Air Brakes and Train Handling Rules - Alaska Railroad

68 EOT Telemetry Devices68.8.6 Checking the Operation of the LCUThe LCU does not have an ON/OFF switch. Instead, the LCUautomatically turns on whenever the primary power source is turnedon.When the LCU turns on, it functions as follows:1. The display beeps and shows [DIGITAIR] for 1 second.2. The display shows [6622-A1] for 1 second.• “6622” is the LCU’s model number.• “A1” is the LCU’s software version number.3. The LCU turns on all segments of all digits of the display. If anysegment is not on, replace the LCU.a. The LCU keeps all segments on until it receives a reportfrom the EOT unit.b. If the LCU does not receive a report or receives a report withthe wrong ID number, the LCU keeps all segments on. Inthis state, the LCU will not display messages or alarms fromthe EOT unit (see Rule 68.8.3A).68.8.7 Reading the LCU DisplayDuring normal operation, the LCU displays its normal pressuredisplay. However, under certain conditions, the LCU will displayalarm messages (either steady or flashing) and will sound alarmbeeps. The following sections describe the No Communicationsalarm message and other LCU display messages.A. No Communications Alarm Message [NO COM]The [NO COM] alarm message indicates that the LCU and EOT unitare not communicating. The [NO COM] message is displayed asfollows:1. The LCU gives a [NO COM] alarm if it does not receive a reportfrom the selected EOT unit for a period of 196 seconds.68-30 ARRC Air Brakes and Train Handling Manual June 1, 1996