ELM327LP datasheet(13/94 Pages) ELM

13 / 94 page

<CR>

[ repeat the last command ]

Sending a single carriage return character causes

the ELM327 to repeat the last command that it

performed. This is typically used when you wish to

obtain updates to a value at the fastest possible rate -

for example, you may send 01 0C to obtain the engine

rpm, then send only a carriage return character each

time you wish to receive an update.

[ Allow Long messages ]

The standard OBDII protocols restrict the number

of data bytes in a message to seven, which the

ELM327 normally does as well (for both send and

receive). If AL is selected, the ELM327 will allow long

sends (eight data bytes) and long receives (unlimited

in number). The default is AL off (and NL selected).

AMC

[ display Activity Monitor Count ]

The Activity Monitor uses a counter to determine

just how active the ELM327's OBD inputs are. Every

time that activity is detected, this counter is reset,

while if there is no activity, the count goes up (every

0.655 seconds). This count then represents the time

since activity was last detected, and may be useful

when writing your own logic based on OBD activity.

The counter will not increment past FF (internal logic

stops it there), and stays at 00 while monitoring.

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AT Command Summary (continued)

CAN Specific Commands (continued)

D0, D1

display of the DLC off*, or on

FC SM h

Flow Control, Set the Mode to h

FC SH hhh

FC, Set the Header to hhh

FC SH hhhhhhhh Set the Header to hhhhhhhh

FC SD [1 - 5 bytes] FC, Set Data to [...]

PB xx yy

Protocol B options and baud rate

RTR

send an RTR message

V0, V1

use of Variable DLC off*, or on

J1939 CAN Specific Commands (protocols A to C)

DM1

monitor for DM1 messages

use J1939 Elm data format*

JHF0, JHF1 Header Formatting off, or on*

use J1939 SAE data format

JTM1

set Timer Multiplier to 1*

JTM5

set Timer Multiplier to 5

MP hhhh

Monitor for PGN 0hhhh

MP hhhh n “

“ and get n messages

MP hhhhhh Monitor for PGN hhhhhh

MP hhhhhh n

“

“ and get n messages

AT Command Descriptions

The following describes each AT Command that the

current version of the ELM327 supports:

AMT hh

[ set the Act Mon Timeout to hh ]

When the Activity Monitor Count (ie time) exceeds

a certain threshold, the ELM327 decides that there is

no OBD activity. It might then give an ACT ALERT

message or switch to Low Power operation, depending

on how the bits of PP 0F are set. The threshold setting

is determined by either PP 0F bit 4, or by the AT AMT

value, should you provide it. The actual time to alarm

will be (hh+1) x 0.65536 seconds. Note that a value of

00 is accepted for AMT, but is used to block all Activity

Monitor outputs.

[ Automatically set the Receive address ]

Responses from the vehicle will be acknowledged

and displayed by the ELM327, if the internally stored

receive

address

matches

the

address

that

the

message is being sent to. With the auto receive mode

in effect, the value used for the receive address will be

chosen based on the current header bytes, and will

automatically be updated whenever the header bytes

are changed.

The value that is used for the receive address is

determined based on such things as the contents of

the first header byte, and whether the message uses

physical addressing, functional addressing, or if the

user has set a value with the SR or RA commands.

Auto Receive is turned on by default, and is not

used by the J1939 protocol.

ELM327LP Datenblatt(PDF) 13 Page - ELM Electronics

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