to clear it and possibly show the next error if there are more than one active error conditions.

A total count of all errors is also shown. This total is the sum of errors for all maps for this device or unit #. Check the reset box and click update to reset the counts. Click Update to view the most recent data values.

Error code indications of A/B indicate the following errors with the first number:
1 = n/a for RTU (Transaction ID out of sync)
2 = Exception code returned by remote device
3 = Function code mismatch (bad packet)
4 = Inusfficient data (bad packet)
5 = No response from remote device, timed out
6 = CRC error in received packet

When A is code 2 indicating an exception code was returned, B indicates the exception as follows:
1 = Illegal function code
2 = Illegal data address (the requested register does not exist in the device)
3 = Illegal data value