Digital I/O

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How to send a digital pulse from Labview to an external I/O device



I am rather new to the Labview environment and I'm engaged in a project that makes me face challenges every now and then (good right? 🙂 )

So my new challenge is that I have in my LV program a logic that generates a pulse from user input of rising and falling edge CAD degree values. And I want to send this pulse to an external (physical) I/O device. Here is the environment I am working on: 


I am running Labview 2011 on Windows 7

I have PXI-1073 chassis connected to my PC via PCI-Express 

And I have the SCB-68 M-series connected to slot #2 of the PXI-1073 chassis. 


I would like to know how I can send my pulse from LV to a specific pin on the I/O device. I am running through the pin configurations from the user manual and the PIN out diagrams on myself but I am having difficulty (rather haven never done such a thing till now) from the programming side. 


I appreciate the prompt help. 



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Message 1 of 24

The SCB-68 is just a dumb terminal block. Please provide the actual DAQ device.

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Message 2 of 24
Here are again the set of devices I am having. Sorry for the incomplete or not informative descripition I gave earlier.
1. NI PXIe-1073 chassis
2. NI-PXIe-6361 multifunction DAQ
3. NI-PXI-5105 high speed digitizer
4. NI SCB-68 I/O-card
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Message 3 of 24

The 6361 has digital I/O that has both hardware and software timed signals. Look at the DAQmx digital generation examples (Help>Find Examples>Hardware Input and Output>DAQmx).

Message 4 of 24

There are actually a LOT of examples out there. Tnx. I found the *Gen Dig* help example to be something to start out with. I'd like to control my pulse using the rising and falling edge time instances. The thing is this particular example is using Counter output but I prefer a Digital Output where I'd be able to read my set value from one of the pins on SCB-68. Am I totally getting it wrong here? 

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Message 5 of 24



I have the attached VI which I would like to have a help with to bring it to the working state to fulfill my requirements. Correct me if I am wrong, but I understand the VI to work in the way that using the counter output pulse as a guide/condition so that as long as the task of generating the pulse out of the 'CO Pulse Time' VI is going on or there is no error during this task, to write the boolean value to the output line. So I'd like to use this same manner such that I would be able to write to the digital output line but during the high time of the pulse.  

My understanding: Initial delay is 0 up to T1 

                            High time is T1 up to T2

                            Low time is T2 up to  T3













I would appreciate if anyone helps me to the right direction if I am off track and I would like to send the Boolean HIGH to the digital output line only during the high time of the pulse from the Counter Output. 

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Message 6 of 24
One quick question: During this case what is the pulse duration? Is it T3 - T1 or all the way from 0 to T3?
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Message 7 of 24



Are you only sending 1 pulse to your external device? A digital pulse is associated with Marks/Space ratio, and I think in your case, you are trying to send digital highs or lows (0, 1). In essence, your 'pulse' can be viewed as a message I believe and it should have more than just a '1'.


Can you provide a longer set of values? 

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Message 8 of 24

Hi The_Sugarman,

Thanks for the reply! Let me give you the scenario so you better understand my requirement:

My intension is that every iteration of a while loop, there comes in an array of CAD data which has a range of [-180,180] and from the FP, the user is to choose two CAD angle values i.e the rising and falling edges of the pulse generation. Based on the user input I translate the CAD values to time values and then I'd like to use these to generate a pulse using 'CO Pulse Time'. So every cycle or every iteration of the while loop I'd be sending one digital pulse characterized by the intial delay, high time, low time properties. I was using one of the Labview shipped examples *Counter Output* and it is sending 5 V pulse. But I was not quite getting the pulse according to the settings of the time parameters.

I have attached the example VI I am working on.

I appreciate your prompt reply.


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Message 9 of 24

Sorry for the late reply Henok.


So you want to send A digital pulse everytime a CAD value (in angles) is choosen? Does this pulse have to have certain parameters? Like amplitude, pulse width etc? if so, do you know what they should be or do you just want to send a random pulse?

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Message 10 of 24