ELM327 - Wikipedia, the free encyclopedia

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The ELM327 is a programmed microcontroller produced by ELM Electronics for translating the on-board diagnostics (OBD) interface found in most modern cars. The ELM327 command protocol is one of the most popular PC to OBD interface standards, and is also implemented by other vendors.

The original ELM327 is implemented on the PIC18F2480 microcontroller from Microchip Technology.

ELM327 is one of a family of OBD translators from ELM Electronics. Other variants implement only a subset of the OBD protocols.



The ELM327 abstracts the low-level protocol and presents a simple interface that can be called via a UART, typically by a hand-held diagnostic tool or a computer program connected by USB, RS-232 or Bluetooth. New applications include smartphones.

There are a large number of programs available that connect to the ELM327.[1]

The function of such software may include

Protocols supported by ELM327

  • SAE J1850 PWM (41.6 kbaud)
  • SAE J1850 VPW (10.4 kbaud)
  • ISO 9141-2 (5 baud init, 10.4 kbaud)
  • ISO 14230-4 KWP (5 baud init, 10.4 kbaud)
  • ISO 14230-4 KWP (fast init, 10.4 kbaud)
  • ISO 15765-4 CAN (11 bit ID, 500 kbaud)
  • ISO 15765-4 CAN (29 bit ID, 500 kbaud)
  • ISO 15765-4 CAN (11 bit ID, 250 kbaud)
  • ISO 15765-4 CAN (29 bit ID, 250 kbaud)

ELM327 command set

The ELM327 command set[2] is similar to the Hayes AT commands.

ELM327 alternatives

The STN1110[3] from OBD Solutions supports the ELM327 command set for compatibility with existing ELM327 software applications, and runs an extended command set in parallel that offers many enhanced features. [4] STN1110 is not pin-compatible with the ELM327 IC. The STN1110 was released in 2010 .[5]

Pirate clones

The 1.0 version of the ELM327 did not implement copy protection, and the PIC code was copied[6][7] and widely sold in devices claiming to contain an ELM327 device. Numerous problems have been reported[8] with Chinese clones, partially due to bugs inherent in the early code.

Although these pirate clones may contain the ELM327 v1.0 code, they may falsely report the version number as the current version provided by the genuine ELM327, and in some cases report an as-yet non-existent version.[9] The actual function of these pirate clones is nonetheless limited to the function of the original ELM327 v1.0, with inherent deficiencies.

See also


  1. ^ "ELM327 Compatible Software". IMechatronics. Retrieved 6 May 2012.
  2. ^ "ELM327 AT Commands". ELM Electronics. Retrieved 6 May 2012.
  3. ^ "STN1100". OBD Solutions. Retrieved 6 May 2012.
  4. ^ "STN1110 vs ELM327 Comparison". OBD Solutions. Retrieved 6 May 2012.
  5. ^ "STN1110 release announcement". Scantool. Retrieved 6 May 2012.
  6. ^ "83427-elm327-usb-vehicle-obd-2-scanner-tool". Priuschat forum. Retrieved 6 May 2012.[dubious ]
  7. ^ "ebay ELM327 mini guide". User review. eBay. Retrieved 6 May 2012.[dubious ]
  8. ^ "Why you shouldn’t buy an Elm327 Clone". Scantool. Retrieved 6 May 2012.
  9. ^ "ELM327 Product Information". ELM Electronics.

External links