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Fieldbus unit for a two-conductor fieldbus

A fieldbus and field device technology, applied in general control systems, program control, electrical components, etc.

Inactive Publication Date: 2010-08-11
ENDRESS HAUSER FLOWTEC AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Another disadvantage is that the bypass circuit must be able to handle higher bus voltages, e.g. up to 35V according to IEC61158-2 standard chapter 12.7.2, which also means additional circuit complexity

Method used

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  • Fieldbus unit for a two-conductor fieldbus
  • Fieldbus unit for a two-conductor fieldbus
  • Fieldbus unit for a two-conductor fieldbus

Examples

Experimental program
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Embodiment Construction

[0025] figure 1 A Profibus network is shown with three field devices F1, F2, F3, a control unit SPS and another superordinated unit WS1, which exchange data via a fieldbus F.

[0026] figure 1 The Profibus network shown can be, for example, an overfill prevention device for a liquid storage tank. The field device F1 measures the level in the container. Field device F2 is a valve and controls the flow of liquid from the container. A field device F3 is also provided as a limit switch, which detects the maximum fill level in the container. The control unit SPS may for example be a programmable logic controller in which a control program controls the level in the container. The control unit SPS is the Profibus master device, and the field devices F1, F2, F3 are Profibus slave devices.

[0027] A fieldbus comprising two conductors is used in particular for linking field devices in hazardous areas, for example areas at risk of explosion. The individual field devices do not hav...

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PUM

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Abstract

The invention relates to a fieldbus unit for connecting a field unit to a fieldbus comprising two conductors, said fieldbus unit being designed to transfer a signal via the fieldbus by modulating a current received by the field device. The fieldbus unit comprises a current control transistor through which the current received by the field device flows, the current received by the field device being controlled by means of a base current of the current control transistor, a bipolar transistor, the base current flowing via the emitter-collector current path of said bipolar transistor to trigger the current control transistor, and a current controller generating a current control signal for controlling the current received by the field device. The basis of the bipolar transistor is a substantially constant potential selected so that the bipolar transistor provides base current to the current control transistor sufficient for starting up the field device when the current controller is not supplied with current, and does not provide a current control signal. The current controller feeds in the current control signal via the emitter-collector current path of the bipolar transistor.

Description

technical field [0001] The invention relates to a fieldbus unit according to the preamble of claim 1 and a fieldbus according to claim 9 . Furthermore, the invention relates to a fieldbus unit according to the preamble of claim 10 and a fieldbus according to claim 18 . Background technique [0002] In process automation technology field devices are frequently used which serve to detect and / or influence process variables. Examples of such field devices include level measuring instruments, mass flow measuring instruments, pressure and temperature measuring instruments, etc., which act as sensors to detect the corresponding process variables, ie level, flow, pressure and temperature. [0003] Used to influence process variables are actuators, such as valves or pumps, by which the flow of a liquid in a pipeline or the level in a container can be changed. [0004] In principle, all devices that are used in the vicinity of a process and provide or process process-related informa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G05B19/042
CPCH04L12/40045H04L2012/40221G01D21/00
Inventor 安托万·西蒙
Owner ENDRESS HAUSER FLOWTEC AG