Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 187)

Message Formats
Appendix A
AĆ25
Diagnostic Counters Reset
Use this command to reset to zero all the diagnostic timers and counters in
the station interface module. The diagnostic status command gives the
starting address for this block of counters and timers.
Command Format:
FNC DLE SRC STX DST C
06
S TNS
MD TS TNS DLE ETX BCC
07
DATA
Reply Format:
DLE SRC STX DST C
46
S TNS
MD TS TNS DLE ETX BCC
Diagnostic Loop
You can use this command to check the integrity of transmissions over the
communication link. The command message transmits up to 243 bytes of
data to a station interface module. The receiving module should reply to
this command by transmitting the same data back to the originating
station.
Command Format:
DLE C S TNS MD TS TNS STX DLE ETX BCC DATA - Max of 243 bytes DST SRC
06
FNC
00
Reply Format:
DLE C S TNS MD TS TNS STX DLE ETX BCC DATA - Max of 244 bytes DST SRC
46