Setting 6534 for tristate in CVI

[Nivled]

All literature associated with this card indicates that it can be setup for tristate.  When I attempt to Configure the Power On State to Tristate I get an error that this device does not support it.  Does any one know how to set up the PCI 6534 in tristate using Labwindows/CVI?

[Havarti]

Im have had limited exposure to the 6534 but I don't believe the 6534 lines can be tristated.  I did a quick search of the 6534 user manual and tristate wasn't mentioned which seems to back this up.  If it turns out I am wrong, you may want to look into if you are trying to tristate a line while it is configured as part of a port which is not possible.

Hope this helps.

Brian

[Nivled]

Maybe I'm thinking of the wrong thing I thought Tri-state was the same as Standard output or  Active drive, as mentioned in the 6534 Help file under "Digital Lines and Ports" > "Drive Type" > "Active Drive" as well as page 2-2 in the 653X manual "Standard Output". 

 I have the cards connected in parallel to my test board.  One 6534 is dedicated to reading, the other is deticated to writing.  I was under the assumption that because you could parallel the 6534 cards it would have to have an option for tri-stating otherwise the test card, and the 2-6534's will fight each other for control of the bus.  (the test card will try to drive some of the bus lines low to put information on it while the 6534's will try to drive them high).  If I am on the wrong path could someone point me in the right direction?

[Tom_W_[DE]]

Hi Nivled-

You're absolutely correct that you will need to tristate your output hardware to avoid double-driving the bus lines.  The NI-DAQmx CVI function to perform this step is "DAQmxSetDOTristate(TaskHandle taskHandle, const char channel[], bool32 data);" and only applies to output tasks with the 6534. 

I found this information under the Channel Properties section of the NI-DAQmx C Reference Help (Start>>Programs>>National Instruments>>NI-DAQ).   Hopefully this helps-

[Chris_N]

That worked...thanks.

[Tom_W_[DE]]

Chris-

I'm glad I could help.  Thanks-