Our "OBD Interpreter" ICs are designed for use with vehicles that use one of the standard OBDII
(On Board Diagnostics) protocols. Refer to the help > obd section to
see if your car uses one of these protocols.
OBD InterpretersELM320 - OBD (PWM) to RS232 Interpreter
ELM322 - OBD (VPW) to RS232 Interpreter
ELM323 - OBD (ISO) to RS232 Interpreter
ELM327 - OBD to RS232 Interpreter
OBD Software DevelopmentELM328 - OBD Device Identifier Test IC
The ELM320 allows you to talk to your 41.6KHz J1850 PWM protocol vehicle through a standard RS232 serial connection, using only simple ASCII commands. This data protocol was commonly used in many Ford Motor Company vehicles (but is now being replaced by CAN). The data sheet shows how to connect this IC into a low cost circuit which provides all the functionality of a scan tool that cost considerably more. Once built, a simple terminal application, and perhaps a USB to RS232 converter are all that are needed to 'talk' to your vehicle. You need only send a few simple keyboard commands (ascii characters) and all the data formatting, error checking, bus arbitration, etc. is then handled by the ELM320 for you.
If you presently use one of our v1.x ICs, you will be pleased to know that this version (v2.0) is pin-compatible with your IC (the only difference is that linefeeds are now on by default). If your IC is mounted in a socket, you can simply unplug the old IC and plug in the new.
ELM320P (8-pin PDIP): $16.50 ELM320SM (8-pin SOIC): $18.50
ELM320
data sheet
(74K)
Similar to the ELM320, the ELM322 is for connecting to an OBDII equipped vehicle which uses the 10.4KHz J1850 VPW format. This standard is typically used in General Motors Corporation and some (Daimler) Chrysler vehicles. As with all of our OBD ICs, the user need only issue the desired commands through an RS232 serial connection and the data formatting, error checking, bus arbitration, etc. on the vehicle side is taken care of by the ELM322. This allows experimenters to inexpensively create their own scan tool.
If you presently use one of our v1.x ICs, you will be pleased to know that this version (v2.0) is pin-compatible with the old, so you can simply replace your IC if you want to upgrade.
ELM322P (8-pin PDIP): $16.50 ELM322SM (8-pin SOIC): $18.50
ELM322
data sheet
(86K)
The ELM323 completes our trio of single function OBDII ICs. It supports the ISO 9141-2 and ISO 14230-4 standards that are used by many vehicles throughout the world. The ELM323 transparently converts between a 10.4KHz ISO data stream and standard ASCII characters, allowing trouble codes and operating parameters to be easily retrieved without the need for special software. No knowledge of data formatting, error checking, bus initiation etc. is needed either, as the ELM323 handles all of it for you.
The present version of the ELM323 (v2.0) provides several programmable features that the previous versions did not offer. It allows programmable header bytes, adjustable timeouts, the ability to report in the packed data mode, and offers a special monitoring mode as well. This is in addition to all of the capabilities that the v1.x ICs offered - the full seven byte command structure, two line (K and L) initiation, software selectable linefeeds and character echoing, and the visual feedback provided by the four LED outputs.
If you currently use one of our v1.x ICs, you will be pleased to know that this version (v2.0) is pin-compatible with the old, so you can simply replace your present IC with one of these, and immediately begin enjoying these new features.
ELM323P (14-pin PDIP): $17.50 ELM323SM (14-pin SOIC): $19.50
ELM323
data sheet
(92K)
The ELM327 is our multi-function OBDII Interpreter IC. It provides an RS232 to OBDII data bridge for systems that use the ISO 15765-4 CAN, SAE J1850 PWM, SAE J1850 VPW, ISO 9141-2, ISO 14230-4 and SAE J1939 protocols. In addition, we now provide two generic CAN protocols that can be customized by the user for use with audio data busses, special OBD implementations, etc. The new ELM327 v1.3 IC has taken the proven v1.2, added more error monitoring and recovery, added several more AT commands, has improved the CAN printing, and has added a few features that many of you have been asking for. To name just a few of the new features, you can now:
This IC is well proven, and continues to be a very popular choice for OBDII projects. Download either the 'QuickSheet' (a 6 page summary), or the full (59 page) Data Sheet for a more complete description of what it is capable of. We are often asked about the differences between versions of the ELM327, as it has been updated several times. The AT Commands file provides a summary of these.
- set the maximum number of responses to obtain
- remove spaces from ECU responses (to speed data transmission)
- permanently store a unique identifier in EEPROM
- set the CAN mask and filter with one command
- easily switch between variable and fixed CAN message lengths
- send CAN remote frames (RTRs)
We are currently shipping version 1.3a of the ELM327.
ELM327P (28-pin PDIP): $32.50 ELM327SM (28-pin SOIC): $32.50
ELM327
data sheet
(261K)
ELM327
quick sheet
(29K)
ELM327
AT Commands
(41K)
The ELM328 IC is electrically identical to the ELM327 except that it offers one new AT command which can be used to reset the @2 Device Identifier lock. This provides code developers with a means to repeatedly test code which writes to the @2 device identifier, without requiring a new IC each time. The ELM328 supports all of the ELM327 AT Commands, but does not transmit OBD messages - it is for code development only, and not for use in scan tools.
ELM328P (28-pin PDIP): $32.50 ELM328SM (28-pin SOIC): $32.50
ELM328
data sheet
(14K)
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