Read Value of Static Output Card?

[lvb]

Is it possible to read the value of a static output card in LabVIEW or for that matter, any output card?

I am using a NI PCI-6704 voltage/current output card. I would like to read/monitor the voltage/current that a few channels are set at.

I attempted to do this with a DAQmx Read VI, but it returned an error. (I am not on the DAQ pc at the moment, so I don't have the error code)

Thanks...

[Rolf Kalbermatter]

QUOTE(brianafischer @ Sep 28 2007, 01:01 PM)

Is it possible to read the value of a static output card in LabVIEW or for that matter, any output card?

I am using a NI PCI-6704 voltage/current output card. I would like to read/monitor the voltage/current that a few channels are set at.

I attempted to do this with a DAQmx Read VI, but it returned an error. (I am not on the DAQ pc at the moment, so I don't have the error code)

You can usually do that for digital outputs but not for analog outputs. It would anyhow only read the value written in the digital registers of the DA converter and not the actual value on the analog output. To read the analog value there needs to be an AD converter too and that would make the DA converters extra expensive. However most NI-DAQ boards do have a lot more analog inputs so wiring the analog output externally to an analog input will allow you to do what you want. On some boards you can even use internal signal routing lines but programming the according switches is a lot more complicated than a simple external wire.

Rolf Kalbermatter

[lvb]

My solution was to use a functional global that stored the values written to outputs channels in a shift register. There is a "read" command that allows to recover this data. The only limitation to this is that one cannot read values written by other applications.