Lantronix MSS4 - Page 35

Configuration Serial Port Configuration
4-11
Note: Modem Emulation Mode, in which the MSS acts like a modem and only accepts AT modem
commands, is discussed in
Chapter 5.
After configuring modem-related settings, refer to the
Modem Configuration Checklist on page B-4.
Modem Control
When enabled, this feature allows the MSS to check for signals coming from the modem (or other attached
serial device) to establish whether a valid connection exists. If a connection has ended, the MSS should be
able to log out the port and prepare to accept a new connection. Similarly, if no connection is open, the MSS
should know to ignore spurious characters from the port and only accept valid connection attempts. The
MSS can do both of these when modem control is enabled.
Modem control implies three things:
 The MSS will log out the port when DSR is dropped (as if DSRLogout were enabled).
 The MSS will hold DTR low for approximately 3 seconds after the port is logged out.
 The MSS will not Autostart a new connection until the attached device asserts DSR.
To enable modem control for a serial port, enter the Change Port [Portlist] Modem Control command.
The following example enables modem control for all four serial ports.
Figure 4-26: Enabling Modem Control
Signal Checking
When signal checking is enabled, the MSS will check for the presence of an asserted Data Signal Ready
(DSR) input signal before allowing incoming network connections to the enabled serial port. Network
connections to the serial port will not be permitted unless the DSR signal is asserted.
To enable DSR signal checking, use the Change Port [Portlist] Signal Check command. The following
example enables signal checking for the first serial port.
Figure 4-27: Enabling Signal Checking
DSRLogout
Note: DSRLogout is not available in RS-485 mode.
When a device connected to the MSS is disconnected or powered off, the DSR signal is
de-asserted. The MSS can be configured to automatically log out the port when this occurs using the
Change Port [Portlist] DSRLogout Enabled command. This also prevents users from accessing other
sessions by switching physical terminal lines. The following example enables DSRLogout for the first serial
port.
Figure 4-28: Enabling DSRLogout
Local>> CHANGE PORT 1-4 MODEM CONTROL ENABLED
Local>> CHANGE PORT 1 SIGNAL CHECK ENABLED
Local>> CHANGE PORT 1 DSRLOGOUT ENABLED