The Z tool offset sensor is a fixed position on the machine frame where all tool are referenced to. Each tool in turn is touched of the reference sensor so the software knows the specific offset of each tool. This allows the software to always have the correct Z zero point for each tool during an actual toolpath. By touching each tool off this common datum the software knows automatically how to apply a tools Z zero refernce in auto mode.
The Z workpiece pen sensor allows automatic setting of the Z reference plane once all the tools are set up. This system can be a manual pull down and button press system. Or it can be a fully pneumatic driven piston auto push down and Z set.