User's Manual

GM29 INTEGRATOR’S MANUAL

LZT 123 7361 R1A

2.5.1 Serial Data

The modem supports the standard data character format of 1 start bit,

8 bit data, no parity plus 1 stop bit, in total 10 bits per character.

2.5.2 Serial Data Signals - RD, TD

The default baud rate is 9.6kbps, however higher bit rates up to 460kbps

are supported. At start-up the GM29 transmits and receives data at the

default rate of 9.6kbps in either standard AT mode or binary mode (the

first received data - AT or binary format - determines the operating

mode). When reprogramming, the transmission rate is automatically

negotiated by the programming application. Speeds up to 460kbps are

supported.

Serial Data From Modem (RD)

RD is an output signal that the modem uses to send data to the

application.

Serial Data To Modem (TD)

TD is an input signal, used by the application to send data to the modem.

2.5.3 Control Signals - RTS, CTS, DTR, DSR, DCD, RI

RTS and CTS are capable of transmitting at 1/10th of the data

transmission speed for data rates up to 460kbps (byte-oriented flow

control mechanism).

Request to Send (RTS)

Used to condition the DCE for data transmission. The default level is

high by internal pull up.

The exact behaviour of RTS is defined by an AT command. Software

or hardware control can be selected. Hardware flow is the default

control.

The application must pull RTS low to communicate with the modem.

The modem will respond by asserting CTS low, indicating it is ready for

communication.

Clear To Send (CTS)

CTS indicates that the DCE is ready to transmit data. The default level

is high. You can define the exact behaviour of CTS through an AT

command, and can select software or hardware flow control.