How many instruments can I control with the PID software using LabWindows/CVI?

[Chris Hecker]

I am controlling eight different instruments with labwindows and field point. They each have heaters which need to be controlled with the PID software. I need to know how many different PID loops that labwindows can handle. The pid_config function panel says that there can only be 5 loops, is this correct? Is it possible to add more loops?

[Jeremiah Cox]

Hello Chris,
Yes it is possible to have more than five (5) loops when using the LabWindows/CVI PID Control Toolkit. If you open the pid.c source code, you will find an enumeration near the top "#define NLOOPS 5". Change the number after NLOOPS to the maximum number of loops that you desire to control. This is explained further on page 1-9 of the "LabWindows/CVI PID Control Toolkit Reference Manual", available online at "http://www.ni.com/manuals".

Jeremiah Cox
Applications Engineer
National Instruments
http://www.ni.com/ask