Generate Analog Output Voltage

[jeepers52004]

Hi.

I am working with a cRIO 9023 controller in an 8-slot chassis that also has one NI 9144 Ethercat chassis connected to it.  I am working with VeriStand 2013 SP1.

I would like to generate an analog output voltage through an NI 9264 module that's plugged into the NI9144 chassis.  I'm not having a lot of success finding anything online to help me  accomplish this but I'm sure I'm just not searching with the correct terms.

Can someone point me to an article or tutorial or give me a screenshot or two to get me started?  I found a few things related to adding a DAQ device and using DAQmx but that's not an option for me (at least I don't have any cDAQ hardware.)

Thanks!

[Jiri_K]

Hi,

you need to use Scan Engine Custom Device;

https://decibel.ni.com/content/docs/DOC-15510 

~Jiri

[jeepers52004]

Thanks for the link.  Could you re-post it; it appears to be invalid.

[Jiri_K]

https://decibel.ni.com/content/docs/DOC-15510

there was a space at the end.

You can search for 

NI VeriStand Add-On - Scan Engine and EtherCAT

[jeepers52004]

Hi.  I have this installed already and can access the expansion base NI 9144 from within VeriStand and add modules to it but how do I create an analog output channel from there?

[cody_a]

Once you have added the Scan Engine and EtherCAT custom device, you can right-click on it and select Auto-Detect Modules.  This should detect the 9144 chassis, its modules, and the modules in the local cRIO chassis.  Once the modules are detected, your analog output channels should be available under the 9264 in the 9144 slave section of the sysdef.  If, for some reason, the modules are not auto-detected, you can always add them manually by clicking on the appropriate slot under the 9144, and setting the module to NI 9264.

[jeepers52004]

Hi Cody,

I can see the modules that are installed in the cRIO and expansion chassis.  I've set up a test that cycles a cylinder using the digital IO and am recording temps and pressures.  What I can't seem to figure out how to do is create the analog output for use in a Real Time Sequence or set the analog output value.  How do I accomplish this?  Is it through the profile editor or do I need some type of custom FPGA device?

Thanks!

Michael

[cody_a]

Under the 9264, you should see all 16 analog output channels, as shown in the screenshot below.  These channels can then be accessed from anywhere else in your system (map to other channels, use in calculated channels, control via workspace object, change via RT Sequence, etc.).

What do you actually want to do with the analog output channel?  How is its value set?

[jeepers52004]

Hi Cody,

So far so good.  I can see exactly what you have shown in your screenshot.  I would like to be able to ramp an analog output channel full scale in both directions.  I tried adding a variable to the real time sequence (even though I've not tried anything programmatically to change the output value) and linking it to one of the analog output channels.  I then added a control to the workspace.  When I deploy the configuration file and run the stimulus profile that calls the real time sequence and starts the workspace, changing the value manually in the output channel control does not actually produce any change in the physical output of the module. 

It seems I'm missing some small or large detail to implement this correctly?  Let me know if there's something I can post that will help shed some light on what I'm doing wrong.

[jeepers52004]

I haven't nailed down exactly what I did wrong yet but I tried things again this morning and I am now able to control the analog output voltage.

Thanks to all for the assistance!