ELM327_10 Datasheet, PDF (21/76 Pages) ELM Electronics – OBD to RS232 Interpreter

ELM327
AT Command Descriptions (continued)
an 83.3 kbps baud rate, close the protocol, and then
send the new values:
>AT PC
OK
>AT PB C0 06
OK
>AT MA
Values passed in this way do not affect those that
are stored in the 2C and 2D 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.
PC
[ 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
ELM327DSH
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