|Back-up Control with KS 94
The KS 94 does not have an input for YHM (hard manual). Nevertheless a little trick allows the realisation of a
back-up control loop. In this special case the controller outputs must control a motorized valve, accordingly we need
3-point stepping outputs.
The output of the master controller, e.g. realized as a PLC function, is connected as a 4...20mA signal to
the OVC+ input of the KS 94 controller. As long as this signal is ok, the motor position will follow. If the master
fails, the currant is 0 and the KS 94 takes over the control loop in complete automatic mode. Via digital
input di10 the OVC function can be switched off.
1.1 Option (gray lines)
If the KS 94 should use the last process value as setpoint, the KS 94 must be switched to external setpoint
during back-up mode and the x-tracking function must be activated.
2 INSTRUMENT VERSION
KS 94/TPS with option C (The TPS voltage is used to supply the di1/di2 input)
3.1.1 Possible Controller Types
2-Point, 3-Point, continuous, continuous controller with positioner
3.1.2 Additional Configuration
Setpoint/cascade control; process value tracking (option)
OVC+ (INP4) as 4..20mA sensor fail: xFail=100% and OUT4 switches over y/Y2 via di1.
Copyright ę 2001 PMA Proze▀- und Maschinen-Automation