ELM327P datasheet(21/76 Pages) ELM

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ELM327

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AT Command Descriptions (continued)

an 83.3 kbps baud rate, close the protocol, and then

send the new values:

>AT PC

>AT PB C0 06

>AT MA

Values passed in this way do not affect those that

are

stored

the

and

Programmable

Parameters, and are lost if the ELM327 is reset. If you

want to make your settings persist over power cycles,

then you should store them in the Programmable

Parameter memory (don’t forget that there are two –

USER1 and USER2.

[ 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 Parameters section (page 55) 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

had entered PP OFF for every possible one.

It is possible to alter some of the Programmable

Parameters so that it may be difficult, or even

impossible, to communicate with the ELM327. If this

occurs, there is a hardware means of resetting all of

the Programmable Parameters at once. Connect a

jumper from circuit common to pin 28, holding it there

while powering up the ELM327 circuit. Hold it in

position until you see the RS232 Receive LED begin to

flash (which indicates that all of the PPs have been

turned off). At this point, remove the jumper to allow

the IC to perform a normal startup. Note that a reset of

the PPs occurs quite quickly – if you are holding the

jumper on for more than a few seconds and do not see

the RS232 receive light flashing, remove the jumper

and try again, as there may be a problem with your

connection. This feature is only available beginning

with v1.2, and is not a provided with any earlier

versions of the ELM327 IC.

PP hh ON

[ turn Programmable Parameter hh ON ]

This command enables Programmable Parameter

number hh. Once enabled, any value assigned using

the PP hh SV command will be used where the factory

default value was before. (All of the programmable

parameter values are set to their default values at the

factory, so enabling a programmable parameter before

assigning a value to it will not cause problems.) The

actual time when the value for this parameter becomes

effective is determined by its type. Refer to the

Programmable Parameters section (page 55) for more

information on the types.

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

enables all of the Programmable Parameters at the

same time.

PP hh SV yy [ Prog. Param. hh: Set the Value to yy ]

A value is assigned to a Programmable Parameter

using this command. The system will not be able to

use this new value until the Programmable Parameter

has been enabled, with PP hh ON.

PPS

[ Programmable Parameter Summary ]

The complete range of current Programmable

Parameters are displayed with this command (even

those not yet implemented). Each is shown as a PP

number followed by a colon and the value that is

assigned to it. This is followed by a single digit – either

‘N’ or ‘F’ to show that it is ON (enabled), or OFF

(disabled),

respectively.

See

the

Programmable

Parameters section for a more complete discussion.

R0 and R1

[ Responses off or on ]

These commands control the ELM327’s automatic

receive (and display) of the messages returned by the

vehicle. If responses have been turned off, the IC will

not wait for a reply from the vehicle after sending a

request, and will return immediately to wait for the next

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