MoTeC Global Forum

Hello all,

I tend to use a few different industrial sensors that have the standard, Power, Signal & Ground wires. Frequently, however, they require the use of a Sensor or Signal ground. Is there a pin that is recommended for this use, or is it the standard channel ground that should be utilized?

I find that the channel grounds are common to the power ground in the harness. However, I would like to know if there is a pin specific to this type of ground that you recommend.

Thanks.

Peter

In electronics there is a concept called single-ended, which is a signal wire that stands alone and is referenced from a stable "ground".
Think of your stereo - which has a left and right channel and the co-axial cable is single ended (even though the ground surrounds the single ended wire.
For microphones, often there are 2 wires plus the ground, which are referred to as a twisted pair. And these are almost always twisted the same way that a ethernet cables or CAN-bus wires are twisted.

If your sensor is like these, then the "signal" ground is one of the two twisted-pair wires.

For sensors with a low output impedance there is little need to have them as a twisted pair, so you only need to run one wire.
But even though you might be using the chassis as a ground, you will still get less noise on the signal-wire of you twist a ground wire around the signal-wire and terminate it to ground on each end, and it is easier to twist the wires together and run them that way from the start rather than later figure out that you might want to twist them...

So if the sensor has a specific signal ground, then you need to use a differential input on the motec end.
I think that a VIM has some differential inputs.