gefran BDI50 Series User Manual

App 3-20
3. BACnet Protocol Structure
BACnet is the communication protocol by way of protocol stack so the pocket is
composed of stacked layer types. Refer to the following figure.
When application program sends the BACnet service request for the pocket, it requires
requesting for executing BACnet request program in the application layer via application
program interface. The requirements of the program are sent to the application layer and
application protocol data unit (APDU) consists of Application Protocol Control Information
(APCI) and Servie Data of application program. Then APDU passes its messages downward
to BACnet request program in the network layer. APDU becomes Network Layer Protocol
Data Unit (NPDU) composed of Network Service Data Unit (NSDU) and Network Protocol
Control Information (NPCI). And so forth for the data link layer and physical layer to
complete the full service for the packet.
BACnet Service Request
Application Program
Application Layer
Network Layer
Data Link Layer
Physical Layer
A-BACnet.Request
N-UNITDATA.Request
DL-UNITDATA.Request
MA-UNITDATA.Request
P-UNITDATA.Request
APCI Service Data APDU
NSDUNPCI NPDU
LSDU LPDULPCI
MSDUMPCI
PSDUPPCI
MPDU
PPDU

gefran BDI50 Series Specifications

General

Brand	gefran
Model	BDI50 Series
Category	Inverter
Language	English