Carel GATEWAYBN0, Руководство пользователя

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BACnet Gateway
Carel Cod. +030221110 rel. 2.4 del 17/12/02
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6.2.2 Implemented commands
For the description of BACnet capabilities supported by the Gateway refer to Appendix - PICS at the end of this manual .
The commands of the BACnet protocol implemented are ReadProperty, WriteProperty, Who-is and I-Am.
With this functions it is possible to read and write a single value at a time.
The object types supported are: Analog Value,
Binary Value and Device.
6.2.3 Maximum database
The maximum number of variables which can be transferred from a Carel peripheral to the Gateway is the following:
Variable type Max. number
digital
199
analog
127
integer 127
Table 6.2.2.1
The BACnet protocol does not distinguish between analog and integer variables; the Carel integer variables are tailored to
the analog variables and are then transferred to the BACnet database with a 128 (dec.) offset added to their addresses.
The maximum number of the transferable variables from the Gateway to the BACnet is:
Variable type Max. number Corresponding BACnet object
digital 199 binary value
analog
254
analog value
Table 6.2.2.2
WARNING : the complete and digital analogic variables with address 0 are not managed by the Carel peripherals.
Note that because of the variety of Carel machines, there is no distinction between the input variables (only reading) and the
output variables (reading/writing) so that the database knowledge and its management is entrusted to the side on the
supervisor.
Carel or the manufacturer of the connected units will be able to supply the meaning tables of the single variables contained in
the controllers.
6.2.4 Construction of a BACnet database starting from a Carel database
In a supervisor that uses the BACnet protocol, the database management related to a Carel peripheral must be done
remembering that the address of each variable must be thought as a sequence of addresses:
•
address with which the BACnet protocol sees the subnetwork of Carel peripherals, (see BACnet address of the Gateway in
Configuration );
•
address of the Carel controller within the Carel peripheral subnetwork;
•
address of the variable within the Carel peripheral (Instance of the corresponding object Analog Value or Binary Value).
The construction of a BACnet database implementable in a BACnet supervisor handling Carel peripherals can be done in the
following way:
•
the Carel digital variables are transferred with their addresses to the BACnet database
•
the Carel analog variables are transferred with their addresses to the BACnet database (added to the offset of the instance
of the Device object “Device obj Id offset” described in Configuration);
•
the Carel integer variables are tailored to the analog variables and are then transferred to the BACnet database with a
128 offset added to their addresses.