Rockwell RCV144ACx, Command Reference Manual, Page: 56 / 186

AT Command Reference Manual
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3.7 CELLULAR COMMANDS
The Direct Connect Modem allows a direct interface to most cellular telephones eliminating the need for other intelligent
interfaces.
Landline modems operate with the telephone system by either going off hook detecting dialtone and the dialing the
telephone number using pulses or DTMF digits, or detecting the RING signal and answering the call. Intelligent cellular
phone interfaces connect between the modems RJ-11 socket and the cellular phone's data interface. The interface provides
landline features to the modem (line current, dial tone, ringing, etc.), and translates the modem's signals (off hook, DTMF
digits, etc.) into signals that the cellular phone understands. Once connected the interface acts as a transparent link between
the modem and the cellular telephone.
The Direct Connect Modem interfaces directly to the cellular phone's data interface and provides direct control over the
cellular phones operation. For example if the user were to instruct the modem to dial using the ATDTnnnn command the
modem would relay the telephone number and the SEND command to the cellular phone over the data interface.
The modem connects to the cellular phone using a special cable which must be purchased separately. A different cable is
required for each cellular phone or make of cellular phones. Below is a block diagram of a typical Direct Connect Cellular
Modem (based on AK14-X270 Rev 4 reference schematic).
3.7.1 Cellular Phone Drivers
The data interface to cellular phones differs between manufacturers and models and requires a unique cellular phone driver
for each phone or group of phones. Therefore the particular phone driver needs to be downloaded from the PC into the
modem's RAM before the modem can be used directly with the cellular phone. If a driver is not loaded the modem will
operate as a normal landline modem.
3.7.2 Cellular Commands
^C2 - Download Cellular Phone Driver
The ^C2 command initiates the cellular phone driver download function. Upon receipt of the command, the modem issues
the "OK" message. The user then performs an ASCII download of the driver (in .S37 format) from the host to the modem,
typically using a communications software package (with transmit pacing turned off).
^C2 Download Cellular Phone command
Result Codes:
OK
[Download Process]
OK Cellular phone driver download completed successfully
ERROR Cellular phone driver download not completed successfully, e.g., checksum of record (in S37 file)
is not correct, driver size is larger than 2k bytes, or an invalid driver is downloaded, or modem is
connected.
^I - Identify Cellular Phone Driver
The modem reports the identification of the loaded cellular phone driver in response to the ^I command. The response is
dependent upon the driver.
Result Codes (Typical):
CELLULAR DRIVER: OKI 900/910
(c) Copyright 1994, Spectrum Cellular, Inc.
Version 0.07 Thu Jan 10:29:52 1994
OK
or
ERROR Cellular phone driver is not loaded