HMS AnyBus-X J1939, Руководство пользователя

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J1939 Interface 6-4
© 2002 HMS Industrial Networks
Document Id:
SCM-7801-026
Handling Request PGNs
Requests referencing a PGN in an output data point will cause a message trans-
mission of that message. The message will be assembled and transmitted immedi-
ately in response to the request, regardless of the timing of the automatic
transmission.
Requests received that reference a PGN not configured in an output data point will
cause a NAK response if the request was destination specific. Broadcast requests
for non-configured PGNs will be ignored.
Destination Addresses
The destination address used for message transmission is dependant on the associ-
ated output data point configuration or the request message, whichever caused the
transmission. The rules for destination addressing follow.
• If the message PGN is a PDU2 type, all PDU2 messages are broadcast by
definition.
• If the transmission is automatic and the Target Address set to 255, the
message will be broadcast.
• If the transmission is automatic and the Target Address is not 255, the
message will be destination specific to the Target Address.
• If the transmission is due to a request and the request was destination spe-
cific, the message will be destination specific to the source address of the
request.
• If the transmission is due to a request and the request was broadcast, the
message will be broadcast.