Digital I/O

[Munson1027]

So I have a nagging suspiscion that the answer to my question is simply "It isn't possible" but I'll ask anyway.

I have a cDAQ-9172 and I am using NI-9472 modules in it.

What I want to do is very similar to this example:

http://zone.ni.com/devzone/cda/epd/p/id/5239

The difference being, I want to be able to control different lines at different 2 frequencies

For example: lines 0-3 cycle through pattern A at frequency Alpha, while lines 4-7 cycle through pattern B at a frequncy of Beta.

Is this possible witha single module? 

I know I can do it with two modules, but would prefer to use just one.

Thanks

Matt

[Steven_K.]

Hi Matt,

You are correct, you cannot have different frequencies on different outputs of the same digital output module. This is because those lines share the same timing circuitry. Like you said, this is possible with using two modules.

[Munson1027]

Pretty much what I had figured, although I did think of an awkward to implement soultion:

You can write a subVI that correlates ths slower of the two frequencies to the faster on, and the create a waveform for all lines that is at the faster time base. Of course, correlating the two frequencies would be easy if they are integer multiples of each other, but if you wanted to allow arbitrary frequencies, the correlation can get pretty hairy...

Anyway, I already have the PO in for a new module, but if there are delivery delays, I might implement this...

Matt