ELM327
Section Index
Description and Features....................................................................................... 1
Pin Descriptions..................................................................................................... 2
Ordering Information.............................................................................................. 3
Absolute Maximum Ratings....................................................................................4
Electrical Characteristics........................................................................................ 4
Overview................................................................................................................ 5
Communicating with the ELM327...........................................................................5
AT Commands....................................................................................................... 6
AT Command Summary.......................................................................................17
Reading the Battery Voltage................................................................................ 18
OBD Commands.................................................................................................. 19
Talking to the Vehicle........................................................................................... 20
Interpreting Trouble Codes...................................................................................21
Resetting Trouble Codes......................................................................................22
Quick Guide for Reading Trouble Codes............................................................. 22
Bus Initiation.........................................................................................................23
Wakeup Messages...............................................................................................23
Selecting Protocols...............................................................................................24
OBD Message Formats........................................................................................25
Setting the Headers..............................................................................................27
Monitoring the Bus............................................................................................... 30
CAN Messages and Filtering................................................................................31
Multiline Responses............................................................................................. 32
CAN Message Formats........................................................................................ 34
Altering Flow Control Messages...........................................................................35
J1939 Support...................................................................................................... 36
Restoring Order....................................................................................................37
Programmable Parameters.................................................................................. 38
Using Higher RS232 Baud Rates.........................................................................42
Computer Control................................................................................................. 44
Error Messages.................................................................................................... 44
Example Applications........................................................................................... 46
ELM327DSC
Elm Electronics – Circuits for the Hobbyist
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