ELM325
AT Commands
Several parameters within the ELM325 can be
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, or adjusting a timeout value. 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 ELM325 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
ELM325 will reply with the characters ‘OK’, to say that
Some of the commands require that numbers be
provided as arguments, in order to set the internal
values. These will always be hexadecimal digits. 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 following is a summary of all of the current
ELM325 commands. A more complete description of
each command follows, starting on the next page.
AT Command Summary
General
J1708 Specific
<CR>
D
repeat the last command
set all to Defaults
AF0, AF1
C0, C1
F1
Auto Formatting off, or on*
Checksum display off*, or on
reset Filter 1
E0, E1
I
Echo off, or on*
print the version ID
Linefeeds off, or on*
Warm Start (quick software reset)
reset all
F2
reset Filter 2
L0, L1
WS
Z
F1 hh hh hh hh hh set Filter 1
F2 hh hh hh hh hh set Filter 2
GM
Get Message
GO
Get One message
MA
Monitor All messages
Monitor for MID hh messages
Monitor for PID hh messages
Monitor for page 2 PID hh
Set MID to hh
Other
MM hh
MP hh
MP 01hh
SM hh
SP h
TC
EM0, EM1
R0, R1
Error Messages off, or on*
Responses off, or on*
RE output pin low*, or high
Spaces off, or on*
RE0, RE1
S0, S1
Set Priority to h
ST hh
Set Timeout to hh
get Trouble Code messages
Note: Settings shown with an asterisk (*)
are the default values
ELM325DSA
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