Measurement Computing USB-1024LS DIO always high

[Tazam]

I'm using a 1024LS to read inputs into 1stPortA/DI 0 - 7 and 1stPortB/DI 0 - 7 (16 channels). The Labview vi has boolean indicators that will light up if the input to any of these ports is >4.5V. The problem is, each of the 24 DIO ports on my 1024 are outputting 5V automatically (4.7V on DMM), which gives me incorrect values when I actually run the test. 

I am able to set each DIO port OFF (0V) programmatically, however, as soon as I move on to reading it, the value is 5V. 

The 1024 User Guide mentioned '..if configured to input..' suggesting the device can be set as an input somehow. I tried using InstaCal but the Config button only has options to change device ID and flash the device LED.

Anyone knows how I can reset the 1024 to be input only? Thank you!

Edited September 23 by Tazam

[Fausto]

Hello @Tazam.

The USB-1024LS powers up with the digital channels in Input mode.  Additionally, all digital channel pins are pulled up high to Vs via 47 KOhm resistors by default, which is  why the Labview vi boolean indicators light up for this device.  In other words, the inputs themselves will float and read ~5 volts when nothing is connected to a terminal. 

(NOTE: Digilent does not offer a service to modify the device to pull the digital channels low to ground.  Also, this daq device is not repairable.)

Please reference the following forum post.

 

Lastly, use InstaCal to test your device, without any external signal connections.  Does your USB-1024LS module pass the Internal DIO tests in InstaCal?

 

 

Regards,

Fausto

[Tazam]

Hi Fausto, 

Thank you for your response! This is exactly what I needed to know. I tested the device with InstaCal and it did pass just like your image. I modified the board as per your instructions and now the digital ports are all pulled down. Working perfectly!

Thank you!