Rs-232 Connection (Modem Use) - ADTRAN 12804108L1A System Manual

Section 3 Engineering Guidelines

RS-232 Connection (Modem Use)

Modem controls, discussed in Section 5, User Interface Guide, enable or disable modem control
through the RS-232 interface. When this option is enabled from a standard terminal connection, all
RS-232 communications cease until a modem with a null modem adapter is attached between the
TRACER 4108/4208 and the data modem. Configure the data modem for
When the user connects via the modem to the TRACER 4108/4208 unit, communications via the RS-232
port resume. If a user accidentally enables modem control from a terminal and disrupts the RS-232
communication, pressing <Ctrl + Z> three times will temporarily disable the modem control option (until
the system is reset) and will access the system option to disable modem control.
The TRACER 4108/4208 must be interfaced to a modem via an RS-232 null modem adapter or cable. The
null modem converts Clear To Send (CTS) and Data Set Ready (DSR) into Ready To Send (RTS) and Data
Terminal Ready (DTR), respectively. These signals indicate (to most modems) that a valid DTE terminal
device is present. The null modem interface must route Carrier Detect (CD) on pin 8 directly from the
modem. When using the RS-232 interface for modem control, the modem must source CD only when
actually connected to a carrier.
When
M C
ODEM ONNECTION
and DSR for a time greater than 20 msec. The null modem consequently drops DTR and RTS at the
modem interface, signaling the modem to hang up the line. If password functionality is enabled in the
TRACER 4108/4208, selecting
screen.
Hangup-on-DTR-drop may need to be explicitly enabled on some modems.
Table 5 contains the wiring diagram needed for connecting the TRACER 4108/4208 RS-232 interface to a
modem using the null modem adapter.
The null modem interface must route Carrier Detect (CD) on pin 8 directly from the
modem. When using the RS-232 interface for modem control, the modem must source CD
only when actually connected to a carrier.
Table 5. TRACER 4108/4208 (DCE) to Modem (DCE - DB-25)
PIN
2
3
4
5
6
7
8
30
is selected in the menu system, the TRACER 4108/4208 will de-assert DTR
M C
ODEM ONNECTION
NAME
TX
RX
RTS
CTS
DSR
GND
CD
© 2003 ADTRAN, Inc.
TRACER 4108/4208 System Manual
AUTO ANSWER
resets the TRACER 4108/4208 to the password entry
PIN
3
2
5
4
20
7
8
and
9600
BPS
NAME
RX
TX
CTS
RTS
DTR
GND
CD
612804208L1-1B
.