Help Requested For Loop Programming

[Kidd 0]

Hi, all. I've got an issue with setting up a PID on an Omron controller and I was wondering if anyone could give me a hand? Preface: I've been programming with my company for the past five years. We have one system with an Omron controller, the rest are AB PLC5, 500, and ControlLogix, so my Omron understanding is very basic. I've done basic ladder logic changes with the Omron, but this is the first time I've been asked to work on a PID. The problem I have is, this system isn't using any PID right now, so I have nothing to look at as an example, and I've read the applicable manuals, but I'm not getting anything. What I have a system cooking under a vacuum. The Non-Con Blower is creating a vacuum in the cooker. The operator enters the requested pressure (usually -2.5 but the range is -10 to +10), and the Blower should speed up/slow down to maintain that speed. Here are the key components to this system: Pressure Input - Honeywell Pressure Transmitter, -10 to +10psia. This goes back to the PLC on a 4-20mA signal, which goes to a C200H-AD003 (Rack 0, Unit C, Slot 2, point 5). This is assigned to Word/Bit 2126, WR Area D645. The Non-Con Fan is on an Altivar VSD, output 0 - 100% (0-60hz). This is coming from the PLC on a 4-20mA signal, which comes from C200-DA004 (Rack 0, Unit D, Slot 3, point 6). This is assigned to Word/Bit 2137, WR Area D27. Ideally, the system should be set up like so: User enters the requested SP on Wonderware (-10 to +10psia). The PLC compares this number to the number being read from the PV, and outputs the difference to the VSD. How would I go about making this happen? Thanks for anything in advance!

[M1923 0]

What kind of omron PLC? It should have a PID instruction as many PLC do.

[Kidd 0]

It's a CS1G-H.

[gtsuport 61]

Couple of things I need to clarify. When you say "point 5" on the C200H-AD003, is that input 5 on the module, or do you mean something different. Current Input 5 would be wired to A8 and A9 on the module terminal strip, with a jumper between A8 and A7. And the input address would be 2125. Also, what addresses do you have in the PID instruction? There are three sections to address: S (Source), C (Control word) and D (Destination). Please be very careful, the Control word is the first of 38 consecutive memory locations, make sure you are not manipulating any of this area with a different part of your program. You may want to track down a copy of the W325 manual for your analog modules and the W339 and W340 manuals for the CS1. Also, what version of CX-Programmer are you using? Hope this will help. Edited 29 Aug 2013 by gtsuport

[Kidd 0]

Sorry I haven't responded yet, I've been in a different state the past week. I will be able to update with more relevant answers tomorrow. Thanks for helping with this. I will have to look into that. I think I've got it being input address 2126, but I'm off on this. I've got a copy of the W325 manual and the manuals for the CS1, I'll give them a read through tomorrow before responding, so I use the correct terminology.