User guide

BB2-7040 User Guide – Rev. 1.2 Page 2
a slave to a larger system. In this instance, the BB2-7040 should be reprogrammed with the ZigBee module functioning
as a router. Contact the factory about obtaining a router version of the BB2-7040.
Using ZigBee as a wireless link between a BACnet device and the BACnet network, with two BB2-7040’s – one on each
end – is possible. However, only one of the BB2-7040’s can be a coordinator, meaning one must be reprogrammed as a
router. Exchange of a small set of simple data points can be supported in this manner. BACnet protocol specification
does define BACnet tunneling over ZigBee. This tunneling is not yet supported by BB2-7040.
1.3 Object Server Model for a Gateway
Control Solutions gateways are not simple protocol translators. It is not possible to do an effective job of simply
converting one protocol directly to another. Any attempt to do so would likely have negative effects on the networks on
both sides of the gateway. An effective solution requires an intelligent device that can properly and efficiently act as a
native device on each network. Control Solutions gateways function as two native devices, one on each network, with a
shared data base in between them. They function as clients and/or servers on each network.
The central data element in every Control Solutions gateway is an “object”. Each object has rules for accessing that
object which are specific to the protocol of the network. Each object has at least two sets of rules, one set for each of the
two (or more) networks that may access the object. The object model is often optimized to cater to a specific protocol,
and will most often favor the more complex protocol. For example, all Control Solutions gateways that include BACnet
connectivity will have objects that are defined primarily as BACnet objects, with auxiliary rules for accessing the objects
via Modbus (or some other protocol).
Control Solutions gateways function as servers, providing a copy of the most recent data found in its data base when a
client requests that data. In master/slave terms, the server is a slave while the client is a master. Some applications will
treat the gateway as a server from both (all) networks connected. But most applications will want the gateway to be a
server on one side, and a client on the other side.