PID CONTROLLER

[Freddino]

i, it's the first time i write here and i hope somebody give me an answer.I have to implement a PID controllor using mathscript , what i do is to take data with the first daq ass. and pass to the mathscript node and after i move equPID to the second daq to give a voltage to an actuator.The two daq are setted with 100 hz rate and 100 samples to read.When i run the application i have an error:Error -200609 occurred at DAQmx Write (Analog 1D Wfm NChan NSamp).vi:1  Generation cannot be started, because the selected buffer size is too small.Increase the buffer size.Selected Buffer Size: 1Minimum Required Buffer Size: 2.If somebody could tell me where i mistake i'll appreciate.THX

[GrantM]

Hello,

The MathScript Node does not currently implement automatic error handling like other objects in LabVIEW.  This should change in a future release, however.  Until then, you should always wire the error out from the MathScript Node.  There are a few minor errors in the script that are easily correctable if you wire the error out.  Also note that even though LabVIEW has localized versions, the MathScript language itself is not localized.  Consequently, you must use a decimal point as the decimal separator.  This is most likely what you intended on the first line of your script.  What you have typed is not an error in MathScript and would most likely be more difficult to debug.  The line
Tc=0,01;
is interpreted by MathScript as the following two lines
Tc=0
01;
since a comma is a statement separator.

Also, did you mean to acquire an array of data in every iteration of the loop?  Or did you want to acquire data once and then run this test over every data point?  If you mean the latter case, you should move the data acquisition outside of the loop.  National Instruments also sells a PID Toolkit that may make your application easier to design.

Grant M.
Staff Software Engineer | LabVIEW Math & Signal Processing | National Instruments