PCNC770 LED Safety Column for AUTO/MANUAL Switch

In the 9 years I have had the 770 Series 3 there is one thing that has always bugged me about the hardware controller design. I do a lot of switching from AUTO to MANUAL and back. I also am left handed so that the monitor/keyboard arm is on the left of the machine and the motor column blocks much of the control panel in my normal machining position.

There is no indicator on the panel other than the black AUTO/MAN switch to tell the mode. This switch is NOT conveyed to the PathPilot controller and the controller has no idea that the hardware may be set to Manual. You can start a program or turn on the spindle with PP and it will happily begin motion or indicate the tool is spinning, but it will be dead still! I have crashed my share of tools in this way.

While there are a few parameters within PP that are available and intended to indicate the state of such an AUTO/MAN mode that could be used in a python plug-in to control PP behavior, they are not active. The best I could eventually come up with was to add a safety warning LED column (see pictures) on the left-hand side of the spindle column that would clearly indicate the hardware controller state. The first picture shows the LED column YELLOW=MANUAL and RED=SPINDLE-MOTOR-ON, while the second picture shows the spindle off and GREEN=AUTO mode.

A more detailed description can be found here:
AUTO/MAN LED Column Details

I build a small control panel that taps, buffers and optically isolates the state of the AUTO/MAN switch and spindle logic from the Emerson Commander SK VFD. (See the following figure.)

I used hardware I had on-hand, so the circuit is a bit more clunky than a custom design needs to be. But it is absolutely necessary to buffer and isolate the AUTO/MAN switch because it is internal to the Tormach control PCB and undocumented. The mechanical relay PCB is from MPJA, and allows for a light column powered by low or high voltage. The small SMPS is 12VDC 1A extracted from an old wall-wart.

Now I just have to learn to pay attention to the LED lamp signals and I will save a few tools!