NPCI

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The Network Protocol Control Information is the first part of a Network Protocol Data Unit.

The structure of the NPCI is variable and controlled by the NPCI Control Octet

The longest NPCI is 22 bytes, but hardly ever reaches this limit. To eke out the best use of a packet, the APDU size available should not be hardcoded, but calculated on the fly.


NPDU
NPDU
NPCI Octets Meaning Notes
1 Version (Always 0x01)
1 NPCI Control Octet Establishes if NSDU is a Network Layer Message or APDU
2 DNET Only present if DNET, DADR, Hopcount present flag set in NPCI Control Octet
1 DLEN Only present if DNET, DADR, Hopcount present flag set in NPCI Control Octet
Variable DADR Only present if DNET, DADR, Hopcount present flag set in NPCI Control Octet, (7 bytes max (LonWords Neuron ID))
2 SNET Only present if SNET, SADR present flag set in NPCI Control Octet
1 SLEN Only present if SNET, SADR present flag set in NPCI Control Octet
Variable SADR Only present if SNET, SADR present flag set in NPCI Control Octet. Is the 4 byte IP address and port number in BACnet/IP. (6 bytes max)
1 Hop Count Only present if DNET, DADR, Hopcount present flag set in NPCI Control Octet
NSDU Variable, either an APDU or a Network Message


See the specification clause 6.2 Network Layer PDU Structure



Keyword List
APDU BBMD BVLC BVLL DADR DNET Encoding I-Am LSAP MAC NPCI NPDU NSAP NSDU SA SADR SNET

Device Profiles

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Glossary



Keyword List
APDU BBMD BVLC BVLL DADR DNET Encoding I-Am LSAP MAC NPCI NPDU NSAP NSDU SA SADR SNET

Device Profiles

Edit this box.

Glossary