can anyone help with a PID control vi

[paulmeaney]

Hi
I am doing a project at the moment and I need to build a temperature chamber. I am using LV 7.1 and I have 4 thermistors being fedback to a daq device. I also have two heaters as part of the chamber but i want to get the thermistors readings and pid control the output to the heaters. I have the program written to get the thermistors readings and average them but im having trouble trying to think how i can pid control the heaters so i am looking for a pid vi. If anyone can help it would be great. Thanks....

[tst]

NI sells a control toolkit for LV which includes PID control. You can look for it on this site.
If you want to write this yourself, you should start with an uninitialized shift register. A USR allows you to keep data from the last time you ran the VI. There is an example of using a USR in the LV Example Finder and you can probably some more information about it in this site. You will also need to measure the time between runs and then probably calculate the derivative between each 2 runs to see how fast you're approaching your setpoint.
I hope this helps, as a start.

[Brian_Beal]

There is a Simple PID example that ships with Labview. This may be good enough for what you want to do.