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 (v1.4b)
ELM327 - OBD to RS232 Interpreter (v1.3a)
ELM329 - CAN Interpreter (v1.0)
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): $14.50 ELM320SM (8-pin SOIC): $16.50
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): $14.50 ELM322SM (8-pin SOIC): $16.50
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): $15.50 ELM323SM (14-pin SOIC): $17.50
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 provide two generic CAN protocols that can be customized by the user for use with audio data busses, special OBD implementations, etc. It would seem that the previous version (1.3a) offered all that anyone could need in an OBD interpreter, but we've managed to find several new features to put into the new ELM327 v1.4b chip. The data sheet explains all of these features in detail, but here's a quick listing of some of the changes:
In addition, there have been several improvements made 'under the hood', which will help with the overall reliabilty. Download either the 'QuickSheet' (a 7 page summary), or the full (76 page) Data Sheet for a more complete description of what it is now 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.
- Power Control provides a very low power standby mode
- More J1939 support
- A non-volatile memory location for storing user data
- An option to turn off the CAN silent monitoring for bench testing, or when connecting to a dedicated CAN port
- CAN extended addressing support for experimenting with special data formats
- The ISO/KWP bus initializations may now be performed without having to send a request
- A 4800 baud ISO option, to compliment the 10400 and 9600 rates
- An SS command for searching sequentially through the protocols
- A TA command to change the Tester Address without using a PP
- The ability to quickly restore the factory calibration for the voltage reading circuit
We are currently shipping version 1.4b of the ELM327.
ELM327P (28-pin PDIP): $32.50 ELM327SM (28-pin SOIC): $32.50
ELM327
data sheet
(373K)
ELM327
quick sheet
(32K)
ELM327
AT Commands
(45K)
Please note: There is no ELM327 v1.4a ! Some clone makers have introduced what they call a 'v1.4a',
but we have never made one, and do not plan to make one.
Version 1.3a of the ELM327 is still available for purchase, at a lower price. This IC was great value for the money before, and now offers incredible value. It has more features than most people can use, so you will not go wrong if you pass over the v1.4b and buy this one instead. The main difference between the v1.3a and v1.4b chips is that the v1.4b offers the ability to go to a low power 'sleep' type mode. This is great for applications where it is preferred to keep the ELM327 connected to the vehicle (fleet applications, etc.). If you only want to occasionally connect to a vehicle to read trouble codes and maybe a little data, then seriously consider this v1.3a version.
ELM327P v1.3a (PDIP): $19.00 ELM327SM v1.3a (SOIC): $19.00
Please note that the above price is for any quantity - we do not offer any discounts on the ELM327 v1.3a with quantity.
ELM327 v1.3a
data sheet
(261K)
The ELM329 is our newest addition to the OBDII family. It takes the CAN features from the ELM327, and adds several other features our users have requested. To name a few: In addition, we've managed to get the interface working a little faster, maintained software compatibility with the ELM327, and maintained pin compatibility with the ELM327 too. Download a data sheet to find out more.
- CAN periodic (wakeup) messages
- Three more user controllable protocols (including 500 kbps J1939)
- Single wire CAN transceiver controls
- Some general purpose inputs and an output
- The ability to send an arbitrary CAN message at any time
- An expanded and more friendly CRA function
- An active LED
ELM329P v1.0 (PDIP): $21.00 ELM329SM v1.0 (SOIC): $21.00
ELM329 v1.0
data sheet
(335K)
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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