RodneyC
Member
Hello all,
I'm new to the forum so I apologize if the info I'm looking for has been covered before. I used the search function to try to find some answers regarding the PID instruction in rslogix 500, for use in an AB SLC5/05 PLC.
What I have is an older system, a Krones vacuum bottle filler which uses a 4-20mA level sensor to detect the level of wine in the filler bowl and adjust a pneumatic valve's position to control the fill level. The valve is operated by the PLC analog 4-20mA output (1746-NO4I output card) via a current to pressure converter, which receives the 4-20 signal and sends a 3-15psi pilot signal to the control valve.
The issue we are having is that the setpoint is being met, and then exceeded by a lot before the PID is sending an output to close the valve fully (4mA = closed). It will also sometimes close the valve, then slightly open it repeatedly for a good minute or so after the setpoint has been exceeded.
I'm trying to learn everything I can about tuning the PID block. What setting change the PID's tracking, or how tightly the output is maintained.
I did test to see that my level sensor is sending a correct signal, and it seems rock steady and accurate.
I've attached the current program in .RSS format (zipped). Any help would be much appreciated!
I'm new to the forum so I apologize if the info I'm looking for has been covered before. I used the search function to try to find some answers regarding the PID instruction in rslogix 500, for use in an AB SLC5/05 PLC.
What I have is an older system, a Krones vacuum bottle filler which uses a 4-20mA level sensor to detect the level of wine in the filler bowl and adjust a pneumatic valve's position to control the fill level. The valve is operated by the PLC analog 4-20mA output (1746-NO4I output card) via a current to pressure converter, which receives the 4-20 signal and sends a 3-15psi pilot signal to the control valve.
The issue we are having is that the setpoint is being met, and then exceeded by a lot before the PID is sending an output to close the valve fully (4mA = closed). It will also sometimes close the valve, then slightly open it repeatedly for a good minute or so after the setpoint has been exceeded.
I'm trying to learn everything I can about tuning the PID block. What setting change the PID's tracking, or how tightly the output is maintained.
I did test to see that my level sensor is sending a correct signal, and it seems rock steady and accurate.
I've attached the current program in .RSS format (zipped). Any help would be much appreciated!