TRACER 5045 System Manual Section 3 Engineering Guidelines
612805045L1-1A © 2003 ADTRAN, Inc. 29
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 5045
and the data modem. Configure the data modem for
AUTO ANSWER and 9600 BPS. When the user
connects via the modem to the TRACER 5045 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 configuration to disable modem control.
The TRACER 5045 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
MODEM CONNECTION is selected in the menu system, the TRACER 5045 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
5045, selecting
MODEM CONNECTION resets the TRACER 5045 to the password entry screen.
Table 3. TRACER 5045 (DCE) to Terminal (DTE) Diagram (DB-25)
PIN NAME PIN NAME
2 TX 2 TX
3 RX 3 RX
4 RTS 4 RTS
5 CTS 5 CTS
6 DSR 6 DSR
7 GND 7 GND
Table 4. TRACER 5045 (DCE) to Personal Computer (DB-9)
PIN NAME PIN NAME
2 TX 2 TX
3 RX 3 RX
4 RTS 7 RTS
5 CTS 8 CTS
6 DSR 6 DSR
7 GND 5 GND
Hangup-on-DTR-drop may need to be explicitly enabled on some modems.
