Sending Pulse Train to Stepper Motor

[Jess_I]

Hi all,

I am trying to drive a stepper motor by sending a pulse train from Labview. I'm currently using NI-9485, as we had a couple open channels that I could use to prove it out, but I don't think this will be the best option as a more permanent solution. I'm trying to control an Oriental Motor PKP stepper motor via its CVD223FBR-K driver and cannot get the I/O signal to send from the NI-9485. The other channels on this card are controlling DC motors (driver BLH2D30-K), and when I use the same code to them (image below), I get the expected 5V pulse output and motor movement, so I don't think the issue is on the Labview code end. Even connecting to the same channels that I'm able to use to send the pulses to the DC motors do not have a signal when I probe them after disconnecting the DC motor drivers (both with and without the stepper motor driver connected). Any ideas here? Happy to provide more details if needed.

As I will ultimately need to be sending pulses faster than I think the NI-9485 will allow, and only need to be sending a 5V signal, I was thinking that NI-9472 would be the better choice. Does this make sense?

I am very new to this and appreciate any help you can offer!

Thanks!

[ZYOng]

NI-9485 is a relay output module and only switches external voltage.

If you only a 5VTTL signal, NI-9401 is the best as it can access the onboard counter of cDAQ and send pulses up to 10MHz.

[Jess_I]

Thank you! You were indeed correct that I was not providing the external voltage that was needed. The other channels must be getting it from those DC motor drivers in a way that the stepper motor driver cannot provide. I've fixed the wiring and it is now getting the pulse signal that I'm sending from Labview. 

However, the motor is still not working as expected. It seems to be both missing pulses and switches its direction of movement randomly. I'm sending a signal that should be slow enough for the relay to handle, and all of the pulses are making it to the motor driver, so I think my problem is now on the motor/driver side rather than the digital I/O side, but if anyone has any ideas on this, I'd still appreciate them.

In terms of the right module to use for this going forward, I agree that the NI-9401 would do what we need it to do. As we will need 6 DO channels and no DI channels, would this module perform differently than the NI-9472 with Vsup connected to a 5V power supply?

Thanks again!