Cutler-Hammer D320 PLC, User Manual

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Appendix C: COM2 UDCP Specification
239
Rung 3:
This rung handles the
Query message. If no
message is currently
active, it starts the process
by creating the Query,
setting the Send Request
bit (F11.0), and starting
a Timeout timer.
CALL
SL=0
F11.0
S
M0.0
S
==
A=K0
B=0
F11.0 F11.4 M0.0
TIM
CH=64
SV=30
M0.0
Rung 4:
This rung handles the
Response Request
message. If the Query
has been successfully sent
and Acknowledged, it starts
the process by creating the
Response Request, then
setting the Send Request
bit (F11.0) and starting a
Timeout timer.
CALL
SL=1
F11.0
S
M0.1
S
==
A=K0
B=1
F11.0 F11.4 M0.1
TIM
CH=65
SV=30
M0.1
TC64 F11.5
M0.0
S
R
INC
D=K1
Rung 5:
This rung checks the 3
second timer started after
the Query message was
sent. If the timer times out,
it increments an error
counter (K1), and restarts
communications.
M0.0