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Building automation control tecnology

Standard communication protocols


All products designed by e-Controls are using standard protocols complying the Open Systems concept. Company strategy is based in providing compatible products to the market, easy to integrate without the need of using complex gateways that cause undesired communication problems on the facilities.

Open Systems based installations provide the possibility to integrate e-Controls products with other manufacturer devices, ensuring the interoperability concept and making it grow in the future without restrictions.

Different protocols and technologies used in the e-Controls products are described briefly below.

Products for HVAC, indoor lighting and street lighting are using the EN14908 standard, more known as LonWorks®. All products are complying with the interoperability standard defined by the LonMark® organization ensuring the possibility to exchange information with other manufacturer devices. Used in TP/FT-10 twisted pair network and in PowerLine network, the devices can send information through the bus to communicate to other devices in the same network.

LonWorks® is defined by the ISO/EIA14908 standard and it is divided in four parts:
EN14908-1: Part 1. Protocol definition
EN14908-2: Part 2. Twisted pair communication channel
EN14908-3: Part 3. Mains electrical network (PowerLine) communication channel
EN14809-4: Part 4. IP (Internet Protocol) communication channel

The technology is also standardized in the U.S.A. undr the ANSI/EIA-709 or CEA-709 standard.

In a LonMark® channel the data transmission can be started by any device on the network, because of the CSMA/CA access media protocol that makes any device start the conversation with any other on the network. Different physical channels are defined on the standards. Depending on the channel type a number of devices can be connected on the channel. On the twisted pair channel, commonly named TP/FT-10 (twisted pair / free topology) can coexist up to 64 Lon devices. Another configuration called Link Power, where the physical channel carries power supply for the devices (nodes) and data on the same existing wire. For this type of channel, the maximum number of devices can be up to 127 devices. On the PowerLine channel (using the mains electrical wire) the maximum number of devices is defined on 127 nodes, but it must be taken into account that this channel has no physical limitation and what really makes the segmentation is the logical definition of the devices in a subnet.

In a LonMark network the maximum number of devices in a network is practically unlimited (248).

BACnet is a communication protocol for network control and automation in buildings. The protocol is standardized in America under the ASHRAE/ANSI 135 standard and in Europe under the ISO 16484-5. Its principal function is to control all the HVAC services of the building.

The BACnet protocol is using the Ethernet cannel as a transmission media to communicate different subsystems or independent buildings and manage the installation from the BMS (Building Management System) point of view. It is also defined the possibility to use an RS-485 channel called MS/TP mainly used in building bus field communication devices like thermostats and controllers.

Modbus is a de-facto standard communication protocol widely used for energy meter monitoring and control and also input/output devices in a network. Based on a Master/Slave architecture where a device called Master is taking the lead on the network asking the Slaves forming the device network. A question/answer protocol where different codes corresponding to commands are defined is used to monitor the remote devices. In a Modbus based network a Modbus master must be defined, but also the Slave devices.

Modbus protocol can be used even in the Ethernet channel (Modbus/TCP) than RS-485 channel (Modbus/RTU). In the RS-485 channel the devices must be physically connected to the network as in the RS-485 standard is defined.

It is also possible to use the Modbus protocol over other physical channels like RF (radiofrequency), RS-232, etc.

M-BUS (Meter-Bus) protocol is a low cost communication bus mainly used to read information from energy, water and gas meters. The protocol is standardized under the standard EN 13757-2 (physical and link layer) for the physical channel and under the EN 13757-3 standard (application layer) for the protocol/application.

The physical cannel is defined as a galvanic isolated wire, making it ideally for noisy electromagnetic environments like industry, but also widely used in homes and buildings.

The protocol is based in an easy question/answer communication where the Master asks the Slave the information requested. The system is designed to consume as less energy as possible because of the meters are usually powered with batteries.

In an M-BUS channel up to 250 devices can be on the same wire.

DALI is a digital communication interface standardized under the ISO60929 (EN60929) and more recently the new EN62386 version. It was designed for electronic ballast remote control on luminaries. The communication protocol includes a command table where luminaries can be monitored and controlled remotely, making it possible to switch on, off and dim at a desired level any kind of luminaire. Different group functions are possible to do a global light control over different luminaries with a single command. At the same time it is possible to know if the lamp is working or it is failed, to inform at any time the building management system of the facility.

Up to 64 devices can be in a same DALI channel and the communication is working as master/slave. Thus an arbiter or Master must be on the channel and is the responsible to start a transaction to the ballasts. Every ballast is including a unique address on the bus that can be identified and can indentify which message is for it, answering at any time when the message goes to it.

The DALI Master device must include a power supply to provide a voltage range from 9Vdc to 22Vdc and a maximum current up to 250mA. Then, the DALI channel is carrying a voltage level (with polarity) but the receivers or ballasts include several components that makes them polarity insensible and no special precautions are needed to connect the ballast to the bus.

Logo e-controls Electronic Intelligent Controls, S. L. | C/Murcia 35F | 08830 Sant Boi de Llobregat | Barcelona | Spain | Tel.:+34 93 652 55 21 | Fax +34 93 652 55 22

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