The BACnet system used for this hotel is MS/TP on
EIA-485 twisted pair wire.
Communication varies from RS422/423 and
EIA-485 serial-communication to interconnectivity solutions including gateways and integrated DeviceNet, Ethernet and Palm for supporting applications from a remote location.
A rear serial communications port is available as either an EIA-232 or an
EIA-485 interface.
It comes equipped with one switch-selectable serial port and can communicate via EIA-232, EIA-422 or
EIA-485. The unit has a QVGA, 320 X 240 pixel, 256-color STN LCD display and is viewable in most lighting conditions.
The hard-wired system works through dedicated
EIA-485 (formerly called RS485) cabling or through an Ethernet connection that uses an existing network.
For the data acquisition in the measurement system are used the Advantech ADAM 4015 modules, which are able to communicate with the master system using the ModBus/ASCII protocol over the
EIA-485 industrial bus.
Communication varies from RS-422/423 and
EIA-485 serial-communication to interconnectivity solutions including gateways and integrated DeviceNet, Ethernet and Palm for supporting applications from a remote location.
The rational from the addendum sums things up: Although
EIA-485 practice allows for a third wire to connect transceiver common or reference points together so the receiver common mode rejection voltage limit is not exceeded, the BACnet specification in Clause "9.2.1 Medium" only mentions "shielded, twisted-pair cable."
BACnet devices added at a later date could be networked via IP Ethernet or
EIA-485. The current network spans all of the residences in the first phase of development and will accommodate further stages of development at the site.
