Problems reading digital channels with DAQmx tasks

[CrizZ]

hello,

i've encounterd a problem with reading the states of my DIO-channels. I use a NI-6023E card for my application and ich need to read the states of the different channels for display on the frontpanel. I've generated a NI-DAQmx-task whitin my application for reading the port of my card.
But every time i start this task, all channels of this port where set to low.
I've created a similar task for writing to single channels and this works fine. what's wrong with my way of handling?
Who can give some advice?

Thanks 🙂

[Jochen]

CrizZ,

whenever you read from the digital lines of a NI-6023E the lines are configured as inputs. This will reset the initial output state of the lines.
There are some special devices like the PCI-6527 that provide readback capabilities to read the current state of a digital line that is configured as output. Multifunction devices like E- and M-Series boards don't provide this feature.

Best regards,

Jochen Klier
National Instruments Germany

[Tom_W_[DE]]

Hi All-

With E Series cards you can actually read from lines occupied by an output task without affecting the states of those output lines.  In order to leave the output states unaffected, you need to disable tristating on the input task.  I have attached a LabVIEW example that shows how to use this feature.

Hopefully this helps-

[CrizZ]

Thanks for your answers. That's the workaround i've already done. This fixed my problem very well.

Kind regards

CrizZ