Bms - Lennox CLIMATIC series User Manual

COMMUNICATION

BMS

Function
BMS (building management systems) are systems for the integrated management of all the technological functions of a building,
including access control, safety, fi re détection, lighting, intelligent elevators, and air-conditioning. The resulting advantages of such
solutions are simpler and more effi cient management of the building from a single control station, reduction in running costs, possibility
of statistical analysis of all data, immediate identifi cation and response to faults and alarms. This amply justify the little extra cost of
the air-conditioning unit BMS connectable. Today not only the quality and the reliability of the instruments are important, but also the
degree of external connectivity they can offer.
Description
The communication bus is connected on CLIMATIC's serial card board on the BM. A star connection is not recommended, for an
optimum operation, it is advised to connect a maximum of two cables per unit. In case of RS485 bus, a resistance of 120Ω 1/4W can
be connected on the last unit between the terminals + and -.
The CLIMATIC offers different possibilities of BMS protocol:
• Modbus RTU,
• Trend,
• Bacnet,
• Lon Works.
Modbus is a serial communications protocol published by Modicon in 1979, and has become a standard communications protocol in
industry. It is now the most commonly available method to connect industrial electronic devices.
Controllers communicate using a master–slave technic, in which only one device (master) can initiate transactions (called 'queries').
The other devices (slaves) answer by supplying the requested data to the master, or by taking the action requested in the query.
CLIMATIC RT_UNITARY-IOM-1508-E
Max = 1000 m
• 37 •