ELM327
AT Commands
Several parameters within the ELM327 can be
ELM327 will reply with the characters ‘OK’, to say that
it was successfully completed.
adjusted in order to modify its behaviour. These do not
normally have to be changed before attempting to talk
to the vehicle, but occasionally the user may wish to
customize these settings – for example by turning the
character echo off, adjusting a timeout value, or
changing the header bytes. In order to do this, internal
‘AT’ commands must be used.
Those familiar with PC modems will immediately
recognize AT commands as a standard way in which
modems are internally configured. The ELM327 uses
essentially the same method, always watching the
data sent by the PC, looking for messages that begin
with the character ‘A’ followed by the character ‘T’. If
found, the next characters will be interpreted as an
internal configuration or ‘AT’ command, and will be
executed upon receipt of a terminating carriage return
character. If the command is just a setting change, the
Some of the following commands allow passing
numbers as arguments in order to set the internal
values. These will always be hexadecimal numbers
which must generally be provided in pairs. The
hexadecimal conversion chart in the OBD Commands
section (page 29) may be helpful if you wish to
interpret the values. Also, one should be aware that for
the on/off types of commands, the second character is
the number 1 or the number 0, the universal terms for
on and off.
The remainder of this page, and the two pages
following provide a summary of all of the commands
that the current version of the ELM327 recognizes. A
more complete description of each command begins
on page 11. Note that the settings which are shown
with an asterisk (*) are the default values.
AT Command Summary
General Commands
Programmable Parameter Commands
<CR>
BRD hh
BRT hh
D
repeat the last command
try Baud Rate Divisor hh
set Baud Rate Timeout
set all to Defaults
PP xx OFF disable Prog Parameter xx
PP FF OFF all Prog Parameters disabled
PP xx ON enable Prog Parameter xx
PP FF ON all Prog Parameters enabled
PP xx SV yy for PP xx, Set the Value to yy
E0, E1
FE
Echo off, or on*
Forget Events
PPS
print a PP Summary
I
print the version ID
L0, L1
LP
Linefeeds off, or on
go to Low Power mode
Memory off, or on
Voltage Reading Commands
CV dddd
CV 0000
RV
Calibrate the Voltage to dd.dd volts
M0, M1
RD
restore CV value to factory setting
Read the input Voltage
Read the stored Data
Save Data byte hh
SD hh
WS
Warm Start (quick software reset)
reset all
Other
IGN
Z
@1
display the device description
display the device identifier
read the IgnMon input level
@2
@3 cccccccccccc store the @2 identifier
ELM327DSI
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