Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 232)

Detailed Flowcharts
Appendix D
DĆ22
Figure D.26
GETCODE Subroutine
GETCODE
GETRAW
Get Byte From UART
DLE
?
GETRAW
Get Byte From UART
DLE
?
No
Yes
BCC
Add Data Byte
to BCC
Return Byte
and Data Flag
Save ACK or
NAK in RESP
WAKEUP
Resume XMIT
if Sleeping
at WTRESP
ACK or NAK
?
Yes
No
No
Yes
No
Yes
ETX
?
Return Byte
and Control Flag
BCC
Include ETX
GETRAW
Get Low Byte of
BCC
BCC
Include in Check
GETRAW
Get High Byte of
CRC
BCC
Include in Check
Return EXT
and Control Flag
10096–I
Output:
•
BYTE –– What Was Received
•
Control/Data Flag –– Set if BYTE is
a control character which was
preceded by a DLE
NOTE: CRC Should Now Equal Zero