Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 134)

Binary Command Language
Appendix A
A-6
Table A.B
Fault Code
HEX fault code value Description
00 No fault
01 Checksum error
02 Format fault - missing ETX
03 Format fault - other
04 Input buffer overflow
05 No input buffer available
06 Previous buffer still in progress
07 Command block sequence count error
08 Receiver error
FF Unknown protocol failure
Block Sequence Counts
Both the master and scanner maintain a command block sequence count
and a response block sequence count. These counters are separate entities
and do not necessarily agree. The scanner:
checks the command block sequence when received
compares it to its own version of the command block sequence count
increments the command block sequence count when a valid command
is received.
The response block sequence count is incremented and sent out by the
scanner. The master checks the response block sequence count when
received and compares it to its own version of the response block
sequence count.