read the current voltage output of an analog output channel

[lmtis]

In DAQmx if you are unsure of the status of a digital output port, you can perform a read on it.  When I try this on an analog output, I get an error.  Is it possible to query the output status of an analog output?  I realize that I could track the status with a variable, but a direct read sure would be convenient.

[Broken_Arrow]

When reading the state of a digital line after you have written to it, you are exploiting the bi-directional nature of digital lines (in some equipment).

Do you have an Analog Input card?

[lmtis]

I guess that would be an important piece of information wouldn't it? DOH!  I am using an NI cDAQ-9178 chassis with an NI 9263 AO module.

[Broken_Arrow]

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@lmtis wrote:

I guess that would be an important piece of information wouldn't it? DOH!  I am using an NI cDAQ-9178 chassis with an NI 9263 AO module.

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That's purely an AO. You'll need some type of AI to read your AO, OK?

[SnowMule]

I think there's a property node that'll let you read the value when the task is configured as a write. ... well, after looking, everything that might work just comes out with an error.

Thinking that your best bet is to wire in a loopback and read an AI voltage channel.  It can be single-ended since the AO lines are ground-referenced.

[lmtis]

Actually I was hoping I could read the setpoint.  I am also using a NI-9472 which is strictly a DO module, and I can read the value of the output lines.  I was just hoping that I could read from the DAQ chassis what the setpoint on the AO lines was.  I can get by with storing the setpoint whenever I change it.

[lis@jiang · Accepted solution]

Hello Imis,

There is no way to read the output in AO modules without physically wiring the signal to an AI module.  You are able to use a variable to read the current output value, like you previously mentioned.

AO channels on multifunction boards, however, can be read through input tasks by internally rounting the channel to read ao vs aoground.

Lisa

[lmtis]

Thank you Lisa.  Just out of curiosity, when I read the value of the DO module is it actually measuring the output, or simply returning the status of an internal buffer?

[lis@jiang]

Hi again,

Can you post a screenshot of the DAQmx code you're using to do this?  (Just so I don't end up giving you wrong information.)

Thanks,

Lisa

[SnowMule]

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@Lisa J wrote:

AO channels on multifunction boards, however, can be read through input tasks by internally rounting the channel to read ao vs aoground.

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How exactly do you do this?

If I understand you right, this does not require a wire between the AO and AI terminal on the device?