pm dc motor control using pxi1 1010 systems

[rachadeepak]

sir ,

I have two PM  dc motors for a closed loop speed control application . one rated 24 v and 12 v , with tacho generators attached to them  giving an output of 6 v /1000 rpm  and running at 1600 and 1200 rpm respectively on no load , i am using the pxi 1010 system in which the ni pxi 6221 multi function daq card to read the tachogenerator outputs using the DAQ mx  . The problem with the VI attached to the mail is that . i am able to read only one of the tacho output reading . i.e either channel 0 or channel 1 at a instant instead of both the readings , though both the machines are running . the two loops are not running simultanoeusly . i made use of a motor driver circuit for this application using A 3949 IC , where the digital signals in the VI are the signals to this driver circuit . please suggest or make the changes in the ac15.vi . also please help in tuning this system seperately , can i use the pid auto tuning vi  as a controller for this application . how to decide on the values of parameters of the pid for this application

[davidpcl]

From what I can see it looks like you want to configure both of your input channels as a single task i.e. if you wire a comma delimited string list of channels to the Physical Channels input of the Daqmx create channel.vi. What this means is that any reads you do on these two channels will now be perfectly synced by the daq card, so all you have to worry about is syncing your software.

I've attached a .vi to show what I mean.

D Clark