ADTRAN 12804108L1A, Системное руководство

Страница: 30 / 60

Section 3 Engineering Guidelines TRACER 4108/4208 System Manual
30 © 2003 ADTRAN, Inc. 612804208L1-1B
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
AUTO ANSWER
and
9600
BPS
.
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
ODEM
C
ONNECTION
is selected in the menu system, the TRACER 4108/4208 will de-assert DTR
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
M
ODEM
C
ONNECTION
resets the TRACER 4108/4208 to the password entry
screen.
Table 5 contains the wiring diagram needed for connecting the TRACER 4108/4208 RS-232 interface to a
modem using the null modem adapter.
Hangup-on-DTR-drop may need to be explicitly enabled on some modems.
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 NAME PIN NAME
2 TX 3 RX
3 RX 2 TX
4 RTS 5 CTS
5 CTS 4 RTS
6 DSR 20 DTR
7 GND 7 GND
8 CD 8 CD