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

[YKr]

 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

[ralfn]

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.

[YKr]

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 , so in a first instance I will leave it that way.

[ralfn]

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.