Logix IO Selection

On a green field project with AB logix IO @ 24 VDC is it best to use sinking or sourcing IO?

I know either will work but what are the opinions on what is best and why?

My preference is Source outputs (24+ on output) and Sink for 24+ on inputs (switching of the 24+).
I don't really like controlling the 24-, I think of it as my neutral.

Here is a nice description:
http://www.automationdirect.com/static/specs/sinksource.pdf

I will be anxious to see what others say.

..

In the USA, sourcing output modules and sinking input modules are by far the most common polarity. The average maintenance guy walking up to a machine will measure 0V on an input point and assume it's OFF.

Unless you have a lot of European sensors that are only available in sinking mode, I would stick with sourcing sensors.

Call your A-B distributor and ask them how many 1756-IB16 modules they have on the shelf, versus how many 1756-IV16 modules. I'll bet they stock more of the 1756-IB16.

it depends

if I have 3 voltage supplies on 3 relays and they all need to be actuated by the same outputs, I would sink the outputs so I could control 12, 24 and 6 volts for example.

This is not usually the case outside of circuit boards.

Most common is sourcing outputs and sinking inputs.

Do what makes the machine work best and then train the people to use the machine.

I am sick of making changes in the machine that reduce fubctionality just because some person doesn't like the way it looks on a diagram.

Hi

90 % plus in Europe we use sinking inputs and source outputs I also think it just makes it easier for trouble shooting as its the way must people would think

Donnchadh