The ELM329 is our CAN-only device that provides more CAN support than is in our popular ELM327. The current firmware adds several new features that users have requested.
Features

• Supports ISO 15765, and SAE J1939
• Also provides five user controllable protocols
• Supports CAN periodic (wakeup) messages
• Has a CAN Monitor for automatically switching to low power mode
• Provides single wire CAN transceiver controls
• Has general purpose inputs and an output
• Can send an arbitrary CAN message at any time
• Has an expanded and more friendly CRA function
• Provides an active LED

In addition, we’ve improved code speed significantly over the v1.0 chip, increased the size of the RS232 transmit buffer, and maintained very good software and pin compatibility with the ELM327.
Documents

• Data sheet