ElecSparky (Customer) asked a question.
P1000 with P1-04PWM.
I want to replace a Solo temperature controllers(s) with a P1-540, P1-04PWM card. Need to use PID with pulse on pulse off time. Any ideas to help with this or a bit of example code to help with that.
Take a look at help topic P167 PID instruction at the bottom under time-proportioning control.
I've done it multiple times with P2K and P1K CPUs.
What type of temp sensor are you using for feedback? Thermocouple or RTD? There are P1K and P2K input modules specific to the sensor type. I'd use those.
In my applications, I was replacing Nordson melters, so I was handling the heating of the tank, hoses, and applicator guns.
I used P and I only.
The P & I settings were specific to their type: tank, hose, and gun. Meaning the P & I for the tank was different from the P & I for a hose or the P & I for the applicator gun.
I used the code from the help topic, but their timer settings were too large, and temps would go over at startup. I made each timer have a .001 time base and a preset value no higher than 1 second so the temperatures remained stable during the run and did not shoot over the set point at startup.
Furthermore, I did use self-tuning of the PIDs, but I did not start self-tuning until, as I remember it, the zone was 10 degrees under the set point.
Hi Todd.
Thanks for the info. appreciate it.
I am using k thermocouple. Will try the example code as per your recommendation and flirt with the timer base resolution. Am I using the correct card (P1-04PWM) for this?
No.
P1-04THM or P1-04THMS.
https://www.automationdirect.com/adc/shopping/catalog/programmable_controllers/productivity1000_plcs_(stackable_micro)/analog_i-z-o#Analog_Input_Signal_Type_ms=%22Thermocouple%22&start=0
Sorry, should have been more specific.
I have that module for the sensors. I meant for pulsing the SSR.
I use the P1-08TD2 output module, and it powers Gefran SSRs.
For my application, 15A rated SSRs were fine;
https://www.automationdirect.com/adc/shopping/catalog/relays_-z-_timers/solid_state_relays/grsh-15-48-d-0-0
Since SSRs for heating purposes are usually based on a 1 second time period, with the % on and off of that 1 second done by the PID calculation, a PWM module is not the best for this use case. PWM is technically what you are doing, with modifying the width of the on period as you get closer to your temperature set point. However the PWM module is really more for higher speed applications where your pulses are many times per second, instead of 1 pulse per second. So a standard output module is better suited to heater output points to a SSR.
Yes, that makes sense. Thanks for the input. I do also have the P1-08TD2 output module which Todd suggested.
I have code in place and somewhat tested. Looks good so far.
Cheers.