Packet (N_PDU)

In ISO Standards, the term Network Protocol Data Unit (N_PDU) is used. In this implementation, we refer to it as a Packet.

Packets are created during the segmentation of a diagnostic message. Each diagnostic message consists of at least one Packet (N_PDU).

A Packet contains the following fields:

Network Address Information

The Network Address Information (N_AI) field carries all addressing information.

It identifies:

  • The sender of the Packet

  • The recipient(s) of the Packet

  • The addressing type used

Network Data Field

The Network Data Field (N_Data) carries the diagnostic message content.

  • If the diagnostic message fits into a single Packet, N_Data contains the entire message.

  • If segmentation is used, N_Data carries only a portion of the message.

On some communication buses, certain Packets may not carry any data (e.g., CAN Flow Control), as they are used solely to manage the flow of packets.

Network Protocol Control Information

The Network Protocol Control Information (N_PCI) field identifies the type of the Packet (N_PDU). N_PCI values and their interpretation are specific to each communication bus.