What mode switch position allows you to send the machine to its reference (home) position?

The position labeled as zero return is specifically designed for moving the CNC machine to its reference or home position. When the machine is in this mode, it initiates a process that allows the axes to return to a predefined starting point, often referred to as the home position. This is essential for ensuring accurate positioning in subsequent operations and for maintaining repeatability across multiple machining sessions. The zero return function typically includes limit switches that stop the machine at the home position for safety and accuracy.

The other choices involve specific commands or functionalities that do not pertain to returning the machine to its home position. For instance, the line related to facing or arc commands deals with tool movements or operations but does not facilitate returning to the home position. Similarly, canceling compensation or turning off coolant does not involve moving the machine's axes to their reference points. Therefore, zero return is the specific function needed to achieve the desired action of homing the machine.