Labview

Its been a while since I worked with LabVIEW but isn't the PID library function supplied with LabVIEW and process control is just via a standard analog output module?

I don't understand what the time proportional digital output is supposed to do but surely the time proportional element can be done within LabVIEW with the output controlling a standard digital output module.

Also, you can edit and modify existing LabVIEW function blocks (like the P, I and D functions) to create a desired custom function.

Can you provide more information?

The control function library is not included in the professional development environment, it is a $2K add on.

Time proportional digital output is simply an on/off binary output that is time proportional, ie. 25% out with 2 second duty cycle would be 0.5 sec on, 1.5 sec off.

Does your verson of LabVIEW allow you to make your own custom library functions to create the control element you require?

If not, you will either need to upgrade LabVIEW or try and implement the function outside of LabVIEW in the real world using hardware like a programmable timer relay (which may not be easy).

Jack, Yes, I was hoping someone had already put one together and might share it to save me the time. Discreat controllers with time proportional outs are common and cheap, I have used them plenty in the past, but that is not my prefered solution for this application. I know that I could upgrade if I wanted to fork over $2K.

A quick internet search might yield one, or a document detailing how to make what you need (there is a fairly large LabVIEW community).