ELM323
AT Commands Summary
hexadecimal value from 00 to FF. The maximum
possible time delay of 5.10 seconds thus occurs when
a value of FF (or decimal 255) is used. The default
setting is 7D (or decimal 125) which provides a
nominal delay of 2.5 seconds between messages.
Note that the value 00 (zero) is treated as a very
special case, and must be used with caution. It is used
to stop all periodic messages, by telling the ELM323
internally that the bus is no longer active. This can be
convenient if the vehicle has timed out (perhaps when
using the AT MA command) and you wish to inform
the ELM323 of that without performing a full reset.
Issuing AT SW 00 will not change the previous setting
for the time between wakeup messages.
ELM323 AT Commands
general
D set all to Defaults
I show the ID string
Z reset all
Attempting to communicate with the vehicle after
issuing AT SW 00 will result in the ELM323 perfoming
a bus initialization sequence.
<CR> repeat last command
bus control
FI Fast Init
Z
[ reset all ]
SI Slow Init
This command causes the chip to perform a
complete reset as if power were cycled off and then on
again. All settings are returned to their default values,
and the chip will be put in the idle state, waiting for
characters on the RS232 bus.
SW hh Set Wake (hh*20ms)
responses
E1/0 Echo on/off
H1/0 Headers on/off
L1/0 Linefeeds on/off
FD use Formatted Data
PD use Packed Data
ST hh Set Timeout (hh*4ms)
Figure 1 shows all of the current ELM323 AT
commands in one convenient chart. In order to help
with the understanding of these, we have grouped the
commands into four functional areas, but this has no
bearing on how they need to be used – it is only for
clarity. You may find this chart to be useful when
experimenting with the IC.
requests
BD Buffer Dump
MA Monitor All
SH xx yy zz Set Header
AR Auto Receive
SR hh Set Rx address
Figure 1. ELM323 Command Summary
ELM323DSC
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