Write timed digital out with 6501 VB

[stordansker]

Hello,

I'm trying to determine if the NI USB-6501 will be able to write digital values out on all 24 outputs simultaneously (and reliably) every 10msec using VB. 

I've downloaded the NI-DAQ and looked through the VB examples on writing digital out lines and it seems simple enough.  Considering I haven't purchased the 6501 yet, I'm curious if anyone has done something similar to this before or if maybe I'm considering the wrong hardware and/or software. 

Is it even possible to software drive events down in the 10msec range?  Will the 6501 response be fast enough?  Can the functions in the VB examples write out to all 24 pins simultaneously or just 8 at a time?

Thanks in advance for any help provided. 

[Dennis_Knutson]

You can write all 24 pins at the same time and the 6501 response will be fine but your os will introduce quite a bit of jitter (10's to 100's of ms). Using a card with hardware timed digital I/O would be the simplest way to ensure your timing.

[stordansker]

Ok.  I think I have decided to go with the 6501 anyways as the USB interface and 24 writeable pins is far more important than the possibility of software timing jitter for my application.

I have begun to look through the sample code (VB) included in the NI-DAQ package for writing out digital outputs and read through some of the documentation.  I'm thinking of modifying the WriteDigChan sample solution to write to 24 pins instead of just 8 like the example does.  Would I need to create a new and create a new channel for each port on the 6501 (P0,P1,P2) or is there a cleaner and more efficient method of simultaneously writing out to all 24 pins?

[Dennis_Knutson]

I think that all you need to do is specify Devx/port0:2.