Rockwell Automation 1770-KF2 Data Highway or Highway Plus Interface Module User Manual User Manual

Page 89

Message Packet Formats

Chapter 5

5-10

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:

Reply Format:

TNS

STS

CMD

SRC

DST

FNC

TNS

STS

CMD

SRC

DST

DATA — Max. 243 Bytes

DATA — Max. of 243 Bytes

Diagnostic Read

This command reads up to 244 bytes of data from the PROM or RAM of
the station interface module. You can use it to read the module’s
diagnostic timers and counters. Except for the PLC-5, you must use the
diagnostic status command to obtain the starting address of the diagnostic
counters. The PLC-5 doesn’t require that this address be specified,
though you must include a dummy value in the ADDR field, which the
PLC-5 will ignore.

Command Format:

Reply Format:

TNS

STS

CMD

SRC

DST

FNC

TNS

STS

CMD

SRC

DST

ADDR

DATA — Max. of 244 Bytes

SIZE