Elm327 Use Manual - How to use elm327 obd 2 scanner

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How to use elm327,the elm327 use manual.he ELM327 is a programmed microcontroller produced by ELM Electronics for translating the on-board diagnostics (OBD) interface

Transcript of Elm327 Use Manual - How to use elm327 obd 2 scanner

  • 1. ELM327OBD to RS232 Interpreter .c om opDescriptionFeatures Almost all of the automobiles produced today Power Control with standby mode share required, by law, to provide an interface for the l RS232 baud rates to 500 kbpsconnection of diagnostic test equipment. The dataootransfer on these interfaces follow several standards, Automatically searches for protocolsbut none of them are directly usable by PCs or smart.vt Fully configurable with AT commandsdevices. The ELM327 is designed to act as a bridgebetween these On-Board Diagnostics (OBD) ports Low power CMOS design wand a standard RS232 interface. w In addition to being able to automatically detect wand interpret nine OBD protocols, the ELM327 also Connection Diagramprovides support for high speed communications, a PDIP and SOIClow power sleep mode, and the J1939 truck and bus (top view)standard. It is also completely customizable, shouldyou wish to alter it to more closely suit your needs.MCLR OBD Tx LED The following pages discuss all of the ELM327sVmeasureOBD Rx LED omfeatures in detail, how to use it and configure it, as J1850 VoltsRS232 Tx LEDwell as providing some background information on .c J1850 Bus+ RS232 Rx LEDthe protocols that are supported. There are alsoMemoryCAN Rx pschematic diagrams and tips to help you to interface Baud RateCAN Tx hoto microprocessors, construct a basic scan tool, andLFmodeISO Lto reduce power consumption. ols VSSISO K XT1VDDtoApplications XT2VSS .vVPW InRS232 Rx Diagnostic trouble code readers ISO In RS232 Tx w Automotive scan toolsPWM InPwrCtrl / Busyw Teaching aidsJ1850 Bus- IgnMon / RTSBlock Diagram w 4.00 MHzBaud Rate 6MemoryMCLRXT19 10XT251LFmode7Vmeasure 2A/D RS232Rx18 RS232Command Converter RS232TxInterface17and ProtocolInterpreter ISO 15765-4ISO 9141-2 SAE J1850 PwrCtrl / Busy 16 SAE J1939ISO 14230-4PWM & VPWPower IgnMon / RTS 15Control 23 24 21 22 1234 14 13 1125 26 2728 OBD interfacesstatus LEDsELM327DSH VTOOLSHOP1 of 76Tel:+86-0755-27823977Web:http://www.vtoolshop.com

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ELM327Contents.c om opElectrical Information Pin Descriptions........................................................................... 3 Unused Pins.................................................................................5 h Ordering Information.................................................................... 5ls Absolute Maximum Ratings......................................................... 5o Electrical Characteristics..............................................................6 .vUsing the ELM327to Overview...................................................................................... 7 Communicating with the ELM327................................................ 7 w AT Commands............................................................................. 9 w AT Command Summary...............................................................9w AT Command Descriptions........................................................ 11 Reading the Battery Voltage...................................................... 27 OBD Commands........................................................................ 28 Talking to the Vehicle.................................................................29 Interpreting Trouble Codes........................................................ 31 Resetting Trouble Codes........................................................... 32om Quick Guide for Reading Trouble Codes................................... 32 Bus Initiation...............................................................................33 .c Wakeup Messages.....................................................................33 op Selecting Protocols.................................................................... 34 OBD Message Formats..............................................................35sh Setting the Headers................................................................... 37ol Monitoring the Bus..................................................................... 40 CAN Messages and Filtering..................................................... 41 to Multiline Responses................................................................... 42 CAN Message Formats..............................................................44.v Restoring Order..........................................................................45w w Advanced Features Altering Flow Control Messages................................................ 46w Using CAN Extended Addresses............................................... 47 SAE J1939 Messages................................................................48 Using J1939............................................................................... 50 The FMS Standard.....................................................................53 Programmable Parameters........................................................ 54 Programmable Parameter Summary......................................... 55 Using Higher RS232 Baud Rates...............................................59 Setting Timeouts - AT ST and AT AT Commands..................... 61 Power Control............................................................................ 62Design ExamplesMicroprocessor Interfaces..........................................................64 Example Applications.................................................................65 Modifications for Low Power Standby Operation....................... 70Misc.Error Messages and Alerts.........................................................72 Outline Diagrams....................................................................... 74 Copyright and Disclaimer........................................................... 74 Index.......................................................................................... 75ELM327DSHVTOOLSHOP2 of 76 Tel:+86-0755-27823977 Web:http://www.vtoolshop.com 3. ELM327Pin Descriptions .c om op MCLR (pin 1)A momentary (>2sec) logic low applied to this input return and a linefeed character. If it is at a low level, shwill reset the ELM327. If unused, this pin should be lines will be terminated by a carriage return only.olconnected to a logic high (VDD) level. This behaviour can always be modified by issuing an AT L1 or AT L0 command.to Vmeasure (pin 2)vVSS (pin 8) .This analog input is used to measure a 0 to 5Vsignal that is applied to it. Care must be taken toCircuit common must be connected to this pin. wprevent the voltage from going outside of the supply wlevels of the ELM327, or damage may occur. If it is XT1 (pin 9) and XT2 (pin 10) wnot used, this pin should be tied to either VDD or VSS.A 4.000 MHz oscillator crystal is connected between these two pins. Loading capacitors as required by J1850 Volts (pin 3) the crystal (typically 27pF each) will also need to be This output can be used to control a voltage supply connected between each of these pins and circuit for the J1850 Bus+ output. The pin normally outputs common (Vss). a logic high level when a nominal 8V is required (for Note that this device has not been configured for om J1850 VPW), and a low level for 5V (for J1850 operation with an external oscillator it expects a PWM), but this can be changed with PP 12. If this.c crystal to be connected to these pins. Use of an switching capability is not required for your external clock source is not recommended. Also,op application, this output can be left open-circuited.note that this oscillator is turned off when in the Low Power or standby mode of operation. sh J1850 Bus+ (pin 4) ol This active high output is used to drive the VPW In (pin 11) J1850 Bus+ Line to an active level. Note that thisThis is the active high input for the J1850 VPW datato signal does not have to be used for the Bus- Line (as signal. When at rest (bus recessive) this pin should .v was the case for the ELM320), since a separatebe at a low logic level. This input has Schmitt trigger J1850 Bus- drive output is provided on pin 14.wave shaping, so no special amplification is w required. w Memory (pin 5) wThis input controls the default state of the memory ISO In (pin 12)option. If this pin is at a high level during power-up or This is the active low input for the ISO 9141 andreset, the memory function will be enabled by ISO 14230 data signal. It is derived from the K Line,default. If it is at a low level, then the default will beand should be at a high logic level when at rest (busto have it disabled. Memory can always be enabled recessive). No special amplification is required, asor disabled with the AT M1 and AT M0 commands.this input has Schmitt trigger wave shaping. Baud Rate (pin 6)PWM In (pin 13)This input controls the baud rate of the RS232 This is the active low input for the J1850 PWM datainterface. If it is at a high level during power-up or signal. It should normally be at a high level when atreset, the baud rate will be set to 38400 (or the rate rest (ie. bus recessive). This input has Schmittthat has been set by PP 0C). If at a low level, thetrigger wave shaping, so no special amplification isbaud rate will always be 9600. required. LFmode (pin 7) J1850 Bus- (pin 14)This input is used to select the default linefeed modeThis active high output is used to drive the J1850to be used after a power-up or system reset. If it is atBus- Line to an active (dominant) level for J1850a high level, then by default messages sent by thePWM applications. If unused, this output can be leftELM327 will be terminated with both a carriageopen-circuited.ELM327DSHVTOOLSHOP3 of 76 Tel:+86-0755-27823977 Web:http://www.vtoolshop.com 4. ELM327Pin Descriptions (continued).c omop IgnMon / RTS (pin 15) This input pin can serve one of two functions, discussion on page 70 (Modifications for Low Powersh depending on how the Power Control options Standby Operation) provides more detail on how to ol (PP 0E) are set. use this output. If both bit 7 and bit 2