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2 OPERATOR LEVEL…
2.4 Analog Backup (Templates 5 and 6)
Fig. 2.4 Analog Backup Station
LSPt
I/P1
di1
Local Set Point
PV
Process Variable
PID
Control Loop
Local/
Remote
Select
•1
•1 Template 5 Only
•2 Template 6 Only
Master Output
Digital Select
ao1
Manual Output
Low Signal Select
(Alarm 1)
L
LR
Analog Output
I/P2
•2
CSPt
Profile Set Point
Note. Refer also to Appendix A2.1 – Series and Parallel Operation.
The analog backup station provides a backup for a master controller. In normal operation (remote
control mode selected) the COMMANDER 350’s current output follows the master controller’s output
value. A fault in the master system can be identified either by detecting a low signal on the master
output (template 5) or via a digital signal (template 6). When a fault is detected the COMMANDER
350 switches into local control mode and the process is controlled by the PID output of the
COMMANDER 350. The COMMANDER 350 PID algorithm tracks the master output value
continuously in order to ensure bumpless transfer from remote to local mode operation. When the
master output is restored or the digital input returns to its inactive state, the COMMANDER 350
switches back to remote control mode.
Note. The Alarm A1 Trip value must be set when using template 5.
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