Pause the counter output in DAQmx

[ycw7]

Hi~

I used two counters output on PCI-6602 card in LV7.1 to generate a PWM to control the velocity of two motors that control the position of mechanism.(Encoder was set on the motor.)
When I set the same duty cycle in two counters, the position of two mechanisms were different(Two mechanisms were the same),that means one velocity of motor was fast, the other was slow.
May I pause the counter output of the fast motor to wait the slow motor??

[Kevin_Price]

Assuming you're using DAQmx, you can set up a Pause Trigger for each of the counters.  (A similar function can be done in traditional NI-DAQ too).  You could, for example, configure 2 different digital bits to be used to pause the 2 PWM counters independently.  The way 'Pause Triggering' works is that the counter's pulsetrain only goes to the output pin when the pause trigger signal is in the correct logic state.  This can be set to be low or high by programming. 

You may also want to characterize the speed difference of your actuators, and give them correspondingly proportional PWM duty cycles.  That would do a better job of keeping them in sync throughout the motion.

A feedback signal would give you even better options for control.

-Kevin P.

[ycw7]

Thanks for your comments, Kevin
I'll try it~~