AO amplitude transitions from 0 to 10V (and back to 0 again) within running VI

Question

Hi,
I have a NI PCI-6225 multifunction DAQ that I am using for Geophysical measurements.  I am applying 10V from one AO channel and measuring voltage differences with 49 AI channels.  For the method I am using I must follow these steps:
1.  Set voltage out = 0V
2.  Take Self Potential measurements from all AI channels
3.  Turn the AO channel ON with an applied voltage = 10V (1Hz square waveform)
4.  Take measurements from all AI channels
5.  Loop back to step # 1
At the present, I have the VI set up to apply the AO of 10V and to take measurements over time.  The only thing missing is to take the Self Potential measurements while the applied voltage is at zero volts, run the VI in its current configuration, and then to start over again.
I am using the Express VI DAQ Assistant to set up all of the electrodes in the array for the applied voltage and the measured voltage and am able to do everything needed except include the applied voltage to zero for the Self Potential measurement.
I have attempted to use the DAQmx subVI's "Stop" and "Clear" (and any other combination of subVI's) to allow for the channel to be freed up within the VI, but the output channel then gives an error signal in the next cycle of the loop.
I am not sure what else to do, so any suggestions will be greatly appreciated.
Thanks,
Dylan
Note:  Attached is the VI in which the problem is occuring.  I have this VI as a subVI within a timed loop that will execute every 60 seconds.
Attachments:
Testing_Voltage_Measure.vi ‏339 KB

Answer 1

Dylan,
I think you may have posted twice.  I just wanted to make sure your question has been answered.  Let us know if you have any further questions.
Link to other post:
http://forums.ni.com/ni/board/message?board.id=250&message.id=24523
Good luck with your application.
Regards,
Neil S.
Applications Engineer
National Instruments