E series: how to synchronize DIO, AI and AO precisely

[T_alexis]

Hi all,

Excuse me if this question is already posted somewhere in the forum. If it is solve, I am very pleased to have its links. Thank you.

My problem is that

1. I want to synchronize DIO, AI and AO with the 6071E board. According to my understanding, this can be done either as software or hardware timed. However, my DIO in 6071E seems to be supported only in software. Is it correct? if yes,  how precisely is the software timed?

What I did for AI, AO synchronization is hardware digital triggering with the pins PFI0 and PFI6. The acquisition starts when a high value is written in the digital output P0. Does my DIO also synchronize in this case or I miss understood something?

2. I want to use the digital output to send a TTL pulse to a switch after triggering a certain time (for example, 400 us). But I cannot control the time of reading/writing a value to digital output. It varies.

Can I use counter or any thing more precisely to output that TTL pulse?

Any suggestions are welcome. Thank you.

Btw, I use Matlab with data acquisition toolbox. I also have the ANSI C reference guide.

[Michiel_H]

While hardware timed DIO is available on the M-series, it is not on E-series. The exact precision of software timing depends on the specs of the hardware, other programs running etc. On a normal windows PC, don't expect the precision to be < 1ms.

What I suggest you do is indeed to use a counter. Counters are hardware timed and capable of generating a pulse with a specified low & high time. You can then easily trigger the counter with the same trigger you use to launch the acquisition. The pulse will then be generated after the trigger arrives.

I suggest you take a look at the ANSI C examples on how to use a counter to generate pulses.

[T_alexis]

Thank you very much Michiel for the suggestion.

I tried with the counters. But the problem is the DAQ 6071E I used only have 2 counters, but I have 3 switches to control. The first switch is ON with the stimulation train pulses, the second is ON after about 200 us and the third one is ON after each stimulation pulse finish.

Is there any way that I can reuse the 1st counter for the 3rd switch?

Thx

[Michiel_H]

Altough counters can be reconfigured while the task is running, however the reconfiguration will probably be to slow in your application. You might try it out. If this doesn't work, I'm afraid you will have to find another solution (change DAQ-card, add another device...) since there is no other way of getting a hardware timed digital pulse out of an E-series device apart from using counters.