pid

[MartinMcD]

Hello,

I currently have a sub-vi sitting in a while loop which is the proportional controller for my system.  This works fine however I wish to change to a PID controller, so I need knowledge of the previous error value to compute my I&D terms.  I don't have the control toolbox.  Of course I could easily do this by feeding the error term into and out of the subvi and using a feedback tunnel.  However, I was wondering if there is a way of accessing the previous iteration's value within the sub vi so it looks neater than having to pass data in and out.

Can anybody help please or am I just being daft?

Thanks,

Martin

[JB]

Are you familiar with shift registers ?

Message Edité par JB le 03-03-2008 02:13 PM