Allen-Bradley 1779-KFMR User Manual page 164

Reply Format:
Read Remote Command
Use this command to determine what remote command is stored at a
remote programmable controller station under a specific remote command
identification (RCID).
Command Format:
If the STS field in the reply header has a value of 00, that indicates a
transaction-completed reply which has message fields for the application
layer.
Success Reply Format:
If the STS field in the reply header has a value other than 00, that
indicates an error reply which has no message fields for the application
layer.
Chapter 10