Temperature control for simple experiment

[DAQNewby]

I am pretty new to LabVIEW and DAQ, and had a question for you guys.

I am trying to control a temperature in my experiment via computer.  I have a TEC (may be expanded to two later), and a thermocouple taking temperature measurements.  I want to be able to input a temperature curve, and have the temperature follow that curve to heat and cool the sample.

Questions:
Does anybody know of a temperature controlling device that will do this?  I have tried Omega and several others, it seems all of the PID controllers work by rapidly switching on and off the current to the heating element, which I have been told is not good for TEC's.  It would need to take some temperature curve (or close approximation of) and execute it.

If not, I could do this via DAQ (I think).  Anybody know the cheapest signal conditioning for a thermocouple (1 channel)?  I already have a USB-6008, but I need to amplify the thermocouple signal, compensate for coldpoint error, and filter the noise before I can read with that.

After that I need some way to drive a bi-polar current supply, so I can heat and cool with the TEC, with the 0-5V output on the DAQ.

Any suggestions are welcome.

Thanks,
Steve

[Process_Systems]

What you are looking for is a  temperature controller with analog output (probably 4-20 ma.), and a ramp-soak control capability. There are many out there, and some of the Omega ones have these capabilities. Just look carefully at the options. Many of the Omega controllers are made by Neuport or Fuji. If you can't find it on the Omega site, go to the Neuport Instruments, or Fuji Instruments sites. You can do it with Labview, but as you said, you do not have a signal conditioning module. If you choose to go this route, try the 5B series signal conditioning modules. They are about the cheapest single channel solution. You will also need an output signal conditioner for the 4-20 ma analog output to match your heating device.

Good luck

Dave

[DAQNewby]

I was told by someone I'm working with that these are not a good option for TEC's.  Those all work by pulsing power to a relay, which will in turn send "amplified" pulses to my heater.  I was told that these pulses don't work well with TEC's.  Can anyone confirm this?


Message Edited by DAQNewby on 07-03-2008 08:53 AM