asaikk Posted June 21, 2012 Share Posted June 21, 2012 Hi, On running a ctl document on the DAQFactory Express, I had some trouble in reading the input data. Connecting a LabJack U3-HV to a PC through the USB, the program failed to read the input data. I checked the status of the LabJack U3-HV, which is shown on "LabJack1.jpg". Device No. is set "0" on the ctl document. Then I reinstalled the LabJack, the status of which in shown on "LabJack2.jpg", and this time the program worked fine, reading properly the input data. Since the status of "LabJack1.jpg" does not seem to have any problem, I wonder what is the problem. How should I understand the difference? Link to comment Share on other sites More sharing options...
LabJackSupport Posted June 22, 2012 Share Posted June 22, 2012 I am having trouble understanding your post. In LabJack1.jpg, the U3 looks fine. In LabJack2.jpg, the U3 might be fine, but LJCP can't open it because some other program is holding it open. Also, I see that you have a quite old version of the UD driver. Consider updating: http://labjack.com/support/ud/ud-setup Link to comment Share on other sites More sharing options...
asaikk Posted June 26, 2012 Author Share Posted June 26, 2012 Dr.Sir, Thank you for your comment above which just coincides my experience below. After several trials, I found out the reason that had caused the problem I mentioned. On the state of "LabJack1.jpg", it was LJCP that holded the LabJack open and interfered DAQFactory Express(ctl document) from reading the input signals. After closing LJCP then opening DAQFactory Express, DAQ worked fine. With DAQ kept open, re-opend LJCP showed "LabJack2.jpg"! So my lesson is "LJCP must be closed when opening DAQ"!! Link to comment Share on other sites More sharing options...
LabJackSupport Posted June 27, 2012 Share Posted June 27, 2012 Yes. With the UD driver on Windows, only 1 process can open a device at a time. Link to comment Share on other sites More sharing options...
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