What message is displayed on the HTD when the TEST button on the ETD is pressed?

When the TEST button on the Electronic Train Device (ETD) is pressed, the message displayed on the Head-of-Train Device (HTD) is "ARM NOW." This indicates that the system is in the process of preparing for the air brake application, confirming that the device is ready to transition from the test mode to a fully operational state.

The "ARM NOW" message signifies that the ETD has successfully completed its initialization checks and is now awaiting further actions to engage the train's braking system. This is an important step for the crew, as it ensures that the ETD is functioning properly before proceeding with any movements.

While other messages might be relevant to different stages of the ETD's operation or indications of status, "ARM NOW" specifically alerts the crew to the next action required to ensure the train's braking systems are active and functioning as intended.