There has been quite a lot about PID programming & simulation recently & I thought some people might like this idea, it is a bit Heath Robinson but works quite well, recently an old colleague of mine contacted me about some PID code, however, I only ever did a PI loop, simulating is difficult without true analogues and a real world equipment and of course expensive. I knew my original PI control worked well but my colleague needed D control as well, he tried just PI using a number of methods (my version plus a stand alone controller), however, it proved he needed the D component the PLC is quite old and has no function for PID. I modified my original but having no Analogues on any of my old PLC equipment was a problem and a a 400-600 hundred pounds to purchase them was out of the question.
I built this using a cheap one with built in analogues, it cost about £40.00 I would not use this in a real industrial system but for testing it's fine, using a transistor to convert the 0-10v from the PLC analogue output to drive a small lamp to use as the energy source, a PT100 connected to a 0-10v head converter provided the feedback.
This worked a treat and I was able to test the PID in a real world with a cheap PLC & other components I had lying about.
The PLC is not bad for the price but there are some things that do not work, the unit is 8kb and under normal circumstances using the IDE you could upload the parameters from the PLC, however, this unit will not allow this and as the default new project is set at 16kb you have to configure it , also some of the later features of the functions do not work, but as the IDE has both the older functions as well as the newer ones it's fine.
It's easy to simulate either a quick response as well as a slow one just by position & possibly enclosing the bulb & sensor in a small box.
I built this using a cheap one with built in analogues, it cost about £40.00 I would not use this in a real industrial system but for testing it's fine, using a transistor to convert the 0-10v from the PLC analogue output to drive a small lamp to use as the energy source, a PT100 connected to a 0-10v head converter provided the feedback.
This worked a treat and I was able to test the PID in a real world with a cheap PLC & other components I had lying about.
The PLC is not bad for the price but there are some things that do not work, the unit is 8kb and under normal circumstances using the IDE you could upload the parameters from the PLC, however, this unit will not allow this and as the default new project is set at 16kb you have to configure it , also some of the later features of the functions do not work, but as the IDE has both the older functions as well as the newer ones it's fine.
It's easy to simulate either a quick response as well as a slow one just by position & possibly enclosing the bulb & sensor in a small box.
