D.O. TTL Pulse Train, PCI-6143, LabVIEW 7.1

[PJH]

LabVIEW 7.1 (Win XP), NI PCI-6143, BNC-2110

For above software, DAQ board, and connection board:

- is it possible to create two synchronized (simultaneous) digital TTL pulse trains?

- if so, can this be done on the digital lines? or on the counter lines (there are two)?

- are there any examples or leads to help create these two pulse trains? (I'm new to digital output and timing in LabVIEW).

Thanks,

PJH

[DavidMN]

Hi PJH,

It is possible to create two synchronous digital TTL pulse trains.  Since the PCI-6143 supports software timing, the digital pulse trains should be generated on the two counter output lines.  To facilitate synchronization, specify both device counters for the counter input control of the DAQmx create channel block specified for counter output (as shown below).

                                                               

  As far as examples are concerned, I recommend taking a look at the Generating Digital Pulses examples located at Help»Find Examples within LabVIEW (as shown below).

 

David

Applications Engineer

National Instruments

Message Edited by DavidMN on 02-16-2009 12:31 PM

[PJH]

Thank you, David, for your assistance.  I'm still having some difficulty.

Again, my system includes: Windows XP, LabVIEW 7.1, NI PCI-6143, BNC-2110

To clarify, I need:

- two synchronous digital pulse trains with a FINITE number of pulses (10)
- duty cycle = 0.5, frequency = (~1kHz)
- currently using two counter output channels

Using Gen Dig Pulse, and modifiying, I was able to create 10 pulses, but the time between pulses is much to long (~200 ms).  The timing loop does not appear to give the 1 ms spacing that it should.  The front panel/block diagram and output on oscilloscope (channel 1 = counter 0, channel 2 = counter 1) are displayed in images 1 and 2.

Using Gen Dig Pulse Train, I was able to create a continous pulse train (CONTINUOUS SAMPLES on the DAQmx Timing (Implicit).vi).  The front panel/block diagram and output on oscilloscope for default values are in images 3 and 4 below.

Using Gen Dig Pulse Train, I was unable to create a finite pulse train (FINITE SAMPLES on the DAWmx Timing (Implicit).vi).  An error was reported.  See image 5 below.

How might I created 10 pulses with minimal time spacing between the pulses?

Thank you.
PJH

[DavidMN]

Hi PJH,

With regard to the 1ms spacing  you desire, you were able to achieve a 1s spacing at 1Hz frequency for the continuous acquisition using Gen Dig Pulse Train.  Try to mimic that at 1kHz to achieve the 1ms spacing (eg without the timed loop, finite samples).  With regard to the DAQmx error you are experiencing for finite samples generation, check out this KnowledgeBase.

Regards,

David

Applications Engineer

National Instruments