Why does my PCI6534 keep missing triggers?

[John E.]

Hi,

I'm using a PCI 6534 to output a series of triggered, serial command words (around 150 bits per word) clocked out at 1MHz. I need to output around 200-300 of these words, with as little latency between words as possible.

I am running into a problem with the card missing some triggers. I am using a TTL pulse with a 1.5us pulse-width to trigger each serial word. I have not, however, been able to get lower than 10ms between each strobe without the card missing a few. I assume that this is caused by the latency in NI-DAQ's C++ drivers. Is there any way to speed this up? I am looking for a period of <1ms between serial words.

I have tried putting the whole set of words into the serial buffer and pu
tting the card in loop mode, but then I loose my ability to trigger each word. What would you suggest?

Thanks,
John E.

[Michael_S.]

John,

The use of a PCI-6602 counter board in conjuction with the PCI-6534 will accomplish what your application needs.

Basically, we can setup the PCI-6602 to ouput X number of clock pulses everytime it receives a trigger. In this case every time you send a trigger to the PCI-6602, the counter will output X number of pulses to clock the 6534 which will in turn output X number of words. Then the 6602 will wait for the next trigger to output X number of pulse to so the 6534 can output the next X number of words and on and on.