Is it possible to read in the current state of the analog output channels on a 7831R?

[arminphys]

Hello,

as the subject says: Is it possible to read back in the current state of an analog output channel on a 7831R?

The purpose is to avoid possible errors due to (potentially wrong) bookkeeping of what I have set to the channels.

I tried to read the channel itself, but it apears to be write-only and I could not find a property or method that allows me to read the value.

Labview version is 8.2

Best regards

Armin

[BillMe]

If you want to see the actual analog voltage you would have to run it back through and do an A/D on it or, e.g, measure it with a DMM. You can keep track of what you programmed (digital value) by wiring the FPGA controls to indicators and reading them back.

[arminphys]

Thank you for confirming this.

In case somebody of the hardware developers listents: Could this be a future option for analog out channels?
I do not mean an additional A/D converter to read the value back (althought this would be a nice option, too) but to read the current digital value that is set to the output.

The main point is here to avoid problems due to wrong bookkeeping.

Best regards

Armin Lambacher

[BillMe]

[I do not mean an additional A/D converter to read the value back (althought this would be a nice option, too) but to read the current digital value that is set to the output.]

You already have the ability to read back the digital value that's feeding the D/A converter. Simply wire the value to an indicator and read it back with your host VI.

The 7831R already has analog in and out, so, technically, you have the ability to loop your analog output back to an input. But there's no point in that since you'll just end up with the same value that's already accessable to you through an indicator.

[arminphys]

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@Bill@NGC wrote:

You already have the ability to read back the digital value that's feeding the D/A converter. Simply wire the value to an indicator and read it back with your host VI.

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Maybe I do not really understand what you mean. I have a control in the target vi that is fed by the host vi. I can wire the control to an indicator and read back this value to the host vi. So far this is what I'm currently doing. At this stage I read back the value that I THINK that I have set. 8-)

My point is that I cannot be sure (from the point of view of the host vi) that the target vi REALLY has set the value of the control to the analog out, especially if a bit more complicated actions happen in the target vi than only setting the value (e.g. doing voltage ramps in the target vi or some other, more involved stuff). If I put some "intelligence" onto the target vi, it can become quite complicated to track everything that is happening there and be sure that the voltages are really set.

I do not say that it is not possible to do this, but an independant readout of the register that controls the A/D converter would be really convenient here.

Best

Armin