Status of Digiatal output lines

[Little_Tee]

Hi Hani, Not sure if you'd still like to reply after all this time but I'll give it a try:To be honest, I'm not paying attention to the grounding at all :smileyindifferent: ...I'm using a USB-6251 device and I'm connecting my counter line to the inner cable of the BNC cable and I'm not using the outer (grounding) part of the BNC cable at all. I tried to understand the info you presented in that link, but I don't really know whether to use a pull down or pull up resistor, and frankly I don't really understand fully what the picture says. I just connect the Digital I/O line with a GND line on the board with a resistance in between? As for the rest, I just keep using it the same way?More info on this is greatly appreciated.Tom

[RT4CY]

Hi Tom,It depends on whether you want your default state to be logic high or low.
Logic HighUse a pull up resistor.  Wire one end of the resistor to the center pin of the BNC connector.  Wire the other end to a 5V rail.  This will come from an external power supply.
Logic LowUse a pull down resistor.  Wire one end of the resistor to the center pin of the BNC connector.  Wire the other end to the ground on the BNC connector.
Let me know if you need clarification on this.Message Edited by RT4CY on 07-09-2008 03:01 PM