simulate analog values in STEP 7

Hello guys,
I'm learning how to design a PID controller in STEP 7. Now my first question is how to check if PID working OK? I want to test it but I know that analog values are treated with PIW (like integer numbers). Is there any way to simulate analog values in STEP 7 (PLCSIM) that would present input to the controller?
Is this even possible?
Thanks

Hi

I too am learning all aspects of S7 and have recently experimented with the PID function.
Ideally you need to get hold of a process calibrator, ie. a 4-20mA or 0-10V source, you would need one in the field during commissioning.
I do not have one at the moment so I have hooked up an analog input device, also I have used an analogue output device with a 0-10V feedback- to feed back into another analogue input channel.

Darren

Pandiani said:

Hello guys,
Now my first question is how to check if PID working OK?

Click to expand...

I use a software simulators simualtes the desired system.

Pandiani said:

Is there any way to simulate analog values in STEP 7 (PLCSIM) that would present input to the controller?
Is this even possible?
Thanks

Click to expand...

I don't know if these functions can be added to PLCSIM. If the PLCSIM can execute normal ladder I don't see why not. One would need to write a FB that has a system gain and time constants or frequency for each desired pole or zero. The input would be the control signal from the PID and the ouput would be the process variable. The process variable would be the feed back to the PID.

I started another thread, in school we learned about system presentation with zeros and poles through transfer function but in practice and in Step 7 everythiong is more complicated. I wonder if it is possible to simulate process output with controller just like in MATLAB

You should be able to get an FB from Siemens that does PID. The simulator will plug in an integer for your analog input and the program will give you an output. If you want to put a curve for your input or an equation based on your output that is a different story. Use an internal register for your simulator instead of the input and write yourself the equation as part of your Step7. I know they might also sell you something that works with nice icons.