RS232 R
ADIO
M
ODEM
2.3 Hayes or ‘AT’ Mode
232C-868FR1
The Hayes or 'AT' commands comply with the Hayes protocol used in PSTN modem standards. This
‘AT’ protocol or Hayes mode is used to program the modem parameters, based on the following
principle:
•
A data frame always begins with the 2 ASCII ’AT’ characters, standing for ‘ATtention’.
•
Commands are coded over one or several characters and may include additional data.
•
A command is always ended by a <CR> Carriage Return.
A
T
Command
Additional command
...
<CR>
Note: Register numbers and values used in the AT commands are in decimal format.
The only exception to this data-framing rule is the command to enter the enter AT-mode. In this case,
only the escape code (‘+++’ by default) must be typed and followed by a silent time at least equal to the
time out. <AT> and <CR> shall not be used.
Note: All characters of the same command must be typed in quickly to prevent a timeout before the
whole command has been entered. Alternatively commands can be cut and paste from notepad to
ensure the whole command is entered within the time limit.
Note: Generally a successful AT command will return 0 and an unsuccessful command will return E.
Despite its similarity to standard telecommunication modems, the 232C-868FR1 remains a radio link
modem and is consequently fitted with some particular additional “AT” commands.
2.4 Standard commands description
'+++'
Enter AT-mode.
This command gives an instant access to the modem parameter set-up (Hayes or AT-
mode), whatever the actual operating mode in process might be. This command shall not
be started with AT, but by a silent time duration whose parameter entering is defined in
milliseconds in Register S214. N.B.: By activating the AT-mode, the modem inactivates
radio reception.
Exit AT-mode
This command activates the operating mode as stored into register S220.
Display value of register n.
The modem operating parameters are stored in ‘S’ classified Registers. S Registers are
numbered from 0 to 512. Some parameters are standard for every Hayes type modems,
other are specific to the 232C-868FR1 modem (See section 2.6 for register descriptions).
Operating parameters are stored in EEPROM memory and automatically set-up during
modem reset and modem turn on.
Change value of register n to m.
Changed values of registers are automatically stored in the modem EEPROM memory.
Display values of Significant Registers.
All significant registers for the modem (radio configuration, serial configuration, operating
mode,) are sent to the serial link, ready to be displayed by software like Windows
HyperTerminal.
Display values of the Modem Software version.
‘ATO’
'ATSn?'
'ATSn=m’
'AT/S’
'AT/V’:
DS232-4 June ’04
©2004 Reg. No. 227 4001, ENGLAND
Page 9
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