ground lines

[willist2]

Hi, I have a USB - 6008 DAQ and i'm trying to link it to an electronics board for an experiment. I know about the digital and analogue lines needed, but i'm confused as regards to ground lines. I've been told I need four, but I'm not sure why this is? If any one can hepo it'd be much appreciated.

[Mark H]

Who told you you need four ground lines - why not ask them why?

In many situations it may well be preferable to have multiple ground connections/wires (reasons such as sheilding, and avoiding voltage drops, etc) - but things will often still work with just a single ground connection between the DAQ device and the test unit. Sometimes you will find things work even without any direct ground connection, as there is often a connection present through the mains supply/power supply route, but you shouldn't really rely on this.    

[MarkLe]

Hi,

What kind of experiment board are you using? What signals does it need or generate, and what kind of Ground connections does it have for connections between it and the 6008?

You should only need one Ground line between the 6008 and other equipment, but if you're using different types of signals it's generally good practice to have one Ground for each type of signal at least (and for maximum noise shielding for low level signals it can be a good idea to have one Ground connection per analogue line, on screen cable if possible).

Hope this helps!

Mark

[willist2]

Hi, I found out that the board I'm connecting the DAQ to (Via a 2xso header) has four ground lines, so for maximum safety/reassurance, these should be kept. Thanks for your help though guys!