Can I use the PWM output of a PCI-7344 cabled to a UMI to control a servo motor (closed loop)?

[bnadeau]

I need to control both velocity and position of a servo motor and use PWM as the control output to a 3rd party driver board. I want to use the PWM output as the control signal and the encoder for feedback.

[Jochen]

You can use the PCI-7344 to control a PWM drive but not by using the PWM outputs of the board. The PWM outputs are static and can't be used as the outputs of the control loop. Instead of this there is a special kind of firmware available from NI that turns the step and direction outputs into true PWM control outputs. This firmware is still beta but it proofed to work without significant problems for a number of users.
Please contact you local NI-Support by filling out the form on www.ni.com/ask in order to get this special firmware and a description how to use it.

Best regards,

Jochen Klier
Applications Engineering Group Leader
National Instruments Germany GmbH

[bnadeau]

Thank you Jochen. I am currently using the PWM firmware upgrade. Initially, it seemed very promising except the the logic of the direction line was reversed for my drive board. I build a simple inverter circuit and thought that all was well until the direction output stopped updating at all. It outputs a noisy .6 volts regardless of the direction. I have tried rebooting, cycling power, etc., but I can't get it working again. The pwm is fine and the anolog output is fine if I go back to the original firmware. Can you suggest anything? I am now pursuing a circuit to convert the analog control signal to a pwm and direction output, but this is very time consuming. Thanks!