How do you obtain high impedence on digital output line?

[Dekay]

I would like to switch between logic zero and high impedence on the digital output lines of a 6115. However, there are pullup resistors that prevent the output from floating.  Is there a way around this? Ideally, negligible current will flow through devices connected to the digital output lines when the output is tristate, high impedence.

[Otis]

Hi Dekay,

I pulled this from the S Series Help

Each line has a weak pull-up resistor connected to it, as described in the specifications document for your device.

It sounds like you want to simply switch your lines from an output with logic 0 to an input which will have a high-impedance state.

Maybe if you tell us more about what it is you are trying to do we could give you some better details.

Regards,

[Graziano]

Hi!
   You should be able to do it in max, in device configuration.

   If you're programming in CVI, have a look at this function:

    DAQmxSetChanAttribute (, "", DAQmx_DI_Tristate, );

   (see help for further details....)

   Hope it helps!

graziano

[Dekay]

Otis -

I would like to use the digital lines to selectively create or eliminate a ground path. I have a resistor with one end connected to DIO0 and the other to a circuit in which I would like to change the resistance. Switching between DO0=0 and DI0=high impedance was expected to put the resistor in the circuit or take it out, but it still puts 5V out on DI0 when in hi-z.  A program sample is attached.

Thanks

[Michael.Phillips]

Hi Dekay,

Instead of creating a Digital Input Channel on the same line as the Digital Output Channel, just use a single Digital Output Channel and use the DO.Tristate property to tristate the line. Your code has two tasks sharing the same line. Let us know if this helps.