WO1995023395A1

WO1995023395A1 - A signal producing unit, e.g. a temperature sensor, to be coupled to a signal network

Info

Publication number: WO1995023395A1
Application number: PCT/DK1995/000083
Authority: WO
Inventors: Bent H. Jensen; Bjørn SAHL; Peter Nyegaard Jensen
Original assignee: Lanng & Stelman A/S
Priority date: 1994-02-24
Filing date: 1995-02-24
Publication date: 1995-08-31
Also published as: AU1806995A

Abstract

A signal producing sensor unit, e.g. a temperature sensor, is housed in a sensor housing together with equipment that enables the housing unit to be operatively connected with a fieldbus network without any other connection, i.e. without any cable mounting for current supply. The housing contains a storage capacity for energy currently picked up at small amounts from the very signal energy occurring at the signal network, as well as means for signalling the relevant measuring value briefly, when addressed from a central control unit.

Description

A signal producing unit, e.g.:.a temperature sensor, to be coupled to a signal network.

The present invention relates to a signal producing unit adapted for operative coupling to a signal network such as a so-called fieldbus network. As known, such a network can be used for establishing a selective signal connection between one or more control units and various types of measuring and adjustment systems. The signal network is a pure signal carrier, which is used for traditional communication, and which may sometimes be electrically dead and sometimes very much alive, e.g. with traffic of addressing signals from the control unit and responding reporting signals from various measuring units and other sensors etc.

The invention has its immediate background in the ship area, particularly in connection with large ships, where there is a need for measuring and remote reporting of different values, e.g. for temperature or pressure, with reference to places far away from the "electrically civilized" areas of the ship, i.e. at places to which it is expensive to establish cable connections. According to the invention it has been found possible to operate with a sufficient current supply through a tapping of energy directly from the signal network, i.e. directly from the occurring signal voltages. Normally, the sig¬ nals on the network will originate from conventionally current supplied control units and signal generators, and this provides a basis for the application of a num¬ ber of units which, with a very low current consumption, may be current supplied by the signal energy, inasfar as these units may exhibit a storage capacity sufficient for currently collecting a sufficient energy without the signals being unduly attenuated.

This collected energy of the signal units will be used, whenever a signal unit is actuated to transmit signals to the control unit, to provide, briefly, suf¬ ficient current for driving the signal network with all its associated units. The units, of course, should be provided with all required circuitry, and preferably they are also, physi¬ cally, designed as self-contained units, e.g. as a tem¬ perature sensor with both sensing equipment and electro¬ nics collectively housed in an apparatus box for plug connection with the laid-out signal cable. Thus, it will be sufficient to lay out this cable only.

In case of a temperature sensing unit the common apparatus box may typically be a standard DIN 43729 sensor housing, such that the signal unit is mechani¬ cally compatible with existing equipment; it will be appreciated that the advantages of the system are not obtained with associated counterdrawbacks, such as phy¬ sically enlarged units.

The single signal units will collect, by them¬ selves, the relevant measuring values and convert them into digital signals and transmit them to the signal network at request from the superior control unit.

As to hardware, the invention will comprise the entirety of interface to sensor, A/D converter, micro¬ processor, communication interface and voltage supply. Associated software may comprise a protocol and imple¬ mentation thereof in the sensor.

The protocol may exhibit facilities not only for the transmission of digital measuring values, but also for the set-up of alarm limits (max./min. level) for event control of the transfer of the measuring values. Moreover, the protocol may enable a software controlled adjustment of the sensor, e.g. for span, zero point, correction of linearity, etc.

The invention may be applied in any relevant con¬ nection, but in particular, as mentioned, where it is expensive or for other reasons undesirable to arrange for external voltage supply.

Claims

C L I M S :

1. A signal producing unit, in particular a measur¬ ing unit having a sensor in an apparatus housing adapted for operative connection with a signal network such as a so-called fieldbus network, characterized in that the unit comprises a storage capacity for currently taking up a small, but permissible part of the signalling ener¬ gy occurring on the network, sufficiently to make the unit self-supplying with energy to the extent that it may be operative during short intervals of time without any separate, external voltage supply.

2. A unit according to claim 1, characterized in that it is even physically unitary, i.e. appearing as an apparatus housing or sensor box, e.g. of the type

DIN/IEC 751, containing both the sensor, the storage capacity and other equipment required for active opera¬ tion solely with connection to the signal network.