ELM329
AT Command Descriptions (continued)
stops monitoring and prints a prompt character. The
value ‘n’ may be any single hex digit.
cases to force a protocol to close.
PP hh OFF [ turn Prog Parameter hh OFF ]
PB xx yy
[ set Protocol B parameters ]
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 61)
for more information on the types.
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, and yy to the value for PP 2D, and issue the
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 or C0 for PP 2C, and
15 decimal or 0F hex for PP 2D. Send these values to
the ELM329 in one command:
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 become difficult, or even
impossible, to communicate with the ELM329. 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 ELM329 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.
>AT PB C0 0F
then monitor:
>AT MA
if you see CAN ERRORs, and realize that you wanted
an 83.3 kbps baud rate, close the protocol, and then
send the new values:
>AT PC
OK
>AT PB C0 06
OK
PP hh ON
[ turn Prog Parameter hh ON ]
>AT MA
This command enables Programmable Parameter
number hh. Once enabled, any value assigned using
the PP hh SV command will be used instead of the
factory default value. (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 60) for more
information on the types.
Values passed in this way do not affect those that
are stored in the 2C and 2D 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).
PC
[ Protocol Close ]
There may be occasions where it is desirable to
Note that ‘PP FF ON’ is a special command that
enables all of the Programmable Parameters at the
same time.
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
ELM329DSB
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