ni usb 6008

[pusavec]

Dear,

I have your USB measurement device (ni usb 6008) and have one problem: When I turn on my computer, all the digital output pins on this measurement device are high – why? They must to stay low until I turn the program to control them and put them to the high level.

Thank you in advance.

Franci Pušavec

franci.pusavec@fs.uni-lj.si

University of Ljubljana

Faculty for Mechanical Engineering

Askerceva 6

SI-1000 Ljubljana

[devchander]

This device has an internal 4.7K pull up resistor, so ALL your DIO pins show up as default High. ( https://www.ni.com/en/support/documentation/supplemental/18/internal-pull-up-pull-down-resistor-valu... )

Looks you need to use a suitable pull down resistor.( see this link for choosinf pull down resistor http://digital.ni.com/public.nsf/allkb/018c0fb5acb0322186256f390051888c  )

Hope this helps

Regards

Dev

[GDE]

Franci,

Devchander is correct that the 6008 has a 4.7kOhm pull up resistor internal to the device causing the behavior that you are seeing. However, attaching another "pull-down" resistor is not the answer to achieve a logic low start up state. The KB that Devchander linked talking about using a pull down resistor, was in regards to the 653x series of DIO cards only, and was not meant to be applied to the 6008. Attaching a pull down resistor to the 6008 will essentially create a voltage divider and will cause the device to not work properly. You have two options that you can go with to obtain a low start up state. You can either put an inverter on the lines that you need to start low. Or you can look into another board that does support programable power up states (such as the PCI 6503, or other devices that support user defined power up states). Hope that clears up things a bit, feel free to post back if you have any other questions.

-GDE

[devchander]

Oh, I did not Know that about USB 6008's!

Thanks a Ton, GDE.

[pusavec]

Thanks, i have solved the problem with PNP tranzistors, so I achieve inverted signal and chanse to control devices with stornger current

 needed to turn on.

Franci