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Design Of Proprietary Parameter Group Numbers (PGNs)

Posted by Wilfried Voss on

For a brief introduction to PGNs, see our post SAE J1939 Message Format and Interpretations of PGNs.

As the name Proprietary Parameter Group Numbers implies, the SAE J1939 standard supports Parameter Groups in PDU1 and PDU2 Format that manufacturers can assign for their specific needs, which includes the design of the data field in the message. The only constraint is that, per SAE request, “excessive” utilization of the network (e.g., 2 percent or more) should be avoided. This requirement is, however, not based on any technical restrictions by the CAN/J1939 network.

The following table shows the Parameter Group Number Range where the Proprietary Parameter Group Numbers are highlighted:

Proprietary Parameter Groups and their numbers are designed using the exact same structure as Parameter Group and their numbers defined by the SAE.

Parameter Group NameProprietary A
Parameter Group Number61184 (00EF00hex)
DefinitionProprietary PG using the PDU1 Format for Peer-to-Peer communication.
Transmission RateManufacturer Specific
Data Length0 – 1785 bytes (multi-packet supported)
Extended Data Page (R)0
Data Page0
PDU Format239
PDU Specific8-bit Destination Address – Manufacturer Assigned
Default Priority6
Data DescriptionManufacturer Specific
Parameter Group NameProprietary A2
Parameter Group Number126720 (01EF00hex)
DefinitionProprietary PG using the PDU1 Format for Peer-to-Peer communication.
Transmission RateManufacturer Specific
Data Length0 – 1785 bytes (multi-packet supported)
Extended Data Page (R)0
Data Page1
PDU Format239
PDU Specific8-bit Destination Address – Manufacturer Assigned
Default Priority6
Data DescriptionManufacturer Specific
Parameter Group NameProprietary B
Parameter Group Number65280 - 65535 (00FF00hex – 00FFFFhex)
DefinitionProprietary PG using the PDU2 Format for Broadcast communication.
Transmission RateManufacturer Specific
Data Length0 – 1785 bytes (multi-packet supported)
Extended Data Page (R)0
Data Page0
PDU Format255
PDU SpecificGroup Extension – Manufacturer Assigned
Default Priority6
Data DescriptionManufacturer Specific

Note: For reasons unknown, the SAE J1939/21 standard does not define a Proprietary B2 Parameter Group Name, which would be the same as Proprietary B, but with Data Page = 1. Setting Data Page = 1 is used, for instance, to define Proprietary A2. In all consequence, there is no reason not to describe Proprietary B2.

The use of Proprietary Parameter Group Numbers does, however, come with a downside, which is briefly mentioned by SAE J1939/21 in the Proprietary B PGN definition. In fact, the problem does apply to all Proprietary Parameter Group Numbers.

The potential problem comes with the possibility that two or more manufacturers may use the same Proprietary Parameter Group Number. SAE J1939/21 recommends that receivers of such messages need to differentiate between manufacturers, which can be accomplished by checking the Manufacturer Code in the ECU’s NAME.

Design of Proprietary PGNs

  • Allow end-users to set up the PGN in the range from 00F00 to 00FFFF, which allows them to work around existing proprietary PGNs in the network. This requires that the end users analyze and filter the SAE J1939 data traffic and determine which (if any) proprietary PGN is already in use.
    Note: Using the ECU’s NAME, as recommended by SAE J1939/21, doesn’t make a lot of sense since the NAME is only used during the Address Claim procedure.
  • Define the message frequency and priority that fits your node’s functionality best but does not interfere with the current network setup. The point is, be careful with the use of high message frequencies and/or high priorities.
  • Mere diagnostic messages should only be transmitted as a response to a Message Request.
  • Do not use message lengths greater than eight bytes when your data is of high priority and/or requires a high message frequency. Message lengths of greater than eight bytes require the use of the Transport Protocol (TP), which, when invoked at high frequency and high priority, would negatively impact the network performance.
  • Messages with more than eight data bytes, invoking the Transport Protocol, should only be transmitted as a response to a Message Request.

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