Bay Networks 5390 Administering page 144

Modems
To use modem control (DTR/DCD/DSR), set the control_lines parameter to modem_control. The
Model 5390 server asserts DTR when the port is ready for use. It then waits for DCD and DSR to
be asserted before opening the session. After opening the session, any drop of DCD that lasts more
than 400 milliseconds, or any drop of DSR, causes a port reset. A port reset drops DTR for at least
one second and kills any jobs attached to the port.
To use software flow control (XON/XOFF), set control_lines to none, and set both
input_flow_control and output_flow_control to start/stop. The Model 5390 server sends XOFF
when it does not want to receive any more data; it sends XON when it is again ready to receive
data. When the Model 5390 server receives XOFF, it stops sending data to the port; when it receives
XON, it resumes sending data to the port.
To use both EIA/hardware flow control (RTS/CTS) and modem control (DTR/DCD/DSR), set
control_lines to both, and input_flow_control and output_flow_control to eia. The Model 5390
server uses these signals as described in the previous paragraphs.
To use both software flow control (XON/XOFF) and modem control (DTR/DCD/DSR), set
control_lines to modem_control, and input_flow_control and output_flow_control to start/
stop.
When using a modem connected to a slave port, if need_dsr is enabled, the connection fails if no
DSR signal is present. If need_dsr is disabled, the Model 5390 server accepts the connection.
If a port with modem control enabled has need_dsr set to Y, the user cannot make a connection
until DSR is active, but then can communicate out the port even if DCD is not asserted.
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