Four physical networks, two routers

Figure 12.   Ethernet, MS/TP and ARCnet

Routers A and B join together three media and link-layer types: BACnet over Ethernet (network 2), BACnet MS/TP (networks 11 and 22), and BACnet ARCnet (network 8). Each BACnet node has a unique Device ID number (shown inside the node circle). Router A could actually be a remote station that is licensed for MS/TP (next example).

BACnet Ethernet to MS/TP router functions provided by the station in a remote host

This internetwork includes an Ethernet/IP backbone.

Figure 13.   Ethernet and MS/TP

In this case, the host’s station provides BACnet routing between the two MS/TP networks and an Ethernet network. On an Ethernet LAN, there may be two separate BACnet networks sharing the same media: BACnet over Ethernet and BACnet/IP.

Same physical Ethernet LAN, router joins two BACnet networks

Each BACnet node has a unique Device ID number (shown inside the node). This router function could actually be provided by a host station.

Figure 14.   Two networks

BACnet/IP to BACnet/Ethernet router function provided by a station

The controller or BACnet Supervisor manages this network with both BACnet/IP and BACnet Ethernet enabled.

Figure 15.   Two networks

In this case, be especially careful that no other router exists between the BACnet Ethernet and BACnet/IP networks. If the host station detects this illegal (loop) configuration, it stops its routing functions. This condition is indicated on the Property Sheet of the Bacnet Comm > Network component, where its Routing Enabled property is automatically set back to false (from true). Corresponding entries are generated in the station's LogHistory, which records the detected mis-configuration and disabled BACnet router functionality.