Connector Specification

		Connector Specification

Serial (RS232) Interface

External modems are fitted with a 25-way D-type female connector, marked "SERIAL INTERFACE (DTE)". This has the following pin designations:

**RS232 connector pin out**
Pin	Decription	Signal	Direction
1	Protective Ground	N/A	N/A
2	Transmitted Data	TXD	Input
3	Received Data	RXD	Output
4	Request to Send	RTS	Input
5	Clear to Send	CTS	Output
6	Data Set Ready	DSR	Output
7	Signal Ground	GND	N/A
8	Data Carrier Detect	DCD	Output
9	Test Voltage; +9V	N/A	Output
10	Test Voltage; -9V	N/A	Output
15	TX Clock	TXCLK	Output
17	RX Clock	RXCLK	Output
20	Data Terminal Ready	DTR	Input
22	Ring Indicator	RI	Output
24	External Clock	XTCLK	Input

Telephone Connection

The LINE connector on the rear panel of the modem is of the type RJ11. The corresponding plug on the telephone lead supplied with the modem is connected to this socket. The pin configuration is as follows:

The other end of the telephone lead is terminated with a type 431A plug, which should be plugged into a standard British Telecom telephone socket. The pin configuration in this plug is the same as the RJ11 connection.

A telephone handset can be plugged into the socket marked 'TELEPHONE' on the rear panel of the modem.

Speaker connection (voice models only)

The 3.5 mm stereo jack socket on the rear of the modem provides a means of connecting the modems audio output signals to an external speaker or amplifier. It is also possible to connect a set of headphones to this socket although care should be taken to ensure that a low audio level is selected. See description for the L command for more information. When a jack plug is inserted into this socket, the internal speaker is disabled.

Microphone connection (voice models only)

The 3.5 mm stereo jack socket on the rear of the modem provides a means of applying an external audio input to the modem. The socket is suitable for a condenser microphone as a power supply is available on the socket. When a jack plug is inserted into this socket the internal microphone is disabled.

This input is also suitable for direct input from sources other than a microphone. Care should be taken to ensure that the signal level applied does not exceed 50 mV. In most cases the signal requires attenuation before connection to the microphone socket.