Quote Originally Posted by JAZZCNC View Post
Yes works exactly like this.

M6 in G-code tells mach to turn on output #? and wait until input #? goes high or low then carry on with Job. The PLC is programmed to do the tool change when it sees Mach's output on it's input. Then when finished turn on it's Output which mach see's on it's Input. The shows goes on.!

Common for ATC's to use PLC for tool change. That said for ATC's which don't require massive amounts of I/O Macro works just as well. The Cslabs as plenty of I/O and don't think this ATC needs lots of I/O so don't see the point my self.

I think the guy who used the PLC will have done so because he didn't have enough I/O. This is one reason why the Cslabs are so good for retrofits because they come with plenty of I/O and can easily be increased without costing the earth.
Wait, i just checked the price of said PLC is just 125$. And has additional IO boards for 45$. Even a motion controller 250 khz for 100$ more. So it seems for less than 300$ one could combine the cheapest Chinese controller i was testing with that PLC and retrofit a mill with ATC! That is great to know.
By the way i found the way to stop and tool change in that controller