Hi,
I'm using a U3-LV to send short signals via Matlab to my EEG system (as I have described here http://forums.labjack.com/index.php?showtopic=6679 a while ago).It all works quite nicely, but I just noticed two issues:
1: If I send a signal to channel FIO1 (either using PUT_DIGITAL_PORT or eDO), I also end up with a signal on FIO2 (and vice versa).
2: If I send a signal to channel FIO1 or FIO2, I only receive and output voltage of ~18V, whereas I receive ~32V on the other FIOs.
The problem is that I need to send specific signals to the EEG system (i.e. if I send a signal via channel FIO1, I need to be 100% sure that only FIO1 is active) and that I need a rather high voltage for the EEG system to detect the triggers. As I have only recently noticed this problem, I was wondering if there is any way to set the output voltage and whether I have accidentally set channels to be coactivated.
Thanks a lot for your help and support.
Julian
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Are FIO1 and FIO2 jumpered on your U3? In that case if one line is output-low and the other output-high, you will see a voltage close to 1.6 V (that is my setup's measurement) coming from both lines. That might be the ~18V (do you mean ~1.8V?) you are seeing. Digital I/O's use ~3.3 volt logic.
If that is not the issue, first make sure you are running the latest U3 firmware. Use LJSelfUpgrade to check your U3's firmware and to update it if needed. If that doesn't help, please provide your PUT_DIGITAL_PORT call and how you are setting your lines. eDO will only tell the U3 to set one line. Also, please describe the connections on your U3.
Hi,
thanks a lot for your quick reply!
In fact, a device down-stream caused FIO1 and FIO2 to be jumpered due to a loose connection. All works fine now.
Cheers, Julian