Allen-Bradley 1779-KFMR User Manual page 111

Diagnostic Read
Use this command to read up to 244 bytes of data from the PROM or
RAM of the interface. You can use it to read the interface's diagnostic
timers and counters. Use the diagnostic status command to obtain the
starting address of the diagnostic counters. You can send this command to
any node interface.
Command Format:
Success Reply Format:
Unless otherwise stated, values shown are in hexadecimal, and each block
shown represents one byte.
Diagnostic Status
Use this command to read the diagnostic status block from any node
interface. The reply to this command contains the status information in its
DATA field.
Command Format:
Success Reply Format:
Unless otherwise stated, values shown are in hexadecimal, and each block
shown represents one byte.
Chapter 8