Problem Generating the Analogue Output on PCI-7342

[Ron Liou]

I'm using Axis-1 of my PCI-7342 for the servo motor control with encoder feedback

and trying to output the encoder velocity on the analogue output of Axis-2 which is currently unused.

For testing purposes, I output a constant 16383 (half of 32767) to the analogue output

via Load DAC.flx continuously but there is no voltage reading on the motion board.

I have read

http://digital.ni.com/public.nsf/websearch/102BE3EEED8A8B0DC1256EDA0059EC47?OpenDocument

http://forums.ni.com/t5/Motion-Control-and-Motor-Drives/analog-output-voltage-from-UMI-7764/m-p/5219...

http://forums.ni.com/t5/Motion-Control-and-Motor-Drives/Configuring-the-Analog-Output-of-PCI-7358-Mo...

and configure my Axis-2 to be a stepper motor. I have also tried to disable Axis-2. None of these works for me.

Furthermore, I tried reading the DAC value using Read DAC.flx right after Load DAC.flx is called.

The value was correctly showed on the screen. (Please see the attached figure) 

I am really struggling now. Please, please, please help!!!

Any possible solution is fully appreciated!

Ron Liou

[ZachAttack]

Interesting problem.  What are you using to check if the voltage is being output?  If you are using some sort of multimeter, where are you putting the leads?  I find it interesting that it says it is reading the correct voltage.  What version of NI Motion do you have?

[Ron Liou]

Hi Zach,

Thanks for your reply. I'm currently using an ocilloscope to output the voltage from AOUT2 and AOGND.

Basically, I screwed in 2 copper wires from the motion card to the BNC cable which connects to the ocilloscope.

I have also tried to output this voltage on one of the differential input of NI-USB 6008 DAQ.

Unfortunately, none of these gives me the desired output.

And I'm using NI-Motion 8.1.0.3037.

[Ron Liou]

I am also thinking if this has anything to do with the hardware setup.

Because everything on Axis-1 of UMI-7764 works fine, I wonder if Axis-2 is not connected.

I am not sure about this because the system was installed while I was away.

Thank you for your time.

[ZachAttack]

First, let try upgrading to NI Motion 8.2. It could be how you've configured your hardware.  Could you explain how you have your hardware connected?  A summary of all devices and cables would be great so I know what you're working with.  Thanks.

[Ron Liou]

The summary of the system setup is attached. Please have a look

and let me know if any more information is needed.

Thank you

Ron Liou

[ZachAttack]

I'm still looking into other possible problems that could be occuring.  Have you considered just using one of the four analog outputs instead of outputing a voltage through Axis 2?

[Ron Liou]

Yes, I have tried output the voltage through AO3 (on Axis-3) and AO4 (on Axis-4). None of them gives me any voltage signal.

Thanks,

Ron Liou

[ZachAttack]

Have you tried using the analog outputs on Axis 1?  Make sure this axis is enabled before trying this.

[Ron Liou]

Hi Zach,

I have tried switching Axis-1 and Axis-2. In other words, use Axis-1 for analogue output and Axis-2 for servo motor control.

This time, I can get the correct analogue output when calling 'Load DAC.flx' but I cannot control the motor.

There seems to be no output from Axis-2 to the motor drive.

Thanks,

Ron Liou