PIN Function Description
19 GROUND Ground
20 IGNITION Connecting this pin to the ignition line of the vehicle will automati-
cally turn on the radio if ignition of the vehicle is turned on.
21 ON_OFF_GND This is the On/Off control for the old Control Head “J” (MTM300
Control Head)
22 EXPANSION_PTT Expansion PTT, works together with INT_MIC
23 Not Connected NC
24 HANDSET_AUDIO Handset audio to earpiece impedance has to be > 200 Ohm
25 Not Connected NC
5.4.3
9-Pin subD Connector
The pin assignment of this 9-pin subD connector follows the requirements of an RS232 standard
interface with the RS232 voltage level. The cable (see section “Connecting Cables”) which has to be
used is a standardized serial interface cable which allows to connect a data device with an RS232
Interface such as PC, Laptop, Console.
Table 53: 9–Pin subD Connector Pins
Pin Function Description PC Direction
1 DCD Data Carrier Detect Input
2 RXD Received Data Serial Serial IN
3 TXD Transmitted Data Serial OUT
4 DTR Data Terminal Ready Output
5 GND Ground Output Output
6 DSR Data Set Ready Input
7 RTS Request to Send Output
8 CTS Clear to Send Input
9 RI Ring Indicator Input
68015000181-LB
Chapter 5: Connectors and PIN Assignment
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