ELM329LP datasheet(21/87 Pages) ELM

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ELM329L

ELM329L DSA

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AT Command Descriptions (continued)

an error if attempted under any other conditions. Note

also that this version of the ELM329 only displays

responses that match the criteria, not the requests that

are asking for the PGN information.

MP hhhh n

[ Monitor for PGN, get n messages ]

This is very similar to the previous command, but

adds the ability to set the number of messages that

should be fetched before the ELM329 automatically

stops monitoring and prints a prompt character. The

value ‘n’ may be any single hex digit.

MP hhhhhh

[ Monitor for PGN hhhhhh ]

This command is very similar to the MP hhhh

command, but it extends the number of bytes provided

by one, so that there is complete control over the PGN

definition (it does not make the assumption that the

Data Page bit is 0, as the MP hhhh command does).

This allows for future expansion, should additional

PGNs be defined with the Data Page bit set. Note that

internally, the filter and mask are set using the values

provided, but only the Data Page bit is relevant in the

mask - the other bits are ignored. If you need more

precise matching of the priority and EDP bits, you

might consider the AT CM and AT CF commands to

set the filter and mask, then use AT MA.

MP hhhhhh n

[ Monitor for PGN, get n messages ]

This is very similar to the previous command, but it

adds the ability to set the number of messages that

should be fetched before the ELM329 automatically

stops monitoring and prints a prompt character. The

value ‘n’ may be any single hex digit.

PB xx yy

[ set Protocol B parameters ]

This command allows you to change the protocol

B (USER1) options and baud rate without having to

change the associated Programmable Parameters.

This allows for quicker testing, and program control.

To use this feature, simply set xx to the value for

PP 2C (the formatting options), and yy to the value for

PP 2D (the baud rate divisor), and send this

command. The next time that the protocol is initialized

it will use these values.

For example, assume that you wish to try

monitoring a system that uses 11 bit CAN at

33.3 kbps. If you do not want any special formatting,

this means a value of 11000000 (C0 hex) for PP 2C,

while 33.3 is 500/15 so 15 decimal or 0F hex is

needed for PP 2D. Send these values to the ELM329

in one command:

>AT PB C0 0F

then monitor:

>AT MA

If you want to try another protocol (for example,

500 kbps J1939) then simply close the current protocol

and send another AT PB command:

>AT PC

>AT PB 42 01

>AT MA

Values passed in this way do not affect those that

are

stored

the

and

Programmable

Parameters, and are lost if the ELM329 is reset. If you

want to make your settings persist over power cycles,

then you must store them in the Programmable

Parameter memory for one of the five USER protocols

(ie protocols B to F).

[ Protocol Close ]

There may be occasions where it is desirable to

stop (deactivate) a protocol. Perhaps you are not using

the automatic protocol finding, and wish to manually

activate and deactivate protocols. Perhaps you wish to

stop the sending of idle (wakeup) messages, or have

another reason. The PC command is used in these

cases to force a protocol to close.

PP hh OFF

[ turn Prog Parameter hh OFF ]

This command disables Programmable Parameter

number hh. Any value assigned using the PP hh SV

command will no longer be used, and the factory

default setting will once again be in effect. The actual

time when the new value for this parameter becomes

effective is determined by its type. Refer to the

Programmable Parameter Summary section (page 66)

for more information on the types.

Note that ‘PP FF OFF’ is a special command that

disables all of the Programmable Parameters, as if you

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