HP AlphaServer TS15 Owner's Manual page 183

Through Mode
Through mode is the default operating mode. The RMC routes every character of data
between the internal system COM1 port and the external COM1 port. If a modem is
connected, the data goes to the modem. The RMC filters the data for a specific escape
sequence. If it detects the escape sequence, it enters the RMC CLI.
Figure 6–1 illustrates the data flow in Through mode. The internal system COM1 port is
connected to one port of the DUART chip, and the other port is connected to a 9-pin
external COM1, providing full modem controls. The DUART is controlled by the RMC
microprocessor, which moves characters between the two UART ports. The escape
sequence signals the RMC to enter the CLI. Data issued from the CLI is transmitted
between the RMC microprocessor and the external port.
In Through mode, the RMC also broadcasts power-up and power-down error messages
through the COM1 port. Additional RMC broadcast messages may occur when the RMC
CLI is active.
NOTE: The internal system COM1 port should not be confused with the external COM1
serial port on the back of the system.
Using the Remote Management Console 6-5