Mounting and Installation
6NH7811-0AA22 © Siemens AG 2002 All Rights Reserved
2-12 MD2 Modem (07/2002)
Note
The 1200 and 2400 bps transmission speed is suitable for lines with band widths
limited to the normal voice frequency band (300 Hz – 3400 Hz). This is typically
the case for leased lines from public telephone companies. A corresponding
certification from the German Telekom is available for the MD2 modem. It is
entitled, 'Connection to a transmission line with analog connection points (2-wire)
and 3.1 kHz effective band width (300 Hz – 3400 Hz)'. See Chapter 1.5.
Setting the Operating Mode
In addition to the settings for the dedicated line, the operating mode of the modem
needs to be specified. This involves setting the operating mode for an RS232 or
RS485 interface, the repeater mode or a test mode to help in the installation. The
operating modes are set on switches 1 to 4 of the 10-pin DIL switch.
The procedure is as follows:
Switch off the power supply of the modem and make the desired settings using the
DIL switch. When the power is switched on the selected operating mode settings
become active.
Table 2-11 Settings on the 10-pin DIL switch (operating mode)
Setting on
DIL Switch
Meaning
1234
OFF
ON
5678910
Normal operating mode
This mode must be selected when the MD2 is connected through its
RS232 interface to a terminal.
1234
OFF
ON
5
6789
10
Normal operating mode with DTR/RTS on
Set this operating mode if you want to connect the MD2 via the RS232
interface to a terminal that does not have control signals (DTR and
RTS). This operating mode is only suitable for 4-wire lines in a point-
to-point network configuration.
1234
OFF
ON
5678910
Repeater
This mode must be selected when two MD2s are connected to
function as a repeater.
1234
OFF
ON
5678910
with RS485 interface
This mode must be selected when the MD2 is connected through its
RS485 interface to a terminal or another MD2.
1234
OFF
ON
5
6789
10
Signal refresh off
In this operating mode the receive signal is not refreshed. In this case
the RS485 interface cannot be used.
Using this operating mode allows data to be sent with < 1200 bps.
1234
OFF
ON
5
6789
10
Test mode: Test f
H
constant
In this test mode the upper keying frequency is continuously present
at the modem transmitter output.
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