Hi,
Am I correct in reading that Mach4 is not able to support Up/Down signals from an external monitor?
Not quite, Mach4 has defined THC signals like THC_UP and THC_DOWN but it doesn't do anything with them. They are meant to be passed to the external controller plugin
and then to the controller board, in your case the UC100. Unfortunately the UC100 cant do anything with them.
CNCDrive, the company that makes the UC100 and its bigger brother the UC300 have only had a Mach4 plugin for about a year. It has not yet seen the development
of features that some of its more mature competition including THC. To give CNCDrive credit though their Mach4 plugin has proven to be remarkably reliable and trouble
free even if it doesn't have many controller only realtime features.
Craig