Communicating with NI9264(Voutput) and NI9209(Vinput) modules.

[nlis12]

I have cDAQ voltage output and voltage input modules.
When I try to have a voltage output (from the output module) read by the voltage input module, the input always measures ~0.9V different than the output. (A few examples)
ie: Vout=10V  Vin=9.1V
Vout=-10V  Vin=-9.1V

Vout=0  Vin=0V

Is there some kind of voltage drop I am missing from the hardware units?
Why don't they read the same and are always offset by ~0.9?

Thanks in advance!

[crossrulz]

My initial thought is your grounds are not properly connected.  Could you supply some code and possibly a wiring diagram?

[nlis12]

My program is very simple.  I am just testing the functionality of these modules.

I have the daq assistant on the right configured for he voltage output with a simple control.  The daq assistant on the left is configured for the voltage input module and outputs its reading to a graph.

Here is the way I am wiring these modules together.

The module on the left is the output and the right is the input.

I am simply wiring output channel 0 to input channel 0. (Blue wire)

And COM to input channel 18. (black wire) 

[crossrulz · Accepted solution]

And how do you have those DAQ Assistants configured?  The image of the block diagram is useless because the configuration is hidden with the DAQ Assistant.

Regardless, you really should have COM being connected to COM.  With this setup, you can use the Reference Single Ended configuration for your Analog Input.

[nlis12]

Thanks!
I had the analog input configured to differential.
Switched it to RSE and got it to work.