Plasma table 2m x 1m

[Robin Hewitt]

Bit of a delay designing the circuitry. Decided the best place for the CPU was at the cutting head. Close connects for the Y and Z axis controls and switches. Reasonably close connects for the X axis stepper controls and end stop.

Decided to use fibre optic links for the computer connection so I don't have to worrry about interference from the torch.

The Z axis is screw driven by a zippy 24 volt DC motor with brake and 4 bit control on the speed.

The motor has a chopper disc to show where it is.. Rather than waste cpu time oversampling to read the chopper I decided to put it on an interrupt. Here's my cicuit. If either chopper optic changes the the cpu interrupt goes low until I read the data on the input pins.

I'll let you know if it works