USB 6008 Digital Output when connected not working

[Wessam-G]

Hi, i have an external circuit and i want to control it using DAQ 6008 / using LabView , i tested the digital port its working (giving me 5V) but once i connect it to my circuit (PIC16f887) pin its gives me 0V, i dont know why

[Sam_Sharp]

Do you have the correct arrangement of the electrical circuit? Is your sourcing/sinking arrangement correct for your microcontroller?

Check the datasheet here: http://www.ni.com/pdf/manuals/371303m.pdf

It has diagrams showing the correct wiring possibilities.

[Wessam-G]

I connected my microcontroller to light up LEDs and it worked, but i need a port to be control switch using DAQ, the digital generating worked i measured it using my multimeter, but once the P0.0 is connected to the pin (RA4) it stops giving 5V and gives me 0V... should i connect the GND from the Digital port of DAQ some where? cause i dont think i need to

[crossrulz]

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@Wessam-G wrote:

should i connect the GND from the Digital port of DAQ some where? cause i dont think i need to

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What?  You didn't connect the grounds?  You have to connect the grounds together to make sure they have the same voltage reference.

[Wessam-G]

The problem is that i tried that, i connected the GND to the same GND of the PIC and still its not giving 5V once its connected to it

[crossrulz]

As mentioned before, check your microcontroller settings.  Make sure that pin isn't configured at an output or ground.  It could also be that the circuit has a short to ground.

[JanBarton · Accepted solution]

Hi, 

because the NI-6008 has an open collecor output you have to connect a pull-up resistor to +5V.

[Wessam-G]

Thank you Very much ! i forgot about the Pull-Up resistor i connected it now and am getting 5V at the pin. thanks 😄