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Digital Output on framegrabber PCIe - 1427 defaults at high instead of low at PC startup

 Hi,

 

Everything is in the title.

 

I am using a PCIe-1427 framegrabber to acquire images from a PhotonFocus Camera.

I would like (and already managed to program) to use the digital lines to trigger external devices.

 

My problem is : The output of all of my digital lines is set to high as soon as the PC turns on.

 

I have tried different suggestions found in the forum already but I don't get the DO to output 0V when idle.

 

Here is what I have tried until now :

 

Inserting a pull-down resistor between signal and ground lines (47 kOhms)

(as suggested here : http://forums.ni.com/t5/Machine-Vision/How-can-I-set-a-trigger-default-to-low-instead-of-high-on-a-1...)

 

Changing the camera file to allow default output to be set to either low or high.

(as suggested here : http://digital.ni.com/public.nsf/allkb/4E6F9A0BDAE9BFDB862572D80053DFB7)

 

As the digital lines go straight up to HIGH as soon as the PC is powered, even before entering Windows, I am wondering if there are jumpers which have to be set. Any ideas or solutions ?

 

Thanks a lot for your help

 

Yves

 

 

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Hi Yves,

 

on page 7 of the "Getting Started with the NI PCIe-1427"-manual you can see that the outputs contain a 10 kOhm pull-up-resistor to Vcc (+5V):

 

http://digital.ni.com/manuals.nsf/websearch/00BF266D08D6440386257257005C3CF3

 

Thatswhy you see a high a the output.

 

To get a low you can connect a resistor of 1 ... 2 kOhm between output and ground. (47 kOhm are too high.)

This should pull-down to output to low.

 

Hope this helps.

 

With best regards,

Ralf N.

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Thanks a lot for pointing that out. I missed that part in the manual.

 

Although, I won't try this immediately because the device I am triggering works just as well with falling edges Smiley Happy, so in a first instance I will leave it that way.

 

 

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Hi Yves,

 

great that you found another solution.

 

Using falling edges has the advantage that you save the external resistor.

 

Have a nice day.

 

With best regards,

Ralf N.

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