User's Manual

HAYES AT COMPATIBLE COMMAND SET

©©

234839, Revision 2.2

The Hayes

Compatible AT Command Set

he RFI-9256 supports many Hayes compatible commands and command sequences, this enables

users and operators to fully control and operate the Radio Modem and in most cases emulate land line

or phone modems for their communication needs. Some commands are implemented for completeness

only and do not perform any function.

The Hayes commands may be entered manually through a terminal or automated through dialer

programs and scripts. Most commands, with exception of the ‘%’ register (Table 7-5) and Connection

Commands (Table 7-3), may be concatenated into a single command string. Commands or command strings

must be terminated with a Carriage Return <CR> code produced by the Enter key. AT Commands may

be used if the terminal attached to the modem will not understand the menu system, for example a PLC

terminal. In addition to the modem configuration, AT Commands are used to dial and hang-up the remote

modem for Point to Multipoint Communication.

The AT Commands

The AT commands are a group of special commands recognised by your modem. These commands

derive their name from the letters AT, which are used to prefix commands. Before continuing:

Run your communications software and enter local mode (or terminal mode) at 19200-

baud, 8 bit data, No parity, One stop bit and no flow control or handshaking. If these values have

been changed for the modem then the communications software needs to be set the same as the

unit it is communicating to.

The Attention Code

An AT (sometimes known as the ATtention code) usually precedes all commands being sent to the

modem. It is used to gain the modem’s attention, informing it that you are about to send a command. For

example:

Type the command: ATI2 <CR>

Your modem’s firmware identity message will appear on your terminal screen. If you type I2 only, your

modem will not respond.

You may enter the attention code in all upper case, or all lower case letters, such as: AT or at

Multiple Commands

You may place multiple modem commands after an AT provided the total number of characters does

not exceed 255. For example, a valid command to display the modem’s internal temperature twice is: