Hi there,
I have a small heating system with a micro 830 PLC to assist with the learning process of automation and PLC's etc. The system is a small brewery where a volume of water must be heated to a setpoint and then held.
I have written a program in connected components workbench CCW using the standard IPID controller function block.
The problem I'm having is that when tuning the control loop, the controller output value (CV) is abnormally high and does not begin to decrease until PV=SP which causes significant overshoot. A PID controller should start reducing the CV as SP is approached however the CCW controller does not seem to. If I disconnect the feedback loop in the function block then the controller behaves more predictably as in the CV = gain x (PV-SP) however with the feedback disconnected only the gain value can be used which does not allow SP to be achieved(required Ti).
Looking through the documentation in CCW it seems that there is a minimum value of 0.0001 for the Ti variable which even when set to 0 seems to still load up 0.0001.
Has anyone had a similar issue using PID control in CCW?
Has anyone written their own PID controller for use in CCW that actually works and could share?
Cheers,
I have a small heating system with a micro 830 PLC to assist with the learning process of automation and PLC's etc. The system is a small brewery where a volume of water must be heated to a setpoint and then held.
I have written a program in connected components workbench CCW using the standard IPID controller function block.
The problem I'm having is that when tuning the control loop, the controller output value (CV) is abnormally high and does not begin to decrease until PV=SP which causes significant overshoot. A PID controller should start reducing the CV as SP is approached however the CCW controller does not seem to. If I disconnect the feedback loop in the function block then the controller behaves more predictably as in the CV = gain x (PV-SP) however with the feedback disconnected only the gain value can be used which does not allow SP to be achieved(required Ti).
Looking through the documentation in CCW it seems that there is a minimum value of 0.0001 for the Ti variable which even when set to 0 seems to still load up 0.0001.
Has anyone had a similar issue using PID control in CCW?
Has anyone written their own PID controller for use in CCW that actually works and could share?
Cheers,