On-board memory limit workaround?

[Raymond Tsang]

Hi all,

I'm using a PCI-6250 to pulse an LED at ~1kHz frequency. The pulse train looks like: 1 0 1 0 0 0 0 .... (all zeros until another pulse ~1ms later)

Each bit is 100ns. Simple calculations tells me that I need to put 10k bits to the on board memory every 1ms which is more than the 2k bit limit on the board. (btw, I can't find any DIO board with on-board memory > 4k)

If I do not use on board memory, LabVIEW complains about the data transfer is not fast enough.

Since from the 4th bit onwards, the pattern is just plain zeros, is there a way to work around the memory limit problem?

Thanks so much!

Ray

[jdunham]

QUOTE (Raymond Tsang @ Mar 2 2009, 02:55 PM)

I'm using a PCI-6250 to pulse an LED at ~1kHz frequency. The pulse train looks like: 1 0 1 0 0 0 0 .... (all zeros until another pulse ~1ms later)

Each bit is 100ns. Simple calculations tells me that I need to put 10k bits to the on board memory every 1ms which is more than the 2k bit limit on the board. (btw, I can't find any DIO board with on-board memory > 4k)

If I do not use on board memory, LabVIEW complains about the data transfer is not fast enough.

What about

C:\Program Files\National Instruments\LabVIEW 8.6\examples\DAQmx\Counter\Generate Pulse.llb\Gen Dig Pulse Train-Finite-Retriggerable.vi

It uses counters instead of DIO, but it might get the job done.

[Raymond Tsang]

QUOTE (jdunham @ Mar 3 2009, 07:50 AM)

What about

C:\Program Files\National Instruments\LabVIEW 8.6\examples\DAQmx\Counter\Generate Pulse.llb\Gen Dig Pulse Train-Finite-Retriggerable.vi

It uses counters instead of DIO, but it might get the job done.

Thanks for your help, but it looks like it doesn't "double pulse".

I'll play with for a while, or maybe just buy a new card, e.g. PCIe-6535, as a last resort.

Ray

[JCC]

QUOTE (Raymond Tsang @ Mar 2 2009, 10:55 PM)

Hi all,

I'm using a PCI-6250 to pulse an LED at ~1kHz frequency. The pulse train looks like: 1 0 1 0 0 0 0 .... (all zeros until another pulse ~1ms later)

Each bit is 100ns. Simple calculations tells me that I need to put 10k bits to the on board memory every 1ms which is more than the 2k bit limit on the board. (btw, I can't find any DIO board with on-board memory > 4k)

Hi,

how many 1s and 0s do you want write per one second?

[Neville D]

How about a quick call to NI to find out which hardware will work best in your special case? This is exactly what Application Engineers and your local NI rep are there for.

Often they can recommend hardware that you never knew existed in their catalog. Maybe you need an FPGA card, I don't know..

Neville.

[Raymond Tsang]

Thanks for your advice.

I've ordered a new card... PCIe 6535 with more on board memory (64k).

[jdunham]

QUOTE (Raymond Tsang @ Mar 5 2009, 12:54 PM)

Thanks for your advice.

I've ordered a new card... PCIe 6535 with more on board memory (64k).

I sent you a PM. If you are interested I can help you get it working with a garden-variety DAQ card.

Cheers,

Jason