Understanding your vehicle’s data is crucial for diagnostics and performance tuning. The Controller Area Network (CAN) bus system is the backbone of modern vehicle communication, and accessing this data often involves the On-Board Diagnostics II (OBD2) port. While the term “Hdmi To Obd2” might suggest a direct connection for video output, the reality is more nuanced and technically fascinating, especially when diving into the intricacies of CAN bus communication.
The original forum discussion highlights the challenges and methods involved in intercepting and interpreting CAN bus data. The users are grappling with understanding Protocol Identifier (PID) values and how to effectively “sniff” CAN bus traffic to extract meaningful information. This is a critical step for anyone looking to go beyond basic OBD2 diagnostics and truly understand what’s happening under the hood of their vehicle.
One user, “ecoboostsho,” shares valuable insights based on their experience with an OBDLink MX adapter and the STN1100 chipset. They outline a series of AT commands used to establish a connection and configure the adapter for CAN bus communication. These commands are essential for setting up the communication protocol, timeouts, and headers needed to interact with the vehicle’s modules.
ATI (Just prints ELM 327 version ID string)
STI (Prints Firmware ID string)
STP53 (Sets Protocol to 53 - MS CAN as an example)
ATPC (Protocol Close)
ATE0 (Echo off)
ATL0 (Line Feed Off)
ATH1 (Headers On)
ATST32 (Sets timeout to 32ms)
ATS0 (Print Spaces off)
ATAT1 (Adaptive timing Auto)
ATCAF1 (Automatic Formatting On)
ATTP6 (Try Protocol 6)
ATBI (Bypass Initialization sequence)
ATAL (Allow long messages)
ATSH0007E0 (Set header to 00 07 E0 - this is typically your scan tool address if I recall correctly)
STCAFCP7E0,726 (Adds a flow control 11-bit ID pair, 7E0 is your scan tool and 726 is your target module address...you could request a known PID from the AWD module and see what header it responds with and use that going forward)These commands are not just arbitrary strings; they are specific instructions for the OBD adapter to communicate correctly with the vehicle’s CAN bus. For example, STP53 sets the protocol to MS CAN, a variant of CAN bus used in some vehicles. ATSH0007E0 sets the header, which is crucial for addressing messages to the correct module within the vehicle network. Understanding these commands is a deeper dive into OBD2 than simply plugging in a generic reader.
The discussion also touches upon the difficulty of identifying specific PIDs without prior knowledge or specialized tools. The original poster, “ecoboostsho,” suggests using a scan tool like FORSCAN to “sniff” the traffic between the PC and the car. This technique involves monitoring the communication between a known working scan tool and the vehicle to observe the commands and responses. By analyzing this captured data, it becomes possible to decipher the numeric values associated with different PIDs.
This process of reverse engineering PIDs is complex but necessary when trying to access vehicle data beyond the standard OBD2 parameters. It’s about understanding the language of the CAN bus and how different modules communicate with each other. The forum users are essentially working at a lower level, trying to uncover the raw data streams within the vehicle’s network.
The linked STN1100 chipset guide (https://www.scantool.net/scantool/downloads/98/stn1100-frpm.pdf) is a valuable resource for anyone wanting to delve deeper into OBD2 communication. It provides comprehensive information on the chipset’s capabilities and the AT commands that control it. This level of documentation is crucial for developers and enthusiasts who want to build custom OBD2 applications or understand the underlying communication protocols.
While the forum discussion doesn’t directly mention “HDMI to OBD2,” the context is highly relevant. If you’re thinking about “HDMI to OBD2,” you’re likely interested in displaying vehicle data on a screen, perhaps an in-car entertainment system or an external monitor. To achieve this, you first need to access and interpret the raw data from the OBD2 port, which, as the forum discussion illustrates, involves understanding CAN bus communication and potentially reverse engineering PIDs.
In conclusion, while a simple “HDMI to OBD2” cable might not be the direct solution for advanced vehicle diagnostics or data display, understanding the principles discussed in this forum is essential. Decoding CAN bus data, using tools like scan tools and OBD adapters with chipsets like STN1100, and being familiar with AT commands are all crucial steps in accessing and utilizing your vehicle’s data effectively. Whether you aim to display this data via HDMI or for other purposes, mastering these fundamentals is key to unlocking the full potential of OBD2 and CAN bus communication.
