Siemens SIMATIC PN/BACnet LINK, Руководство по эксплуатации

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Functions
4.3 Cyclic data exchange between controller and PN/BACnet LINK
PN/BACnet LINK
Operating Instructions, 10/2017, A5E39895543-AA
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Status information on BACnet objects
The status information of the BACnet objects on the PN/BACnet LINK is exchanged with the
S7 controller via the process image.
Server objects
With server objects, the PN/BACnet LINK writes the status information transferred by the S7
controller to the property "Status_Flags" of the corresponding objects.
Client object references
The status information from the property "Status_Flags" of the affected objects is transmitted
as input data to the S7 controller.
Note
The flags for client object references do not have a valid value until the corresponding object
has been accessed from the PN/BACnet LINK at least once. As long as such access has not
taken place, the corresponding "Out_Of_Service" status flag has the value "TRUE" (default).
Until the first access this has the meaning "Status not defined". The following applies after
the first access: The flags always reflect the status on the last access. The current status of
a value may vary from the the status on the last access.
Transmission of status information
With "Binary input" objects, this status information is transmitted in accordance with the table
below in the four most significant bits of the byte to be transmitted. With objects of the type
"Binary output", "Analog input" and "Analog output" the status information is transmitted in an
additional byte.
Bit Meaning
7 OUT_OF_SERVICE
6 OVERRIDDEN
5 FAULT
4 IN_ALARM
3 Not assigned
2 Not assigned
1 Not assigned
0 Present_Value