Allied Telesis AT-S102 - Manual (Page 30)

Chapter 1: AT-CV5M02 Management Card
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You can monitor the communications between the active management
card and the standby card over the chassis’ backplane by connecting a
personal computer with a terminal emulator program to the Console port
on the standby card. There are Update, Copy, and Heartbeat messages.
Update and Copy messages are sent by the active management card
when updating the master configuration file on the standby card.
Heartbeat messages are generated periodically by the standby card to
check the status of the active card.