How do I CONTROL temperature with LABVIEW

[JHD0210]

I have a heating device and I need to use it to heat control the temperature of a liquid. It sounds like I need some sort of temperature controller that labview would interact with. How do I find a temperature controller which will work with Labview?

[Dr._Imad]

<<"I need to use it to heat control the temperature of a liquid>>"

You may need a heater (ON/OFF) to warm the liquid, and/or water valve to cool it down. The water valve could be a simple ON/OFF mechansim or a proportional valve control.

ON/OFF mechansim rquires the activation of a RELAY. With LabVIEW and a DAQ card that has Digital Out's, you can energize the RELAY.
If you choose to use proportional control (for the water valve), you need an analog output to control the valve (0 to 5/10V, or 4 -- 20 mA), and then someform of PID control which you can easily implement with LV

Hope this helps

[John Rich]

Temperature control with LabVIEW is relatively easy. You need a temperature sensor (a thermocouple, e.g.) and a data acquisition (DAQ) card to read the sensor output. You also need a relay and a digital Input/Output (DIO) port on the DAQ card. The relay will be used to turn power on and off to the heater. In order to control the temperature you turn the heater on and heat the liquid until the temperature is above the setpoint. You then switch the heater off until the temperature drops back below a lower threshold (this can be very close to the setpoint). You can get more complicated, depending on the level of control that you need.

There is an example using a cFP device at the following URL:

http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3D9CF56A4E034080020E74861

You may also find a lot of other valuable information by doing a search of the NI web site.

Message Edited by John Rich on 04-07-2005 01:29 PM

[Eddy01]

i have a project where i have to control the temperature of a soldering iron but the temperature control vi can't find the files it need to open (the FP Write.vi and all that) can you help me please

[smercurio_fc]

The example in the link uses FieldPoint, which is where FP Write comes from. Unless you are using FieldPoint modules, the example won't do you much good.

I suggest you create a new thread with your question, providing details in terms of what hardware you have, such as the soldering iron, and what DAQ hardware you have.

[Eddy01]

we're using a power supply and a multimeter we don't have the PID or the field point so we can't figure it out 

[Henrik_Volkers]

It would be helpful if you tell us what type of powersupply and how do you control it.

Same for the multimeter, with the addition that the type of temperature sensor is also of interest.

If you want to use the heating element as a sensor, you need to know actual current and the voltage at your powersupply/iron ....

[Eddy01]

we are using the agilent 34401A as the multimeter and E3631A for the power supply i don't know the thermostat but we use a formula to convert voltage to temperature (if you have another formula i wouldn't mind trying it)

[smercurio_fc]

That still only tells half the story. What's your heating element? How is the power supply used to control heat? The formula for converting voltage to temperature is completely dependent on the type of temperature sensor that you use. The documentation for the device you're using will tell you this information. You said you're using a thermostat. These devices usually regulate temperature on their own. For instance, homes have thermostats. They're self-contained. Neither LabVIEW nor any other programming language will help you with this unless you have the hardware set up to be able to perform the operation you want to do.

[GregFreeman]

In college I had a temperature controller that was just RS232 and I used standard serial commands to communicate with it. What you need may depend on your application, but I basically just gave it a setpoint and the PID controller took care of the rest (if I remember right). It really depends on your application.

Lol, I answered the OP which is 6 years old.