Counters and frequency measurement using NIDAQ

[Roland Keir]

Hi Everyone,

I am in the middle of writing some code in Delphi
to access a couple of nidaq cards and need some advice.

I can measure a ttl signal via a counter
using the gpctr routines successfully.

(from this I can get a count rate - we do light scattering).

However, the gate signal for the counter is from an
external function generator.

Instead i want to remove the func gen. and use the counter0 for
pulse_train_generation
and then use this as the gate signal for counter1.

(I can get pulse_train_generatation working successfully).

I am using a PCI-6025E (but can swap back to an AT-MIO-16E-10).

My problem is that the code complains of no available DMA channel
(error -10455).
i.e. I can ND_PROGRAM cou
nter0 for pulse_train_generation (successfully)
but the error occurs when I then try to ND_PROGRAM counter1 for
GET_BUFFERED_EVENT_COUNT.

I have some comments from the NI website that indicate
that you need both counters for one frequency measurement
(and instead should use an Analog output channel for gating).

But have also seen comments from NI that indicate that
you can use counter0 as a gate for counter1.

Basically, I'm confused and would appreciate some advice.


Cheers,


Roland


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Dr. Roland I. Keir Phone: +61 8 8302 3058 (Lab) / +61 8 8302
3024 (Office)
Laser Light Scattering and Materials Science Group
School of Electrical and Information Engineering Fax: +61 8
8302 3389
University of South Australia E-mail:
Roland.Keir@UniSA.edu.au
Mawson Lakes, SA 5095

www.laser.unisa.edu.au
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