Hi,
Mach Motion is a company, separate from NFS/Artsoft that make motion control products, including full machines. They have over the years contributed a number of important ideas, code,
plugins etc to the Mach community. For instance the Lathe Wizards found in Mach4 are Mach Motion code, and note that only the compiled code is available, Mach Motion quite rightly
hold the source code for themselves.
Mach has a whole bunch of signals, some like mc.OSIG_PTRSF, is an output signal, mc.ISIG_PROBE is an input signal....but there are many hundreds more, many of which are not documented and are for signalling between
Machs different modules and plugins which are neither inputs nor outputs but event signals between components.
In Mach4Hobby/Docs/MachCoreAPI.chm under the Mach Signals you will find a list of all the input signals ( mc.ISIG_*********) and output signals (mc.OSIG_*********) available for use by users.
I have attached a pic of the Edit Screen page. You will note that I have just plonked an LED, called led108, you can see it in the file tree and its representation in Spindle block, it was a convenient open space.
Note also that I have attached the LED to reflect the state of the Parts Finished output signal. Easy.
Now you can run some parts and see what happens to that LED. This should inform your decision as to whether it is an appropriate signal for your purposes.
Craig