How to get the state of an output?

[JayCeeBee]

Using PXI with 6527 (digital i/o), 6704 and 6713.
Using LabWindows/CVI.

I would like to know if there is any way to read the state/value of an output that another application (TestStand) has written to.

I am creating an application/GUI that needs two basic modes:
1. To manually manipulate all of the pxi outputs with the application/GUI. This mode will be used to test the DUT manually by flipping swithes and turning dials on the GUI. This mode is no problem.
2. To run this application in parallel with TestStand. This mode will be used to "observe" what TestStand is doing. In this mode, I am hoping that I can get the switches and dials on my GUI to move as TestStand runs the automated test. In order to make this happen, I need to poll the state of all of the outputs in order to update the switches and dials on the GUI.

I want to avoid the following:
1. Looping an output back into an input. I do not want to waste space on my cards.
2. Passing data to and from TestStand. I want this application/GUI and TestStand to be completely independant of eachother.

Thanks,

Jared

[Caroline Bright]

Hello Jared,

There really is no way of accomplishing what you are trying to do with out creating either a physical loop back on the board or passing parameters between the two applications. The only way to do this would be to read the registers of the board and this is not possible. I am sorry that your only shoices are to pass parameters between the applications or to loop back on the board. However, if you need any help with these options we would be happy to help.

Thanks,
Caroline
National Instruments

[Bones888]

Using PXI with 6704

Using Labview 8.0

I am used to operating instruments like Keithley 2400 and 236's where you can read off the voltage being sourced.  Based on this discussion above am I to think there is absolutely no way to read-off the values of the analog outputs on the 6704 and all you can do is write to it?

In that case, is the best way to run this board to continually write to it so you always know what the voltage output is?

Chris

[Kenn_N]

Chris,

Thanks for posting.

The only way to read them off is to actually read the registers themselves, which is basically seeing what value is being sent to the DAC.  If you set the output of a board to a specific level you should know what it is since you are sending the data.  You have access the data you are sending in LV or whatever programming environment you may be using.  There shouldn't be a need to read the values off the board itself.  It would just be a copy if what you just sent it.

Kenn N.

Application Engineering
National Instruments