Output options for NI 9401

[mcrobert]

I am currently evaluating the CompactDAQ platform as a replacement for some of our older test equipment.  In order to interface to my existing test setup, I need a digital I/O module that can tristate its outputs.  I was looking at the NI 9401, but cannot tell from the manual if this module can do TTL high, low, and tristate.  So, my question is, can you program the 9401 to tristate it's output? 

Thanks in advance for any info. that you can supply on this topic.

Rob

[McKala[DE]]

Hello Rob,

The NI 9401 does not support tristate mode on digital output lines.  You might consider either an M-Series board or a PCI-653X series board instead.

Regards,

[KyleBryson]

Rob,

The 9401 is bidirectional, and when set to input, will function as a tristate output.  There are a couple of things to keep in mind with this module: 1) When set to input, the lines still have a weak pulldown resistor with a min. value of 45 kOhms, as specified in the manual.  2) Line direction may only be controlled in banks on the 9401.  This means that DIO 0:3 must all be set to the same direction, and 4:7 must all be set to the same direction.  I don't have enough information about your setup to know if this will provide a complete solution.

Please post any additional questions, or more details about your application if you're still not sure whether or not this solves your needs.

Thanks,
Kyle Bryson
National Instruments

[pdebeule]

Hello,

I already have the cDAQ platform (with NI9401) and need to extend it with a tristate DO.

However, I am not able to switch the banks from output to input without buying an extra module.

Is there one of the 15 digital cDAQ modules that offers a tristate DO?

Regards, Pieter