Selecting Process Controller

[Fly5abiGuy]

Hi,

I'm in need of some help selecting a process controller for a small process station. This is my first real "control system" design since I graduated school.

Basically, the controller will process information to/from 2 valves, 2 flow transmitters, and will also have some sort of flow indicator. The distance between the process station and the control room is 500m, so I'm not sure if I should go with remote I/O or not, (as always, cost is a factor).

The controller should be able to perform basic math functions (square root, add/subtract/multiply), and have (2) 4-20mA inputs and outputs.

I will continue googling and making phone calls, but any and all help will be (very) greatly appreciated.

 

[djs]

Check out Automation Direct:

http://www.AutomationDirect.com

If proce is the driving factor they generally have the best.

 

[Fly5abiGuy]

I have been checking them out for the past couple days. My qoute is due tomorrow so I'll have to decide on something by then. Prices at Automation Direct are reasonable, not a whole lot has met the requirements without going overboard.

 

[AGomaa]

Basically you are talking about two PID loops, with no logic involved.
I prefer to go directly to sand alone controller, this is far easy to install and I think will be cheaper, you may check OMIGA as one of the cheap sources for controllers,
You can find many vendors who provide one or two loops controllers.
Flow transmitter (now) came with sqrt as built in function so I think you do not need it in the controller.
Check the distance for max allowable loop resistance. For both your IN and OUT signals.
Calculate the wire resistance and select the proper wire size.
Use shielded cable to minimize the interference.
Run your cable away of power cables.
Good luck