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install the dumb mode jumper and then cycle power on the modem. It will then be in dumb mode. If it
becomes necessary to reconfigure the modem, remove the dumb mode jumper and cycle power on the
modem. It will then be in command mode.
LEASED LINE OPERATION
All modems are factory configured to operate on 2 -wire dial and 2 -wire leased circuits. If you are configuring
a modem for 2 -wire leased line operation, please disregard the following paragraph on setting jumpers for 4 -
wire operation and proceed to the standard setup paragraph.
SETTING JUMPERS FOR 4-WIRE OPERATION – If your modem is equipped with the optional 4-wire
interface, you must change one internal jumper to enable 4-wire operation. Once this jumper has been
changed, the modem will not operate on 2 -wire dial or leased circuits. To change the jumper setting, remove
the 2 screws in the modem case bottom and remove the upper half of the modem case. Hold the modem so
that the LEDs a re facing toward you and the connectors are facing away from you. Locate J7 on the left side
of the modem board. You will find that the 2 right pins of this 3 pin jumper are connected together with a
removable shunt. Remove the shunt and place it over the 2 left pins of this 3 pin header. The modem is now
in 4-wire mode and you may proceed to the standard setup paragraph that follows.
STANDARD SETUP FOR 2 AND 4-WIRE LEASED LINE OPERATION – In leased line mode, you may
configure the modem to operate with either asynchronous or synchronous DTE. In order to configure the
modem for leased line operation, it is necessary to use the following commands in your configuration string:
Originate End:
&L1\H1\F1s7=200[
user specific parameters
]&W
Answer End:
&L1\H1\F0s7=25[
user specific parameters
]&W
In the user specific section of each command string, commands may be entered to match the modem to the
specific requirements of the attached DTE. Parameters such as synchronous operation, asynchronous
operation, error correction, compression and flow control may be defined here. Once the modems have
been configured, they must be placed in dumb mode and power must then be cycled.
ADJUSTING TRANSMIT POWER FOR LEASED LINE OPERATION – It is possible to adjust transmit power
on all leased line models; however, improper adjustment could result in extremely poor performance. Please
contact our technical support group if you feel adjustments are necessary for your application.
REMOTE CONFIGURATION
Modems equipped with the remote configuration option offer several commands that enable a remote user to
completely manage and configure them. You may dial into a modem that has remote configuration enabled
and enter online command mode on that device by typing a standard 3 character escape sequence. Once
the remote modem enters online command mode, any valid AT command may be used to review or change
the configuration of the remote device. It is recommended that a unique escape character be set in S
register 2 of devices with remote configuration enabled. Otherwise, the local modem and remote modem will
both enter online command mode when the escape sequence is entered. For this reason, all modems with
the remote configuration option, set S register 2 to a default value of 126, which is the ASCII character tilde
(~).
The remote configuration option also provides several commands to set DTE speed and character format.
