Thanks for the advise, Jazz. Keep in mind we rely on computers for safety all the time, in fact in some cases we use computers to make mechanical things safer :-) I do not really agree with you comparing an arduino with a pc as they are worlds apart in terms of complexity and things that can go wrong etc but its not a topic I want to labour.

I believe what you are trying to get across is that the relay solution is ultimately more reliable and I'd still like to get that working if possible. I thought this was going to simple as pie and its not like I did not try and I spent more than a full day to get it working and failed to do so reliably. My challenge is the following: Fault output on the driver is a sinking type output. I connected it as per the manual with a simple little 5V circuit containing only a current limiting resistor and I got 0.7V on the driver fault output pin when in fault and 4.7V when not. I can swap these around in the driver setup when I set fault to "active high". I used this setup with a small relay board that basically contains a transistor and a diode but it switches even at 0.7V and its at that point where I started fiddling and burning time and eventually chucked in favor of the simple arduino setup which I got working in 30mins. So what's the right way to do this? Can you perhaps please help me out with a description or diagram or close-up pick of your fault signal setup if you are using Leadshine drivers?