What button is used to change coordinates to jog in JOINT mode?

The COORD button is essential for switching the coordinate system in which the robot operates. When you want to jog a FANUC robot in JOINT mode, using the COORD button facilitates the necessary transition to this instruction mode, allowing control over each individual joint of the robot arm.

In JOINT mode, the robot's movements are defined in terms of the angles of its joints rather than Cartesian coordinates (X, Y, Z positions). This is crucial for tasks where precision in joint positioning is required, enabling smoother and more controlled motions.

The other options, while related to robot operation, do not specifically address the task of changing the coordinate system for jogging in JOINT mode. The MODE button typically allows users to switch between different operational modes but does not directly facilitate changing coordinates. The SET button is often used for adjustments or confirmations, but it does not serve the specific function of changing the coordinate mode. The JOINT option refers to the mode itself, rather than a command for adjustment. Therefore, the COORD button is the correct choice in this context.