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):

  1. 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.
  2. 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).
  3. Use Case:
    • The PGN helps devices on the network understand what type of data is being transmitted (e.g., engine temperature, vehicle speed, etc.).
  4. Examples:
    • 0xFEF1: Engine Temperature.
    • 0x18F004: Vehicle Speed.
  5. Context:
    • PGNs are central to the J1939 protocol and are widely used in automotive, industrial, and marine applications.

DGN (Data Group Number):

  1. 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.
  2. 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.
  3. Use Case:
    • DGNs help define the data specific to recreational vehicles (e.g., chassis battery voltage, generator status, etc.).
  4. Examples:
    • 0x1FFFD: Battery Voltage and Current.
    • 0x1FFF4: Ignition and Mobility Status.
  5. 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

One Comment to What’s The Difference Between DGN and PGN?

  1. […] 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 […]

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