View Full Version : PID control?

March 10th, 2004, 07:10 PM
Is there any way to program a PLC to perform PID type logic without purchasing a module with it built in? :D

Mark Buskell
March 10th, 2004, 07:25 PM
Buy a plc with build in PID loops like Allen-Bradley.

Sleepy Wombat
March 10th, 2004, 07:33 PM
Omrons CPM2A, CQM1H, C200H, CS1, CJ1 all support PID in their instruction set.

In fact the CJ1 and CS1-H even support PID with auto tune....

Another alternative is to program your own..Look into Sliding Mode Control (Search this forum for more details)

March 10th, 2004, 07:44 PM
maybe a FP0 from Matsu****a it have a PID and auto-tune built-in

Tom Jenkins
March 11th, 2004, 11:01 AM

1) Most newer PLCs have some PID loops built in to the CPU, and not into an extra I/O or specialty card. A-B and AutomatinDirect.com and GE and most others now do it this way. Most limit you to one or four or some other specific number of PID loops.

2) PID is just a mathematical equation, widely published, and essentially using only four function math. If you understand the algorithm, you can "roll your own" PID and do the calculations in ladder or whatever.

3) Depending on your application you may not even need PID - there are lots of ways to control a process.