Hello,
You can control individual digital lines or ports using the DAQ assistant, but the digital ground is always set to ground. To control the lines or a port when you open the DAQ assistant:
1. Select Digital I/O
2. Select line output or port output depending on your application.
3. Select the your PCI-6221 card and then select the line or port you would to control
4. From there you can hit test to verify everything is working properly
5. Select ok and wire a constant or control into the data input and run the program.
There are also some LabVIEW examples for this. If you go to the Help>>Find examples>>Hardware Input and Output>>DAQmx>>Digital Generation: write to chan.vi and the write to port.vi.
Regards,
Hal L.
