Mounting and Installation
© Siemens AG 2002 All Rights Reserved 6NH7811-0AA22
MD2 Modem (07/2002)
2-5
2.1.4 Pin Assignments for the RS232 and RS485 Ports
The X1 connector is a 9-pin Sub-D miniature socket (male). The following table
lists the pin assignments. Used as an RS232 interface the pin assignment
corresponds to a standard PC port.
The RS232 port is activated with a 4-pin DIL switch which can be accessed from
below through the housing grill. The corresponding settings on the DIL switch can
be seen in Fig. 2-6.
Table 2-2 Pin assignments on X1 RS232 socket
Diagram Pin no. Signal
name
Signal
direction
Comments
1 DCD Output
2 RXD Output
3 TXD Input
4 DTR Input
5GND
6 DSR Output
7 RTS Input
8 CTS Output
15
69
9 RI / T Output
The RS485 port is a 9-pin Sub-D miniature socket (female). The following table
lists the pin assignments.
The RS485 port and terminating resistor can be activated with a 4-pin DIL switch
which can be accessed from below through the housing grill. The corresponding
settings on the DIL switch can be seen in Fig. 2-6.
Table 2-3 Pin assignments on the X2 RS485 socket
Diagram Pin no. Signal
name
Signal
direction
Comments
1
2
3 Data B bi-directional
4
5M5-
0 V for bus termination in the plug *)
6P5-
5 V for bus termination in the plug *)
7
8 Data A bi-directional
54321
9876
9
*) It is recommended to activate the terminating resistor for the RS485 bus in the plug and not in the
modem itself. The recommended RS485 setting in the modem is shown in Fig. 2-6.
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