Small process for testing PID tuning software

Hi all,

I'm interested in setting up a small process in my office to test some PID tuning software. I want to make sure I've got it all down-pat before I take it out to the field.

Any suggestions on something simple and practical? A heating loop perhaps? Maybe illumination control? It should be small and relatively inexpensive.

I've been thinking along the lines of using a simple heating electrical element connected to the output of a micro VSD for analog output control. I'll talk to it using Modbus. The PV will be a TC or RTD, whatever I've got handy.

Thanks,

Yosi

Any loop needs an input sensor, a final control element and some means of changing the loop 'capacity'. Temperature uses electricity, less messy than flow or level and a meter of thermocouple wire can be had without a lot of cost or effort.

Do you have a thermcouple or mV AI input card?

I'd scrounge an old toaster and use it to heat pieces of scrap metal.

Or a cartridge heater and a T/C can easily be stuck in different media to change the capacity; water in small cup, oil in a bucket.

I've got a TC module lying around, add to that Modbus to a micro-drive. Connect the output of that to one of those coffee heaters. Changing the output frequency of the drive should give me control over the heating element.

i suggest to buy process meter.

(8{)} ( .) said:

I've got a TC module lying around, add to that Modbus to a micro-drive. Connect the output of that to one of those coffee heaters. Changing the output frequency of the drive should give me control over the heating element.

Click to expand...

Sounds like a plan to me.

What is the process you are going to tune in the field? This is IMPORTANT! What many don't realize is that tuning software is often only able to tune certain types of systems. If it wasn't designed to tune the system you are trying to tune you are out of luck.

The MOST important item is whether the system is an integrating ( type 1 ) or non-integrating system ( type 0 ). Non-integrating system are those where the process variable will return to some ambient state if the control signal is taken away. Temperature and speed control systems are non-integrating. Position control and level control are integrating systems.

BTW, if you are going to tune a type 0 FOPDT or SOPDT system then look at this:
http://deltamotion.com/peter/Scilab/AutoTune/

It works. Someone added a front end to my Scilab program.