I need help sending a pulse stream.

[AliasAlias]

I am using NI-USB-6229, with LabVIEW 8.5.  I am trying to send and receive a 16-bit pulse stream (with an additional start and stop pulse).  I need help getting that set up.  I want to pull each of the bits from a variable of some sort, so that when I send it out, I specify which bits should be hi or lo.  When I read in a similar signal (on another digital line), I want to be able to read whether each of the bits are hi or lo, and send them to LEDs on the screen.  I need the output to run repeatedly, from the NI-USB-6229, not from my computer.  I have not found something that gets me started, on the website or examples. 

[jaced]

Hi,

In order to perform this operation with your device you will need to use a counter to generate a clock signal for your digital output. The digital subsystem does not have its own dedicated internal timing engine. Therefore, a sample clock must be provided from another subsystem on the device or an external source. The following two Developer Zone documents discuss how to accomplish this, while performing an input.

M Series Hardware-Timed DIO with Counter Clock Generation

DAQmx - Using a Counter as the DIO clock for M Series

The method in which you will build the digital waveform will depend on the type of variables you will be pulling this information from. Here is a tutorial on building a table of digital data.  In regard to reading in your digital data and displaying it on screen I would look at the Read Dig Chan.vi example which can be found in the NI Example Finder>>Hardware Input and Output>>DAQmx>> Digital Measurements. You also mention that you would like to have this output come from the hardware only. You device has a 2047 sample FIFO buffer which will allow for buffered output but I am unsure what you mean by “not from my computer” could you clarify on that.

[AliasAlias]

You also mention that you would like to have this output come from the hardware only. You device has a 2047 sample FIFO buffer which will allow for buffered output but I am unsure what you mean by “not from my computer” could you clarify on that.

It is my understanding that I can set up the samples, and then let the NI-USB-6229 run continuously, once the hardware has received the set of bits desired, without relying on the computer to control it, to ensure that there is a dedicated control of the output, so that the timing will not be impacted by other operations.  Is this correct? 

Thanks,

Melanie

[jaced]

Hi Melanie,

Thank you for clarifying what you meant, I believe the this Knowledgebase articles titled Analog Output Regeneration Modes and Data Transfer Request Condition for Continuous Analog Output using NI-DAQmx will be great resources for you please review these documents and post back if you have any further questions.