RF Innovations CRESCENDO VHF HALF-DUPLEX, User Manual, Page: 12 / 74

Configuration
Crescendo VHF Half-Duplex User Manual Page 12 of 74
3.4 Hayes AT Command Interface
The Crescendo radio supports Hayes ATtention commands. These are used to query radio configuration and
performance parameters, set radio configuration, and establish communication links between radios over the
air.
For a port to accept AT commands it must be first in local command mode. See section 6.5.3 on page 36 for
information on enabling and disabling local command mode.
The format for the query and configuration AT command is:
ATxxx<[I1, I2, … In]><=value><TERM>
Where:
AT
is the attention code. All AT commands must be prefixed with
AT
. This is case insensitive, so
At
,
aT
, or
at
can also be used.
xxx
is the actual command. The list of valid AT commands is given in 0 on page 62.
<[I1, I2, … In]>
is an optional section that allows the specification of an index. Indexes are
used to access one of an array of similar items. For example, the Crescendo radio has two serial
ports which can both have different configurations. The command
ATS52[0]=1004
set the point-
to-point destination on the main port, while the command
ATS52[1]=1004
will set the point-to-
point destination on the auxiliary port.
<=value>
is an optional section that is used to set the value of a configuration parameter. If this
section is omitted, then the value of the configuration parameter will be displayed.
<TERM>
is the terminator for the AT command. A terminator can consist of a carriage return
(ASCII value 13
D
) or a carriage return followed by a line feed (ASCII value 10
D
).
For each AT command that is issued a response is generated. The list of responses to AT commands is
shown in Table 1.
Response
Code
Response
Number
Description
OK
0 Returned whenever a command is entered that is executed correctly.
CONNECT
1 Returned whenever a connection is established with a remote unit.
RING
2 Returned whenever this unit is dialled by a remote unit.
NO
CARRIER
3 Returned whenever a connection fails to be established, or is dropped while it
is operating.
ERROR
4 Returned whenever a command is invalid or could not be executed.
BUSY
7 Returned whenever an attempt is made to dial a remote unit and that unit
already has a connection established, or an attempt is made to enable the menu
via
AT?
but the menu system is already enabled on the other serial port.
NO
ANSWER
8 Returned whenever an attempt is made to dial a remote unit, and that unit fails
to answer.
Table 1: AT command response codes