Multiplexing Question 
Author Message
 Multiplexing Question

I am new to labview and I have managed to borrow two DAQ cards and a copy
Labview 4.X.  I have successfully worked through the examples in the
manuals, but I have two things that I can't figure out.

The first is how to read a multiplexed signal.  I have built a PCB board
that has a 16 channel multiplexer on board.  I would like to use the digital
outs to select the channel, then display the output on the appropriate
gauge.  There would obviously be 16 gauges, and I would need each gauge to
hold the signal/value that was last given to it. Is it possible/reasonable
to do this?

The second question I have is how to create a momentary button  I would like
to use this to control a digital pot.  Each time a virtual button is bushed
it would turn on a digital port for as long as the mouse button is held(or
for a specified time period).  This would be used to increase or decrease
the resistance by one step.

I would really appreciate if someone could get me pointed in the right
direction on how to this.

Thanks
Darren Lloyd



Tue, 24 Aug 2004 02:30:36 GMT  
 Multiplexing Question
Darren,

First, I would ask why you need to multiplex the inputs.  Your DAQ
Cards have built in multiplexing, so you could actually bypass yoru
hardware multiplexer.

However, if you can't, I would output the Read Start (or equivalent)
signal to the DAQ Card timing inputs (check your manual) to
synchronize the DAQ with your multiplexer.

As for your second question, just poll a boolean at about 10ms (this
will be your time resolution for button presses) that is attached to
the DIO Write.  This should accomplish what you need in a fairly
easy-to-implement manner.

Hope this helps



Tue, 24 Aug 2004 02:56:46 GMT  
 Multiplexing Question
...

Quote:
> The second question I have is how to create a momentary button  I would like
> to use this to control a digital pot.  Each time a virtual button is bushed
> it would turn on a digital port for as long as the mouse button is held(or
> for a specified time period).  This would be used to increase or decrease
> the resistance by one step.

Right click on the button and look at the mechanical options settings.
You either want the momentary action or the latched Momentary is my guess.

Greg McKaskle



Tue, 24 Aug 2004 08:46:59 GMT  
 
 [ 3 post ] 

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