I use Visilogic and Unilogic for teaching.
To be able to demonstrate PID responses using a mA source on the input (simulated process value) and a mA meter on the output, I would (also) like to run the PLC as i PID controller with no process connected.
I first made such a program using the Visilogic (V570) and it worked just fine to remove all auto-tuning and to have only manual configuration of P, I, D parameters. (And the output (CV) could be sat manually as well)
Then I tried to do the same with Unilogic (USP-70-x10) and this seems to be more difficult. It looks like you first have to make an auto-tuning before the PID function will work. (The Status Indicator will show zero or some other value that will prevent the PID controller from running.)
I have found out that if you take the simulated process value from the mA source up and down a few times, I can "fake" a process response and make it run that way, but it is not a really good solution.
Is there any possible way of programming a PID control function without auto-tuning?
If it is impossible it would also be a valid answer. Then I don't need to use more time to find it out, If it can not be done or not 🙂
(I think that the problem is that the PID_Config.Status bit is not so easy to manipulate without making an auto-tuning first, and that's the reason it is difficult to run it in manual mode, without making this auto-tuning first. Hopefully I'm wrong in some way, or there is some workaround to this "problem".)