Rockwell Automation 1775-KA PLC-3 Communication Adapter Module User Manual - Manual (Page 231)

Detailed Flowcharts
Appendix D
DĆ21
Figure D.25
XMSG Subroutine
XMSG
GETBUF
Check Availability
of Receive Buffer
Clear BCC
Accumulator
GETCODE
Get a Code
Link Data
?
Code =
Station No.
?
Buffer
Available
?
Buffer
Overflow
?
Save Byte
in Buffer
GETCODE
Get Next Code
Return An
Ignore Flag (0)
Link Data
A
No
Yes
No
Yes
Yes
Yes
No
No
No
Yes
Output Flag:
•
ACK if Message is OK
•
NAK if Message is in Error
•
0 if Message is to be Ignored
Return
an ACK
GETBUF
Try to Get
Another Buffer
SENDNET
Send Link Data to
Network Layer
Save New Header
Duplicate
Message
?
Compare Message
with HEADER
A
DLE ETX
?
Was
Buffer
Available
?
Did
Buffer
Overflow
?
Message
Too Small
Error
Flag
?
No
Yes
BCC = 0
Return
a NAK
10095–I
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
No