Digital IN and OUT with SCB-68

[Gilles80]

Dear NI experts,

I'm using a SCB-68 with a PXI-6704. With this configuration, I've got 8 digital line. I would like to use 7 of them as digital OUT and 1 as digital IN. To do so, I configured the 7 OUT as "write to digital line" and the IN as "read from digital line". But it seems that the digital OUT don't wrok properly (1.5V instead of 5V, and unstable signal) if the digital IN is working at the same time. I tried to use sequence loops. But the problem stays. So, how can I used 7 digital OUT and 1 digital IN with the SCB-68? In theory, it seems possible, but now I'm little bit lost....

Thanks for you help
Gilles

[Dennis_Knutson]

The SCB-68 is just a dumb terminal block so that has nothing to do with your problem. What I think is wrong is your use of of the high level VIs Write to Digital Line and Read From Digital Line. If you look inside the VIs, they both use DIO Port Config. By default, the one in Write to Digital Line sets all lines in the port to be inpuits and the one in Read From Digital Line sets all to be inputs. Instead of using Write to/Read From Digital Line, use a single DIO Port Config to configure the lines by setting the correct values with the line direction map input. Then when you want to write, use DIO Port Write with an appropriate line mask and when you want to read, use DIO Port Read with the correct mask.