SENA STS Series - Manual (Page 61)

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4.2.10. Modem Configuration
The STS Series supports direct modem connection to the serial port of it. When user wants to connect
modem to a serial port, he must configure Modem init-string and DCD behavior on modem
configuration page. The STS Series supports modem connection only when host mode is set as TCP
mode.
 Enable/Disable modem
By enabling this menu, user can attach a modem directly to the serial port of STS Series. If this
parameter is enabled, STS Series considers this port will be used for modem use exclusively.
 Modem init-string
User can specify modem initialization string for his modem in Modem init-string parameter. When a
serial port is set as modem mode by setting Enable/Disable modem parameter as Enabled, STS
Series sends modem initialization string to the serial port whenever rising edge of DTR pin is detected
or parameter related with serial port configuration is changed.
 DCD behavior
If DCD behavior is set as Allow TCP connection only by HIGH, STS Series permits a connection from
the remote host only when the DCD status of serial port is high. This feature is useful when user want
to use a serial port only for dial-in modem mode. In this case, if there is no connection through modem
already, STS Series dose not permit TCP side connection.
 Automatic release modem connection
If Automatic release modem connection is set as Enable, modem connection will be closed by STS
Series if all TCP connections are closed once at least one TCP connection is opened. If this option is
set as Disable, modem connection will not be closed by STS series even if all TCP connections are
closed. Please note that actual phone line connection will be closed if one of modems closes
connection, regardless of this option. That is, this option can be used for STS Series to disconnect
modem connection by itself when all TCP connections are closed.
If user wants to use dial-out function, he should set DCD behavior as None because he must be able
to access modem connected to a serial port to send dial out command to the modem first.