ELM327L
Contents
The Basics
Description................................................................................... 1
Features.......................................................................................1
Applications..................................................................................1
Block Diagram..............................................................................1
Connection Diagram.................................................................... 1
Pin Descriptions........................................................................... 4
ELM327L Unused Pins................................................................ 6
ELM327L Absolute Maximum Ratings.........................................7
ELM327L Electrical Characteristics............................................. 7
Using the ELM327
Overview...................................................................................... 9
Communicating with the ELM327................................................ 9
AT Commands........................................................................... 11
AT Command Summary.............................................................11
AT Command Descriptions........................................................ 13
Reading the Battery Voltage...................................................... 30
OBD Commands........................................................................31
Talking to the Vehicle.................................................................32
Bus Initiation...............................................................................34
Interpreting Trouble Codes........................................................ 35
Resetting Trouble Codes........................................................... 36
Quick Guide for Reading Trouble Codes................................... 36
Selecting Protocols.................................................................... 37
OBD Message Formats..............................................................39
Setting the Headers................................................................... 40
Multiline Responses...................................................................43
CAN Message Types................................................................. 45
Multiple PID Requests................................................................46
Response Pending Messages................................................... 46
CAN Receive Filtering - the CRA command.............................. 47
Using the CAN Mask and Filter..................................................48
Monitoring the Bus..................................................................... 49
Restoring Order..........................................................................50
Advanced Features
Using Higher RS232 Baud Rates...............................................51
Setting Timeouts - the AT ST and AT AT Commands............... 53
SAE J1939 Messages................................................................54
Using J1939............................................................................... 56
The FMS Standard.....................................................................59
The NMEA 2000 Standard.........................................................60
Periodic (Wakeup) Messages.................................................... 60
Altering Flow Control Messages................................................ 61
Using CAN Extended Addresses............................................... 62
CAN Input Frequency Matching.................................................63
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ELM327L DSA
Elm Electronics – Circuits for the Hobbyist
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