ELM323(2003) View Datasheet(PDF) - Elm Electronics

Part Name

Description

MFG CO.

ELM323
(Rev.:2003)

OBD (ISO) to RS232 Interpreter

Elm Electronics 

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internally that the bus is no longer active.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.

Attempting to communicate with the vehicle after

issuing AT SW 00 will result in the ELM323 perfoming

a bus initialization sequence.

Z

[ reset all ]

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.

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.

ELM323

ELM323 AT Commands

general

D set all to Defaults

I show the ID string

Z reset all

<CR> repeat last command

bus control

FI Fast Init

SI Slow Init

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)

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

Elm Electronics – Circuits for the Hobbyist

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