Amplifying the current of ni9264 for controlling a DC motor in both directions:

Question

I want to control a DC motor in both directions by NI9264. The problem is the module can not provide enough current.
It is easy to amplify the current by a "common collector powr transistor" for 1 direction, but how can I make it reversible?
p.s. It does not matter if I use one port with +/- 10v or two different ports for one mottor.
Thank you for your answers in advance.

Answer 1

Navid,
typically DC motors are not driven by a proportional current signal, but by a PWM signal which is provided by an H-bridge circuitry that allows bidirectional moves.
So you either could use an external power drive, that accepts a +/-10 V input signal from the NI 9264 or you could replace this module with an NI 9505, that has a powerful H-bridge circuitry built in in addtion to quadrature encoder inputs, which are typically required for a motion control application, too.
Please note, that the NI 9505 can only be used in a cRIO chassis but not in a cDAQ chassis. In general for a motion control application should be done with a cRIO system and not with a cDAQ system, as you won't be able to run a stable and deterministic control loop with a cDAQ system.
Kind regards,
Jochen Klier
National Instruments