GSM0128IG001
37
Revision Draft – 9/22/08
6.8.7
Serial Interface (9 Pin I/F) (Pins 41, 43, 45, 47, 49, 51, 53, 55, 57)
The modem provides a standard 16550 UART serial interface to the host. The data interface operates at
CMOS level. The Enabler IIG is designed to be used like a DCE device. RxData is the serial data from the
modem to the host. TxData is the serial data from the host to the modem.
Figure 15 - Enabler IIG Serial Interface
This data may contain 7 or 8 data bits, 1 or 2 stop bits, even/odd/no parity bits. The baud rate may be
adjusted to , 300, 600, 1200, 2400, 4800, 7200, 9600, 14400, 19200, 28800, 33900, 38400, 57600, ,115200,
bits per second.
Default settings are 8 data, 1 stop, no parity, and 115200 baud. DTR may be used to force the modem into
AT command mode from online data mode (See AT Command Document, command AT&D). RTS and CTS
may be used for hardware handshaking. DSR is always active (connected to ground) while the modem is
on. RING may be used to alert the host to a variety of incoming calls.
For a minimal implementation, connect RxData and TxData to the COM port serial data lines, and connect
DTR and RTS to GND.
The electrical characteristics for the I/O lines are the same as the General Purposes Input/Output (GPIO)
lines.
RING
CTS
DTR
DSR
RTS
Rx
Tx
Enabler IIG
UART
DCD
Host
