Siemens SITRANS FEC920, Руководство пользователя

Страница: 188 / 247

FEC920: USER GUIDE
Page 180 September 18
8 BACnet
8.1 BACnet Objects
In BACnet, objects are collections of properties, each representing some bit of information. In addition to
standard defined properties, objects may include vendor-defined properties as long as they function in
accordance with the standard. BACnet also defines the expected behavior from each property for that object.
What makes the object-oriented approach work is that every object and every property as defined by the system
is accessible in exactly the same manner.
8.2 BACnet Services
The process of reading or writing to a property is what BACnet calls a service. Services are the methods used
by any BACnet device when it communicates with another BACnet device, including retrieving information,
transmitting information or communicating an action. The standard defines a wide range of services for
accessing objects and their properties. See Section 8.3.5 for further details.
8.3 BACnet Object Mapping
8.3.1 Mapping to I/O and Loop Data Points
BACnet objects are mapped to FEC920 I/O and Loop data points as shown in Table 2.
Object types are denoted in the table as follows:
AI – Analog Input
AV – Analog Value
BI – Binary Input
BV – Binary Value
CS – Character String
MSI – Multi State Input
Input channels 5-8 are instantiated as BACnet objects if the 'Dual Input Channels' option is set to ‘05..08’.
Table 2: BACnet Object Representation of I/O and Loops
Object Name Type Data Parameter Equivalent Modbus Path R/W
Input Channel 1
Channel.1.Main.PV AI
PV Channel.1.Main.PV
R
PV Status Channel.1.Main.Status
Channel.1.Alarm1.Threshold AV AL1 Threshold Channel.1.Alarm1.Threshold R/W
Channel.1.Alarm1.Status MSI AL1 Status Channel.1.Alarm1.Status R
Channel.1.Alarm2.Threshold AV AL2 Threshold Channel.1.Alarm2.Threshold R/W
Channel.1.Alarm2.Status MSI AL2 Status Channel.1.Alarm2.Status R
Input Channel 2
Channel.2.Main.PV AI
PV Channel.2.Main.PV
R
PV Status Channel.2.Main.Status
Channel.2.Alarm1.Threshold AV AL1 Threshold Channel.2.Alarm1.Threshold R/W
Channel.2.Alarm1.Status MSI AL1 Status Channel.2.Alarm1.Status R
Channel.2.Alarm2.Threshold AV AL2 Threshold Channel.2.Alarm2.Threshold R/W
Channel.2.Alarm2.Status MSI AL2 Status Channel.2.Alarm2.Status R
A5E45696052A Rev-AA