The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 19, 2015
Filed:
Jul. 10, 2008
Antoine Simon, St. Louis, FR;
Antoine Simon, St. Louis, FR;
ENDRESS + HAUSER FLOWTEC AG, Reinach, CH;
Abstract
A fieldbus unit for connection of a field device to a fieldbus comprising two conductors is designed to transfer a signal via the fieldbus by modulation of an electrical current drawn by the field device. The fieldbus unit comprises: an electrical current control transistor, through which the electrical current drawn by the field device flows, wherein the electrical current drawn by the field device is controlled via a base current of the electrical current control transistor; a bipolar transistor, via whose emitter-collector, electrical current path the base current for driving the electrical current control transistor flows; as well as an electrical current controller, which produces an electrical current control signal for controlling the electrical current drawn by the field device. The base of the bipolar transistor is placed at an essentially constant potential, which is so selected, that the bipolar transistor supplies the electrical current control transistor a base current sufficient for start-up of the field device, when the electrical current controller is not supplied with electrical current and delivers no electrical current control signal. The electrical current controller feeds the electrical current control signal via the emitter-collector, electrical current path of the bipolar transistor.