Compaq 281862-002 User Manual page 101

7-10 Direct Connections
Flow Control — Configure each port on the terminal server for
hardware flow control. If the receive and transmit functions are each
configurable, make sure they are both set for hardware flow control. An
improper flow control setting could result in the loss of characters,
causing the remote terminal to display incomplete or garbled
information.
DTR Control — This setting is crucial to the operation of the Integrated
Remote Console. The terminal server must be programmed to assert
DTR whenever a communication (TELNET) session is open on the
selected serial port. Integrated Remote Console uses the DCD control
signal (which is driven by the terminal server's DTR output) to
determine whether a remote session is open. Integrated Remote Console
ignores any serial port activity whenever DCD is inactive.
Consequently, if the terminal server does not assert it's DTR output, it is
impossible to establish a connection with Integrated Remote Console.
Conversely, if the terminal server always asserts DTR, IRC always
thinks a remote session is being requested, which could result in a slight
performance penalty on the managed server. In addition, IRC does not
automatically log out a user whenever the communication port is closed.
For proper operation of IRC, the DTR output of the terminal server must
be asserted whenever a communication session is opened, and removed
whenever a communication session is closed.