The Bus Terminals that have been used for years around the world in many industrial applications are making inroads into the field of intelligent building automation. Innovations in this particular field are currently extending Beckhoff’s “automation construction kit”.

New Bus Terminals for flexible building automation

Additions to the construction kit
In modern building automation, the air conditioning and heating technology is becoming increasingly powerful. A large number of sensors acquire temperatures, flow rates, pressures, the sunshine and many other physical magnitudes at various locations around a building. Actuators such as valves, regulating flaps, pumps and fans implement the commands from the “intelligent” building controller conveniently and with less power requirements. Connections between the controller, sensors and actuators are increasingly being implemented in the form of bus systems in buildings, as has been done for years in automation technology. This has many advantages: Assembly is easier, diagnostic and servicing facilities are improved, and the building’s fire load is significantly reduced. A large number of proprietary controllers and systems can be integrated if the infrastructure is developed starting with the planning phase and making consistent use of the latest technology. An entire building can be controlled and serviced over an Ethernet network; all the control tasks are handled by a PC-based platform.
Ethernet is an economical bus system, but nevertheless it is still generally not worthwhile to have a connection at every sensor, for cost reasons alone. The more economical alternative is to use a gateway through which a number of sensors and actuators are connected. The wide range of Bus Terminals provides the right range of capacity for the bus connection: More than 80 different Bus Terminals make an optimum interface available for every kind of signal. These nodes can include up to 255 Bus Terminals of any type at one Bus Coupler.

Providing shade with persistence
Beckhoff are offering solutions expertise to additional application fields through new Bus Terminals. This includes the direct control of power components such as the motors for blinds, servomotors and other 230 V AC actuators with right/left running functions. The KL2722 and KL2732 output terminals use a pair of power switches to control AC voltage from 12 V up to 230 V AC. The contact burn that often results from switching large inductances with high starting currents is not a problem for the KL2722. The switching element is a triac, and therefore free from wear. It has a high current carrying capacity of more than 40 A. The steady load capacity of a digital output is 1 A. Switching on as the voltage is transiting zero and switching off when the current is transiting zero ensure that the semiconductor switch is not excessively loaded, and protects the connected motor. Both Bus Terminals have a pair of mutually locked outputs, so that simultaneously running to the right and left is prevented. The KL2732 operates without power contacts using two potential-free switches.

Artificial sun with digital connections
Connecting to price-sensitive actuators in a controller system is a challenge for a universal gateway. A building’s illumination is typically implemented through a large number of devices. The price of a lamp, and therefore of the connection to a control system, is thus of great significance. The Digital Addressable Lighting Interface, DALI, is a simple bus system for building automation that transmits the signals for the digital operation of lighting devices. The lamp, sensor, button and switching elements are wired in parallel, and are linked through the controller. DALI offers two advantages: It is an economical interface, easy to install, and it offers fully digital connection of lamps and comparable devices. The new KL6811 Master Terminal closes the gap between the lighting controller and the lamp, and permits up to 64 DALI devices or DALI slaves to be connected.
The DALI Master is integrated into the Bus Terminal system as a normal Bus Terminal, and is therefore independent of the fieldbus in use.The DALI data is then passed on to the controller through the relevant Bus Coupler. When starting up, the KL6811 DALI Master performs the search for addresses, and supports the user in configuring his equipment. The 24 V supply unit integrated into the master terminal supplies the DALI slaves with the appropriate voltage; no other additional components are needed for operation. DALI is supported by most lighting control manufacturers. However other actuators, such as heating control valves or the motors for operating blinds are increasingly being put under digital control.

Digital alarm unit
The new KL1362 digital input terminal carries alarm signals in a very direct format. This terminal analyzes the input signal from break-in sensors using a current loop. Alarm contacts with a fixed resistance ratio can be monitored safely. In the process image, the state of the sensor is indicated by one bit each. A further bit reports short circuits or line interruptions. It is thus possible to use, for instance, a BC9000 Bus Terminal Controller with Ethernet connectivity, to transmit the alarm signals even over the Internet for remote diagnosis or remote alarm purposes. This can include the subsequent reaction, in the form of appropriate remote control signals used by actuators.

Power budget in the mains grid
The new KL3403 Bus Terminal for power measurement in three-phase networks allows power management to be implemented using any fieldbus system. The basic technical principle of the KL3403 Bus Terminal, which permits the measurement of all the relevant electrical data in a three-phase power supply network, is based on that of the KL8001 Power terminal. (for further information about the KL3403) The new Bus Terminals, along with the electronic terminal blocks already used in many applications, permit a powerful and extremely flexible building management system to be implemented. If extended by Beckhoff Industrial PCs and Control Panels, integrated solutions can be created reaching from the control station out to the operation of pump drives, or linked over the Internet, and including such features as seasonally dependent power management and daylight-responsive illumination. Because building management, in contrast to applications in factory automation, is characterized by the control of devices that are not highly time-critical, Ethernet and web-based control concepts represent very flexible and powerful platforms. Beckhoff’s control construction kit offers all the products, components and tools needed from one source.

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