What must each signal or signal-sequence be configured to in a rack?

The correct understanding revolves around the architecture of control systems in robotics, specifically in the context of FANUC robots. Each signal or signal-sequence in a rack must be configured to a specific slot and channel number. This configuration is crucial because it allows the control system to properly identify and communicate with various I/O devices connected to the rack.

In a typical setup, the slot refers to the physical location in the rack where a module or device is installed, while the channel number designates the specific input or output line associated with that slot. This level of granularity is necessary for the controller to route signals accurately and ensures that data is exchanged correctly between the robot controller and the inputs/outputs.

Understanding this configuration is fundamental for troubleshooting and for setting up communication pathways within the system, as each signal's identification through its unique slot-channel pairing allows for a structured approach to control and monitoring of the robotic operations.