Duplicate digital output on 32-bit port

[Dave_Le_Pelley]

Hi all, any help appreciated with the last (!) step in a very time consuming puzzle...

I have a PCI-6254 card with 2 x 64 channel breakout cables. Each cable goes to a remote box, each of which essentially runs a multiplexer and acquires analog signals.

Each multiplexer needs an array of  4-bit addresses (eg. 0 to 15) to cycle the multiplexer channels, which I can succesfully generate on port0\line0:3 which are found in cable 1 going to box 1.

My mission is now to duplicate this digital signal in the second cable going to the second box. For this card, Cable 1 has port0\line0:7 and cable 2 has port0\line8:31. I understand that it's a 32-bit port, so I need to send it a 32-bit address.

So I simply (!) want to send identical digital outputs on port0\line0:3 and on (say) port0\line8:11. They should be triggered by the same clock, etc.

Is this possible? However I try so far I can only generate an output on lines 0:3. From what I've read, I'm wondering if the whole of the port is tied up by writing a 32-bit number to the first 4 lines....

Thanks!

[GerdW]

Hi Dave,

yes, that's possible!

Simply create a DAQmx task for "Dev1/di0:3, Dev1/di8:11" to have 8 digital lines in your task…

The other option is to use the whole port and just set the bits/lines you need in your U16/U32 word!

[kosist90]

I'm wondering whether you select all needed channels for the task you create. You can try to create separate tasks also, for example, with needed lines groups, like here:

[Dave_Le_Pelley]

Thanks both, really appreciate your input. I think I tried something like that today with no success but maybe I did it wrong. It ran without errors but just generated the output on 0:3. I'll try your suggestion in the morning (New Zealand evening now).

I think I need to replace the 1D boolean with a 1D U32 array to send the right bit address (I am sending the mux channels in a funny order, something like 4,0,3,6,10,etc). But then I fear that it will only run one task, as the whole 32-bit port is being addressed each time.

GerdW - could you explain how I would go about setting the right bits to send, say, a value to 4 to both sets of lines? I can't get my head around it...

Thanks guys!

[GerdW · Accepted solution]

Hi Dave,

a very simple (and not optimized) way:

Create your 4 booleans for the first 4 lines in the port and set them twice in a boolean array for the whole port.

When you want to optimize this you only need to use integer numbers and some simple math…

[Dave_Le_Pelley]

Done - thanks GerdW!

I set up a task using the whole port and then ran your snippet in a loop for each of the U32 addresses I need to call. Then I converted the Boolean array back to a U32 number for each, then used DAQmx Write with U32, 1 Chan NSamp to write the integer array.

Many thanks, and Kudos richly deserved for such a speedy solution.

Dave