Rockwell Automation 1775-S5_SR5,D17756.5.5 User Manual PLC-3 FAMILY I/0 - Manual (Page 141)

Binary Command Language
Appendix A
A-13
Figure A.1
BCL Protocol Diagram
1
2
External Device PLCĆ3 External Device PLCĆ3 External Device PLCĆ3 External Device
To Sheet 2
From Sheet 2
ACK
Break
Character
Timeout
Invalid
Response
NAK
Terminate
Communication
Terminate
Communication
Channel
Timeout
Break
Terminate
Communication
CCR or
Command Block
No Response
Timeout CCR CCR
Response
Yes
Character
Timeout
Break
Fault Code
00 Hex
05 Hex
Other
Terminate
Communication
3rd
Try?
1
2
External Device PLCĆ3 External Device PLCĆ3 External Device PLCĆ3 External Device
To Sheet 1
From Sheet 1
ACK
Break
Shift
Character
Invalid
Terminate
Communication
Response Block
No
Yes
Channel
Timeout
Break
Character
Timeout
3rd
Try?
or CCR Response
Out
Timeout
Response
NAK Terminate
Communication
Are
There
More Blocks
in the
Response
?
Shift
In
Shift
In
Break
Other
No
Yes
3rd
Try?
Terminate
Communication
Terminate
Communication
Terminate
Communication
CCR
PLCĆ3
Yes
No
CCR
Response
Fault Code
00 Hex
05 Hex
Other
Character
Timeout
Break Terminate
Communication
Will Not Occur During
Multiple Block Responses