What’s The Difference Between DGN and PGN?
In the context of CAN bus communication, particularly in protocols like J1939 or RV-C (used in vehicles, RVs, and heavy equipment), PGN (Parameter Group Number) and DGN (Data Group Number) are related but serve distinct roles. Here’s the difference:
PGN (Parameter Group Number):
- Definition:
- A PGN is a standardized identifier used in the J1939 protocol to describe the structure and meaning of the data being transmitted on the CAN bus.
- It defines the message’s purpose, its data format, and how it should be interpreted.
- Structure:
- A PGN is a 24-bit number embedded within the CAN ID. It provides information about:
- Priority: The importance of the message (higher priority messages are sent first).
- Data Page: Indicates extended data messages.
- PDU Format and Specific: Describes the type of data and its addressing mode (global or specific).
- A PGN is a 24-bit number embedded within the CAN ID. It provides information about:
- Use Case:
- The PGN helps devices on the network understand what type of data is being transmitted (e.g., engine temperature, vehicle speed, etc.).
- Examples:
0xFEF1
: Engine Temperature.0x18F004
: Vehicle Speed.
- Context:
- PGNs are central to the J1939 protocol and are widely used in automotive, industrial, and marine applications.
DGN (Data Group Number):
- Definition:
- A DGN is a term more commonly used in RV-C (a derivative of J1939) to describe a grouping of related data parameters. It is similar in purpose to a PGN but used in the RV-C protocol.
- Structure:
- Like PGNs, DGNs are typically associated with identifiers in the CAN ID.
- DGNs in RV-C often use a format similar to J1939, but they focus on RV-specific functionality like battery monitoring, generator control, and HVAC systems.
- Use Case:
- DGNs help define the data specific to recreational vehicles (e.g., chassis battery voltage, generator status, etc.).
- Examples:
0x1FFFD
: Battery Voltage and Current.0x1FFF4
: Ignition and Mobility Status.
- Context:
- The DGN terminology is mostly confined to RV-C, a subset of J1939 designed for recreational vehicles.
Key Differences:
Aspect | PGN (Parameter Group Number) | DGN (Data Group Number) |
---|---|---|
Protocol | Used in J1939 (automotive, industrial) | Used in RV-C (recreational vehicles) |
Purpose | Defines data structure for J1939 | Defines data structure for RV-C |
Scope | Broader, includes many industries | Specific to RV systems and devices |
Examples | Engine RPM, Fuel Rate, etc. | Chassis Battery Voltage, HVAC status |
Summary:
- PGN is a term from J1939, while DGN is used in RV-C. Both represent identifiers for structured data but are tailored to their respective protocols.
- If you’re working with general CAN bus communication in vehicles or heavy machinery, you’ll encounter PGNs.
- If you’re working in RV-specific systems, you’ll deal with DGNs, which are essentially adapted from PGNs for RV applications.
Credit: ChatGPT
[…] use the term PGN’s or Program Group Numbers. For more info about the difference, see here. One thing that sets RV-C apart from other CAN protocols is its ability to do […]