WO1994024647A1

WO1994024647A1 - Control cubicle with data bus

Info

Publication number: WO1994024647A1
Application number: PCT/DE1994/000349
Authority: WO
Inventors: Joachim Bury; Josef Koller
Original assignee: Siemens Aktiengesellschaft
Priority date: 1993-04-13
Filing date: 1994-03-29
Publication date: 1994-10-27
Also published as: DE9305530U1

Abstract

Conventional control cubicles are fitted with switchgear which are endowed with a joint function only by interconnection via the control wiring. In the improved cubicle switchgear (1), control gear (2) and measuring instruments (3) are coupled via bus-compatible connecting components (4) to a databus (10) via which an event-controlled data exchange between the components (1, 2, 3) takes place. It is thus possible to provide a simple, flexible connection arrangement of the components (1, 2, 3) instead of the fixed and complicated control wiring.

Description

Control cabinet with data bus

The invention relates to a control cabinet with switching and optionally control and / or power supply units, which are connected to one another by control wiring.

Conventional control cabinets are equipped with switching devices which only get a common functionality by connecting them via the control wiring. The planning, wiring and testing of the functionality of the control cabinet means considerable costs due to the great need for time and material.

After the unpublished state of the art, a major advance was that the switching devices in

Control cabinet with a programmable logic controller

PLCs are controlled centrally and the control wiring of the

Switchgear takes place via a decentralized periphery. The decentralized periphery is connected via a serial bus to a microprocessor of the programmable logic controller. The control wiring between the

Switchgear simulated by a PLC program. The

The connection is set up sequentially in the program, which means a high degree of flexibility with regard to possible changes and considerable wiring savings due to implementation on a serial bus.

The invention has for its object to provide a switching system of the type mentioned above, which enables simple, flexible connection assignment of the switching devices and optionally of the control and / or measuring devices instead of a fixed and complex control wiring between the devices. This is achieved in that, instead of the control wiring, the switching devices as well as control and measuring devices are coupled via bus-compatible coupling links to a data bus, for example to a control area network, on which event-controlled messages are sent to the other messages on the data bus. send paired devices and through which they can receive messages that are intended for them.

The following advantages result with this embodiment. For example, auxiliary switching elements, such as terminal blocks and intermediate circuits, are unnecessary, which results in savings in terms of space and costs. The direct data traffic through event-controlled data exchange allows very fast reaction times even at low data transmission rates of approximately 100-500 kbaud. In addition, the control cabinet structure enables the functions, i.e. the devices can be set up in a distributed manner. Redundant device parts can thus be dispensed with. With the connection technology mentioned, the functions can be implemented much more economically in comparison to the cable harnesses previously required in conventional systems, which were relatively expensive in terms of acquisition and installation.

The connection of devices to the data bus can also be simplified in that the function of the bus-capable coupling elements is integrated in the switching, control and measuring devices, without the coupling elements themselves.

The software switching of functions during project planning and when testing the system is essentially achieved if a PC user interface is provided for the software connection of the switching, control and measuring devices.

With the aid of the software connection of the switching devices via the data bus, the control cabinet can be implemented as a closed system which functions autonomously without a programmable logic controller acting from the outside. Further advantageous designs of the control cabinet can be found in claims 6-8.

An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. Show it:

1 shows a control cabinet with switching devices coupled to a data bus, FIG. 2 shows the conventional coupling of the input and output of a current evaluation unit,

3 shows the coupling of a current evaluation unit via a data bus, with an integrated bus controller; FIG. 4 shows a diagram for status transmission via the data bus,

5 shows the data bus with multiple coupling elements and a view module, FIG. 6 connection techniques for connecting the data bus and for providing the power supply, FIG. 7 shows the use of a PC user interface for projecting and parameterizing standard functions.

As is known, conventional switchgear cabinets are equipped with switching devices which only get their common functionality when they are connected via control wiring. The switching devices are self-contained systems, consisting of inputs for sensors from a measured value processing, e.g. the determination of a temperature limit, operating and display elements as well as outputs, e.g. for relays.

In the new version of the control cabinet, switching devices 1, including the associated control devices 2 and measuring devices 3 for measuring-quantity acquisition and evaluation, as well as operating and display devices via bus-compatible coupling elements 4 to a data bus 10, for example a two-wire bus, are shown in FIG Data rail coupled. The usual control wiring omitted here. 1, an interface module 12 is connected to the data bus 10 and is connected via a serial transmission bus 15, for example a field bus, to a communication processor 14 of a programmable logic controller PLC. The interface module 12 has a microprocessor 11 with a control program which, with a corresponding design, allows the control cabinet to be operated as an independent function island, ie as a closed system. In addition, however, a higher-level intervention in the control of the switching 1, control 2 and measuring devices 3 is possible by means of the communication processor 14 which may be located remotely. This system structure enables higher-level systems, such as the PLC via the communication processor 14, to be relieved of control functions, the protective function decoupled on site and thus accelerated, and a defined behavior of the "system control cabinet" is possible in the event of a fieldbus failure. This means that in the event of a fieldbus failure, a transition to an undefined state is avoided and instead an orderly sequence of functions, such as shutting down motors, is possible.

Further control cabinets can be connected to the fieldbus 15 of any design according to FIG. 1 and controlled by the communication processor 14.

A data exchange between the control cabinets can also be achieved without a higher-level communication processor 14 by using a single two-wire bus 10 which is routed through the control cabinets and to which all switching devices 1 as well as control devices 2 and measuring devices 3 are coupled .

The data exchange between the switching devices 1, including the control devices 2 and measuring devices 3, is event-controlled and corresponds to the current flow or the switching state change in a conventionally wired system. This type of data exchange is known, for example, from the control area networks, which the person skilled in the art is familiar with from publications (see, for example, CAN - an alternative to the field bus from Lawrenz, Markt and Technik / Design und Elektronik, edition 18 of 09/05/89, p 64-68). Events are detected in the system, packaged in a message telegram and sent to the data bus. The addressees concerned receive the message and react. Instead of the control wiring, connections between devices are sent by software as messages between mailboxes with send and receive compartments defined by message numbers (FIG. 4).

FIG. 2 makes it clear that the connections of the inputs and outputs of the functions, here a current evaluation unit 23, no longer occur in the usual manner via switching elements 24, as shown in FIG. 2, but via a data exchange by direct connection to the data bus 10 according to FIG 3rd

An example of the communication in the control cabinet is explained with reference to FIG 4. It shows a current sensor B and a load switch A, which are each connected to a data bus 10 via a bus controller 16. The current sensor B detects an upper load, which requires a load separation by the load switch A. A current command from the current sensor B is then given to the load switch A by the bus controller 16 providing the current signal with a corresponding message number from the current sensor B and sending it to the data bus 10. The bus controller 16 from the load switch A recognizes on the basis of the message number the message "trigger" which is intended for it and then responds. In a corresponding manner, further current sensors C, D .. can address the load switch A and effect the "trigger" function. The function-assigned addressing, here for example the "trigger" function, means that several load switches on the data bus can also be addressed at the same time. The direct data traffic between the Bus subscribers allow very fast reaction times even at low data transmission rates of 100-500 kbaud.

The described mode of operation enables a distributed structure of functions which the switching devices 1 coupled to the data bus 10 perform. Furthermore, the use of the data exchange explained in the control cabinet means that the switching devices are tailored according to functional criteria and are optimized for interconnection in the control cabinet.

The new control cabinet allows redundant device parts to be dispensed with, since the reaction of a function, e.g. a load disconnector, even without control wiring and terminals between active and reacting devices.

5 shows the hardware structure of a data bus designed as a two-wire bus 10 with bus-compatible coupling elements 4. The two-wire bus 10 is integrated in a top-hat rail 13 onto which an interface module 12 and two coupling elements 4 are snapped, which in addition to the mechanical fastening, the electrical contacting required at the same time as the data bus 10 takes place. Conventional switching 1, control 2 and measuring devices 3 can be connected to the bus-compatible coupling elements 4. The coupling elements 4 contain e.g. a bus controller 16 for the status transmission task already explained above for FIG. 4. It is common to all participants connected to the data bus 10 that the protocol software is implemented in the hardware of the bus controller 16.

Shielded two-wire lines 5 or optical fibers 6 can be used as bus media (see FIG. 6). The latter provides a potential-free connection in the control cabinet with simultaneous immunity to interference from magnetic and electrical interference fields. The As shown in the drawing, bus media can also be mixed. It is thus possible to switch from a copper-based line structure to optical waveguide connection techniques and vice versa.

6 shows three line strands 25, each with four copper lines, which e.g. as mentioned in a top-hat rail. Two of the copper lines serve as data bus 10, the other two supply the power through a coupled power supply unit 8. The data bus connection between the upper and middle line 25 is potential-bound via a shielded line 5 and between the lower and middle line 25 potential-free via an optical fiber 6.

The optical fibers 6 are coupled to the two-wire bus 10 via converters 9. Switching devices 1 are connected to the middle and upper data bus 10 in a potential-free manner via optical fibers 6. In this case, a local power supply is necessarily provided for the switching devices 1. A switching device 1, e.g. a contactor combination with line switch, potential-connected via a shielded line 5. The power supply can take place here via the line.

The switching devices are wired to one another (software ringing) and switching values (softsetting) are set using a PC user interface, as is indicated in FIG. The configuration and parameterization of the control functions via the PC screen represents a significant relief compared to the requirements with the wiring that has been customary up to now.

According to FIG. 7, the standard functions are established by software-like connection using the user interface between the Terminals 22 of command transmitters 20 above the upper dashed line and terminals 22 of actuators 21, for example valves, contactors and indicator lights, are produced below the lower dashed line. The standard function can be, for example, a direct connection between the above-mentioned upper and lower terminals 22, a flasher unit 18 or a reversing drive control 19.

Claims

1.Control cabinet with switching (1) and optionally control (2) and / or measuring devices (3), which are connected to each other by control wiring, so that instead of the control wiring, the switching (1) and

Control (2) and measuring devices (3) via bus-compatible coupling links (4) to a data bus (10), e.g. a control area network are coupled, on which they send event-controlled messages to the other devices (1, 2, 3) connected to the data bus (10) and via which they can receive messages that are intended for them.

2. Control cabinet according to claim 1, d a d u r c h g e k e n n z e i c h n e t that one or more microprocessors (11) are connected to the data bus (10) with a control program that uses bus-compatible coupling elements (4) as inputs and outputs.

3. Control cabinet according to claim 1 or 2, so that the function of the bus-compatible coupling elements (4) is integrated in the switching (1), control (2) and measuring devices (3) without the coupling elements (4) themselves.

4. Control cabinet according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that a PC user interface is provided for the software connection of the switching (1), control (2) and measuring devices (3).

5. Switchgear cabinet according to one of the preceding claims, characterized in that an interface module (12) is coupled to the data bus (10), with the following features: • Function as gateway from a higher-level PLC with communication processor to bus-compatible coupling elements (4) as inputs and outputs.

• Function as connection of the (autonomous) control cabinet function group to a higher-level PLC via input / output coupling

6. Switchgear cabinet according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that switching (1), control (2) and measuring devices (3) further cabinet cabinets are coupled to the data bus (10).

7. Control cabinet according to one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the data bus is designed as an optical waveguide (10).

8. Switchgear cabinet according to one of the preceding claims, characterized in that the data bus (10) is integrated in a top-hat rail (13) onto which the bus-compatible coupling elements (4) are snapped, via which the switching (l), control (2 ) and measuring devices (3) are coupled to the data bus (10).