Quote Originally Posted by Neale View Post
Did you consider use of a safety relay? I managed to pick up one cheap on eBay, partly because it lets me switch a number of circuits from the e-stop switch, convenient way to configure "momentary contact" standby switch, etc. Does your e-stop connect to a latching relay or similar?
Technically to meet the latest regs, I should use a proper E-stop relay, however it's something I've not bothered with yet, and as I'll be the only person using the machine, I technically don't need to conform to any regulations.
However, the main reason is I'd need to add an enable button, and the control panel is still a sketch in a notepad at the moment. It's something I will likely add at a later date, once I have fully functional control panel.
The real benefit of a E-stop relay is the contact monitoring, whereby should a contact stick/weld shut, it won't enable.

You mention limit switch triggering as equivalent to e-stop. I can see why you might want to do this, but will it give problems in separating limit and home switch operation? I use drive fault from my digital drives to trigger e-stop but limit/home switches go direct to CSMIO (similar argument to yours re dedicated firmware - no PC involvement).
I always use separate home switches, so homing is not a problem. I personally think it's a waste of inputs wiring the limits directly to the controller, as there is little benefit. If you can't tell what switch you've just ran into, you're doing something wrong!
What I do have though, is all the limit switches and everything else in the E-stop circuit, pass through a row of DIN rail terminal blocks, so should something fail, 30 seconds with a multimeter lets me know where the problem is. I do take the Drive fault signals to the controller, as it lets me know what drive has failed, for the reason I need to turn the cabinet power of before I can open the cabinet at which point the drives get reset.

As always, there are several ways to achieve this. The main thing to consider with any system, is what would happen in the worst case scenario, should any/multiple parts of the system fail.