Before linking the RCT to the locomotive, which button must be held until "Link primary RCT" is displayed?

Holding the no/function button until "Link primary RCT" is displayed is a critical step in the linking process of the Remote Control Terminal (RCT) to the locomotive. This action is essential because it ensures the system is prepared and is actively looking to establish a connection. The no/function button's purpose is to prevent any unintentional commands from being executed during the linking process, allowing for a safe and controlled setup.

The correct operation involves first preparing the RCT by holding the no/function button, which signals that the operator is ready to perform the linking action safely. Once the system recognizes this input, it displays the message prompting further actions, confirming that the device is set for linking to the locomotive.

In the context of remote control operation, adhering to this protocol helps to maintain operational safety and technology integrity by ensuring that the system is in the correct mode before establishing a connection.