Bus terminal

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A bus terminal is a further developed terminal block that can process different analog and digital input and output signals. It is housed and wired simply and compactly like a conventional terminal block, but in contrast to the terminal block it has intelligent electronics.

construction

A bus terminal unit usually consists of a bus coupler and a large number of electronic terminal blocks. The bus coupler has an interface to a fieldbus and in this way integrates the bus terminals into the control system. Bus couplers with their own intelligence are called Bus Terminal Controllers. They already have PLC functionality on a small scale and can process smaller control tasks in a decentralized manner without the intervention of the control computer.

The communication between the bus coupler and the individual bus terminals usually takes place via an internal terminal bus. The connection between the Bus Terminals is wireless via contacts.

A bus terminal unit is installed in a switch cabinet on a DIN top-hat rail. Modern systems allow Bus Terminals with a wide variety of signal types to be arranged in a row. The exchange of individual Bus Terminals or the subsequent expansion of the Bus Terminal unit is also possible with these systems within the limits of the physical system. Bus Terminals are usually put together sorted according to signal type, which is beneficial for clarity in a control cabinet.

Areas of application

Bus Terminals are used wherever analog and digital inputs and outputs (I / Os) are to be wired and transmitted to a controller via a fieldbus. The main task is to record the multitude of different signals, e.g. B. on a machine, to bundle and forward to the controller via a uniform bus signal or to pass on commands from the controller to the actuators. By using master terminals within a bus terminal line, it is possible to transfer signals from sub-levels that communicate with each other via another fieldbus signal to the higher-level fieldbus. In addition, with special terminals it is possible to control drives directly from the terminal network.

The bus terminal was originally developed for industrial automation technology. Their main area of ​​application is mechanical and plant engineering. As a result of the ongoing development in the field of building automation, Bus Terminals are now also used in the automation of buildings. In the meantime, special terminals have been developed for this area, which are geared to the special requirements in building automation. These include B. dimmer terminals for controlling lighting equipment, triac terminals for controlling blind motors and communication or master terminals, which integrate the bus systems common in building technology into the higher-level bus system.

Signal types

There are bus terminals a. for the following input and output signals:

Digital signals

  • DC: 5 V, 24 V, 48 V, 120 V
  • AC: 120 V, 230 V, 400 V
  • NAMUR
  • Binary signals
  • PWM
  • Stepper motor
  • DC motor output stage
  • safe signals

Analog signals

  • 0–2 V, 0–10 V, +/- 2 V, +/- 10 V
  • 0 / 4-20 mA
  • Thermocouples
  • Resistance sensors, bridges
  • oscilloscope
  • Pressure measurement
  • Performance measurement
  • Distance / angle measurement

Field buses

Bus Terminals can be used in combination with a large number of bus systems. There are now bus couplers u. a. for the following field buses: Profibus , Profinet IO , Ethernet Powerlink , EtherCAT , CANopen , Lightbus, Interbus , DeviceNet , ControlNet , CC-Link , Modbus , Fipio, SERCOS , SERCOS III , RS232 , RS485 , Ethernet TCP / IP, USB , AS -Interface , DALI / DSI , EIB and LON .

swell

  • Bus Terminal Technology - A Technical Revolution ... , in: elektro AUTOMATION, 04/2005.
  • Manufacturing and machine automation : Bus terminal system , in: etz Elektrotechnik + Automation , 2005.
  • Bus Terminals for high-precision control processes , in: PC Control, 03/2004.