Lantronix ETS Reference Manual - 5.2.3 Baud Rates
Modems
Ports
5-8
5.2.2.1 DSR (Data Set Ready) for Automatic Logouts
An ETS port can be configured to automatically log itself out when DSR is no longer asserted; in other
words, the port logs out when the modem is disconnected. This can help ensure port security because users
are prevented from unplugging terminal lines and using sessions that are still active.
5.2.2.2 DSR for Controlling Remote Logins
The DSR signal can also be used to determine whether or not a remote login to a port will be permitted.
DSRlogout can be used to automatically log a port out when the DSR signal is deasserted. See DSRlogout
on page 5-16 for more information.
The Signal Check characteristic requires the assertion of the DSR signal before a remote login is permitted
on a particular port. Signal Check is generally enabled for use with printers; if the printer doesn’t assert the
DSR signal, it’s assumed to be disconnected or powered off. In this case, the remote login isn’t permitted,
and print jobs are not sent from the ETS to the printer. See Preventing Access Until DSR Is Asserted on page
5-15 for more information.
5.2.2.3 DCD (Data Carrier Detect)
The DCD signal is asserted by the local modem when it detects a connection from a remote modem. If
you’re using a DB25 port, no wiring is required in order to use the DCD signal.
RJ45 ports have one pin that can be used for either DSR or DCD. If you are using modems, this pin must
be wired to the modem’s DCD pin. If you are using another type of device (such as a terminal or printer),
this pin should be wired to the device’s DSR pin. Refer to the Pinouts appendix of your Installation Guide
for instructions.
5.2.2.4 DTR (Data Terminal Ready)
The ETS asserts DTR when it is ready to accept incoming data or connections. It also uses DTR to cycle the
modem when modem control is enabled by temporarily dropping the signal.
ETS ports can be configured to assert DTR only when a user logs into the port by enabling the DTRWait
characteristic. See DTRwait on page 5-12 for more information.
5.2.3 Baud Rates
The ETS and modem must agree on the baud rate used for the serial interface. However, the modem attached
to the ETS may be communicating with the remote modem at a different speed due to the use of compression
and error correction techniques. The ETS and modem can be configured in one of three basic ways:
1
Set the baud rate of the ETS and the modem to the highest expected rate, disable autobaud on the ETS
and on the modem, and use flow control to handle connections at all slower rates.
On some modems disabling Autobaud is known as “locking the serial speed” or “locking the DTE
speed.” This method allows nonstandard transmission rates such as those found in V.32bis (14,400
baud), error correction, and data compression. This method is generally the most reliable as the
modem and the ETS always use the same baud rate.