ControlMaster CM10, CM30 and CM50
Universal process controllers,
1
/
8
,
1
/
4
and
1
/
2
DIN
8 Templates and Functionality
104
IM/CM/S–EN Rev. R
8.2.2 Analog Backup Station (Low Signal Selection / Digital Signal Selection)
This template provides a back up for a master controller (system). In normal operating mode, the ControlMaster operates in
Remote Control Mode. In this mode the output of the ControlMaster follows the Master controller's output. If a fault is detected
in the Master system, either by a low signal on the Master output or by a digital input, the ControlMaster switches into Local
Control Mode and the process is controlled by the PID output of the ControlMaster.
The PID algorithm continuously tracks the Master Controller output value to ensure a bumpless transfer from remote to local
operation. Once the Master Controller output is restored or the digital Input returns to its normal state the ControlMaster
switches back to Remote Control Mode and continues to track the master Controller.
(See Fig. 8.4, page 105 for details of parallel connection).
Fig. 8.3 Analog Backup Station (Low Signal Selection / Digital Signal Selection) Template
AIN 1
AIN 2
1
Low Signal Selection
2
Digital Signal Selection
1
2
Alarm 1
Manual Output
AO1
PV
Loop 1
PID Control
L/R
A/M
SP
PID
O/P
Local Set
Point
LSPT1
LSPT2
LSPT3
LSPT4
DIN 1
Master Output