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ELM327_13 参数 Datasheet PDF下载

ELM327_13图片预览
型号: ELM327_13
PDF下载: 下载PDF文件 查看货源
内容描述: OBD转RS232解释 [OBD to RS232 Interpreter]
分类和应用:
文件页数/大小: 82 页 / 393 K
品牌: ELM [ ELM ELECTRONICS ]
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ELM327  
AT Command Descriptions (continued)  
memory function is enabled (AT M1), and this new  
protocol that you are trying is found to be valid, that  
protocol will then be stored in memory as the new  
default.  
this command rather than AT Z, as AT WS will not  
affect the chosen RS232 baud rate.  
Z
[ reset all ]  
This command causes the chip to perform a  
TP Ah  
[ Try Protocol h with Auto ]  
complete reset as if power were cycled off and then on  
again. All settings are returned to their default values,  
and the chip will be put into the idle state, waiting for  
characters on the RS232 bus. Note that any baud rate  
that was set with the AT BRD command will be lost,  
and the ELM327 will return to the default baud rate  
setting.  
This command is very similar to the AT TP  
command above, except that if the protocol that is tried  
should fail to initialize, the ELM327 will then  
automatically sequence through the other protocols,  
attempting to connect to one of them.  
V0 and V1  
[ Variable data lengths off or on ]  
@1  
[ display the device description ]  
Many CAN protocols (ie ISO 15765-4) expect to  
send eight data bytes at all times. The V0 and V1  
commands may be used to override this behaviour (for  
any CAN protocol) should you wish.  
This command displays the device description  
string. The default text is ‘OBDII to RS232 Interpreter’.  
Choosing V1 will cause the current CAN protocol  
to send variable data length messages, just as bit 6 of  
PP 2C and PP 2E do for protocols B and C. It does not  
matter what the protocol should be doing - V1 will  
override that. This allows experimenting with variable  
data length messages on demand.  
If you select V0 (the default setting), the forced  
sending of variable length CAN messages is turned  
off. The format of the sent messages reverts to the  
protocol’s settings.  
@2  
[ display the device identifier ]  
A device identifier string that was recorded with  
the @3 command is displayed with the @2 command.  
All 12 characters and a terminating carriage return will  
be sent in response, if they have been defined. If no  
identifier has been set, the @2 command returns an  
error response (‘?’). The identifier may be useful for  
storing product codes, production dates, serial  
numbers, or other such codes.  
See the ‘Programming Serial Numbers’ section for  
more information.  
WM [1 to 6 bytes]  
[ set Wakeup Message to… ]  
This command allows the user to override the  
default settings for the wakeup messages (sometimes  
known as the ‘periodic idle’ messages). Simply provide  
the message that you wish to have sent (typically three  
header bytes and one to three data bytes), and the  
ELM327 will add the checksum and send them as  
required, at the rate determined by the AT SW setting.  
Default settings send the bytes 68 6A F1 01 00 for  
ISO 9141, and C1 33 F1 3E for KWP.  
@3 cccccccccccc  
[ store the device identifier ]  
This command is used to set the device identifier  
code. Exactly 12 characters must be sent, and once  
written to memory, they can not be changed (ie you  
may only use the @3 command one time). The  
characters sent must be printable (ascii character  
values 0x21 to 0x5F inclusive).  
If you are developing software to write device  
identifiers, you may be interested in the ELM328 IC, as  
it allows multiple writes using the @3 command (but it  
can not send OBD messages).  
WS  
[ Warm Start ]  
This command causes the ELM327 to perform a  
complete reset. It is very similar to the AT Z command,  
but does not include the power on LED test. Users  
may find this a convenient way to quickly ‘start over’  
without having the extra delay of the AT Z command.  
If using variable RS232 baud rates (ie AT BRD  
commands), it is preferred that you reset the IC using  
ELM327DSI  
Elm Electronics – Circuits for the Hobbyist  
www.elmelectronics.com  
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