RS232 Serial Port, Sub-D 9-pin Connector

RS232 Serial Port

The modem supports a standard RS232 serial interface (EIA/TIA 574) via its 9 pin Sub-D connector, shown below.

Link the GM29 to a microcontroller or computer in the host application, via the RS232 serial port. AT commands are used by the host-application software to communicate with the GM29.

Sub-D 9-pin Connector
	6	7	8	9
1	2	3	4	5

1	DCD	4	DTR	7	RTS
2	RD	5	GND	8	CTS
3	TD	6	DSR	9	RI

Signal	Voltage	Description
	levels

DCD	> +4 V	Data carrier detect
	< –4 V

RD	> +4 V	Received data
	< –4 V

TD	> 2V	Transmitted data
	< 0.8V

DTR	> 2V	Data terminal ready
	< 0.8V

GND	0 V	ground connection

DSR	> +4 V	Data set ready
	< –4 V

RTS	> 2V	Request to send
	< 0.8V

CTS	> +4 V	Clear to send
	< –4 V

RI	> +4 V	Ring indicator
	< –4 V

8 Electrical Connections