User guide

USR4204 User Guide
Page 15 of 69
Local Echo - Disabled
If available, disable Local Echo to prevent USR4204 transmissions from recirculating
between the modem and the USR4204.
Auto-Answer - Enabled
Auto-Answer does not apply to cellular modems, however the recommended setup for
cellular out-of-band remote management does require the modem to connect whenever
contact is initiated by the management terminal.
Carrier Detect Signal - Active
If available, the RS-232 Carrier Detect signal should be active (not overridden) so the
USR4204 will automatically present its Main Menu upon connection and automatically close
ports upon disconnection.
Error Correction - Enabled
Error Correction does not apply to cellular modems. The TCP/IP protocol handles flow
control messages transparently.
Xon/Xoff Flow Control- Enabled
Enable Xon/Xoff flow control in the modem if the USR4204 has flow control enabled.
Enable Xon/Xoff flow control in the USR4204 and in the modem to prevent
buffer overflow for any of these situations:
 The equipment being managed through the USR4204 uses serial
rates different from 9600bps
 USR4204 batch configuration files are larger than 1500 characters
 USR4204 linefeed pacing is enabled
AT Commands - Disabled (a.k.a. “Dumb Mode”)
The Dumb Mode requirement does not apply to cellular modems because a key-press
cannot abort a cellular connection.
Cabling the Cellular Modem
Once the cellular modem has been properly configured, it may be attached to the USR4204
terminal port.
Modem Connector
Adaptors and Cables Needed
DB25F
Provided DB25 Adapter and provided RJ45 rollover cable.
DB9F
Select one of the following:
 Purchase a RJ45-to-DB9M null modem adaptor and use
the provided RJ45 rollover cable.
 Purchase a RJ45-to-DB9M adaptor and use a straight
Ethernet cable.
 Purchase a DB25F-to-DB9M adaptor and use the
provided RJ45-to-DB25M adaptor and RJ45 rollover
cable.
 See appendix A for the wiring diagrams for all options.