EP0387191B1 - Method for connecting a programmable control device with operating and/or display elements, and circuit arrangement for a programmable control device - Google Patents

Abstract

A memory-programmable control device (2) is connected via serial data lines (8a, 8b) to an allocated operating and display device (9). The parallel output lines (25) of the memory device (2) are connected to a register (24), from which the data records intended to control the display elements (12) are read out in series and forwarded to the display device (9b). The control signals supplied from the operating elements (11) are fed as serial data records to an input shift register (16), the memory contents of which are entered cyclically and in parallel via connections into a result register (21), the output lines (23) of which are connected in parallel to the inputs of the control device (2). <IMAGE>

Description

In house technology, especially in larger buildings such as Hospitals, different field devices, i.e. electrical consumers installed. It can e.g. act as actuators, fan motors, lighting devices and the like. The connection lines of these field devices are usually brought together in control cabinets at a central point in the building and are fed there by corresponding control devices, which can also be part of a control loop.

The control of the field devices according to the respective control output of a control device is usually done conventionally via relays, contactor relays and coupling relays.

To operate the control devices, at least one operating device, such as a control panel, is provided with a plurality of operating elements such as switches. In addition, a plurality of display elements is generally required, with which the switching status of field devices, parameters of the control device and other information can be displayed. For the electrical functional sequence, it is necessary for each of the operating elements (control switch, pushbutton) and the display elements (signal lights) to be connected to the control device via a large number of electrical connecting lines.

The use of programmable logic controllers ("PLC") can reduce the effort, especially for the control units (contactor relays, relays, mechanical counters, timing relays, flashing relays and the like), but this does away with the wiring problem in the area between the operating elements and the display -Elements and control device rather reinforced. The more powerful the control device, the larger and more diverse the need for operating elements and display elements. For each of these elements, a separate, i.e. parallel input and a parallel output must be provided on the control device (PLC). This leads to high costs for wiring the display and operating elements, makes subsequent modifications of the switching arrangement difficult and also prevents the operating and display elements from being arranged spatially separate from the control device without the wiring expenditure increasing immeasurably.

The object of the invention is to avoid the disadvantages of the known, in particular to create a method and a circuit arrangement for a programmable control device, by means of which the functional connection of the control device (PLC) and operating device or display elements can be produced.

According to the invention, this is achieved primarily with a method according to claim 1 or a circuit arrangement according to claim 3.

Instead of the conventional switch and display elements with a direct galvanic connection to the control device, the invention therefore selects a method or a circuit arrangement in which the status of the operating elements is queried cyclically and the information obtained is cyclically can be read into a shift register in signal groups. After the completion of such a cycle, the state of each individual memory of the shift register corresponds to the state of the associated control element, so that after reading in in a second cycle, the signals can be transferred in parallel from the individual memories into a result register with a corresponding number of memory locations. The outputs of the memory locations of the result register are on the input side at the parallel control inputs of the programmable control device, so that there is a constant signal at each input which corresponds to the state of an assigned operating element. By continuously transmitting such signal groups and repeating the cycle, it is evident that the state of the result register can always be updated such that the PLC is controlled on the input side in accordance with the position of the operating elements. Cycle times of, for example, 5 ms to 10 ms have proven successful. Depending on the number of operating elements and the required transmission speed, any number of shift registers can be provided, each of which represents a certain number or a certain group of operating elements. In this way, both the circuit complexity in the operating device and the number of connecting cables between the PLC and the operating device or display device are drastically reduced.

Shift registers and result registers can be designed as additional devices for conventional PLCs and connected to their parallel inputs. Alternatively, it is of course also possible to convert the signals yourself in a suitably designed PLC.

In the same way, the invention provides for the output signals of the PLC for the display elements to be serially transmitted and converted into corresponding registers. To the clocked A clock must be provided for the transmission and reading in of the signals, a clock line being provided for synchronizing the transmission between the display device or operating device and the PLC. It is expedient if the operating and display device has separate memories for the operating elements and the display elements.

Figur 1

die schematische Darstellung einer Schaltanlage mit einer Steuervorrichtung und einer Bedienungs- und Anzeige-Einrichtung,

Figur 2

die schematische Darstellung der Zusammenschaltung einer Bedienungs- und Anzeige-Einrichtung mit einer Steuervorrichtung mit den Merkmalen der Erfindung,

Figur 3

ein Blockschaltbild zur Darstellung des Eingabe-Schieberegisters und des Ergebnisregisters, und

Figur 4

ein Blockschaltbild zur Darstellung des Ausgaberegisters.

The invention is explained in more detail below in an exemplary embodiment with reference to the drawings. Show it:

Figure 1

the schematic representation of a switchgear with a control device and an operating and display device,

Figure 2

the schematic representation of the interconnection of an operating and display device with a control device with the features of the invention,

Figure 3

a block diagram showing the input shift register and the result register, and

Figure 4

a block diagram showing the output register.

According to FIG. 1, a programmable logic control device 2 (PLC) is provided in a control cabinet 1 (not shown). The PLC controls a number of power contactors 4 in a known manner, which are connected via a terminal strip 5 to consumers, not shown, such as ventilation motors, lighting devices and the like. Motor protection switches 3 are provided as protective devices for motors.

Fuses 6 are provided to protect the various circuits.

The PLC 5 controls the various consumer or field devices 7 connected to the terminal strip 5 in a programmable manner.

On the input side, the PLC is connected to a combined operating and display device 9 via a connecting line 8 (data bus). The operating and display device 9 is arranged in the door 10 of a control cabinet, as is indicated schematically in FIG. 1. In addition, a remote control panel 9a can be provided.

As can be seen from the schematic illustration in FIG. 2, the operating and display device 9 consists of a plurality of operating devices 9a and display devices 9b. In the exemplary embodiment, each of the operating devices 9a has 8 illuminated pushbuttons 11 as operating elements. A specific function of the PLC 2 or a function of one of the field devices 7 can be assigned to each of the illuminated pushbuttons 11. The number of illuminated pushbuttons 11 per operating device 9a and the number of illuminated indicators 12 per display device (9b) depends on the complexity of the system and the functions that the PLC 2 is to perform. Any other switching elements can of course be used instead of the illuminated pushbuttons 11.

According to FIG. 2, each of the display devices 9b has sixteen indicator lights 12 as display elements. The indicator lights 12 can each be assigned to a specific operating state of the PLC or the field devices 7. The control devices 9a and the display devices 9b are connected by means of a bus board (not shown) to a system card 13 which has an interface 14 for connecting the line 8. Line 8 has eight cores, one of the cores being a clock line with which the clock frequency of the PLC is synchronized with the clock frequency of the operating and display device.

As shown schematically in FIG. 3, each sixty-four illuminated pushbuttons 11 are connected to an arrangement 15, in which signals are stored which correspond to the respective position of one of the illuminated pushbuttons 11. In the frequency of the clock, which is synchronized on the line E0 between the arrangement 15 and an input shift register 16, all information stored in the arrangement 15 and an instantaneous value of the Illuminated pushbutton 11 correspond. The input shift register 16 is fed with data via an input 17. As indicated, the input shift register 16 has sixty-four memory locations C1 through C64. The data applied via the input 17 are "shifted" into the shift register 16 in time with the clock line E0 until a data group of sixty-four items of information - corresponding to the switching positions of the sixty-four illuminated pushbuttons 11 - is in the shift register 16. The data line 8a is an additional line to the wires labeled E0 to E5, which connect the interface 14 to the PLC 2 (FIG. 2). Analogously to FIG. 3, each of the wires can connect an arrangement 15 to an input shift register 16, so that the information from sixty-four operating elements is read into the memory locations of an input shift register 16 via a data line.

As shown schematically in Figure 3, the lines E1 to E5 are also connected to an evaluation logic 18, which is also connected to the clock line E0. The evaluation logic 18 determines the start and the end of the transmission of data groups on the line 8a. As soon as all sixty-four information items have been read into the input shift register 16, the evaluation logic 18 determines the end of a transmission cycle. The input 20 of a result register 21 is driven via a control line 19, which now takes over the information pending at the storage locations C1 to C64 of the input shift register 16 in parallel via parallel connecting lines 22. The information which corresponds to the switch positions of the illuminated pushbuttons 11 remains in the result register 21. They are connected to the input of the PLC 2 via output lines 23. At the same time, a new transfer of a group of sixty-four information via the data line 8a and the input 17 into the input shift register 16 begins. During the time of the transfer, the information from the previous cycle remains stored in the result register 21. Only when the shift register 16 has taken over a complete group of sixty-four pieces of information again during the subsequent cycle, is the result register 21 actuated again by the evaluation logic 18 and the new data record is taken over the connection 22 in parallel. Due to the high clock frequency on the clock line E0, the cycle time is only a few ms, so that the result register 21 is supplied with current status information at very short time intervals and current switching data is present at the input of the PLC with a negligible delay.

Of course, the number of memory locations in the input shift register 16 can be increased or decreased depending on the requirement profile of the overall arrangement, and the number of data lines can also be adapted to the requirements of a system. The query of the illuminated pushbuttons 11, the temporary storage of the information and the reading out into the data line 8a is controlled in a known manner by a microprocessor and requires no further explanation. It is only important that the arrangement 15 and the input shift register 16 or the result register 21 are synchronized via the clock line E0 in such a way that a correct assignment of the data to the individual illuminated pushbutton 11 and a corresponding "storage" in one of the memory locations of the input shift register 16 are guaranteed.

FIG. 4 shows an output shift register 24, which is located at the outputs of the PLC 2, which control the indicator lights 12. In conventional systems, each of the output lines 25 is connected to one of the indicator lights 12, while in the present case the output lines 25 are located at the inputs of the memory locations of the shift register 24. Analogous to the transmission cycles to the input shift register 16 or the result register 20 in FIG. 3, the output shift register 24 is driven by a control circuit (not shown) via a clock line E0 and a control line 26. In the same transmission cycle of 5 ms as for the input shift register 16, the output shift register 24 is polled, and the signals present on the lines 25 are converted into serial data groups which are passed via a data line 8b to an arrangement 27 in which the incoming ones Data are assigned to the individual indicator lights 12 and stored. The transmission with short cycle times ensures that the switching state of the indicator lights 12 corresponds practically without delay to the signals output by the PLC to the output lines 25. The conversion of the signals arriving in series via the data line 8b into signals available in parallel for the control of the indicator lights 12 is preferably carried out in the arrangement 27 analogously to the functioning of the input shift register 16 and result register 21. As shown in dashed lines in FIGS is indicated, the elements required for the data conversion, namely the evaluation logic 18, input shift register 16, result register 21 and output shift register 24, are combined in a schematically indicated input part 2a, which is part of the PLC 2. Of course, it is also conceivable to design the input part 2a as an independent device with its own power supply, etc. and to establish a connection by means of the output lines 23 and 25 to the corresponding outputs of a conventional PLC.

Claims (6)

1. A method of operatively connecting an electronic programmable control apparatus (2) provided with a data store, for equipment in buildings, to a plurality of operating elements (11) and/or display elements (12), characterised in that the signals produced by the operating elements (11) are interrogated and serially read in signal groups by way of at least one line (8a) into a shift register (16) provided with individual storage locations in a first cycle, that after the reading-in operation in a second cycle the signals are transferred in parallel from the individual storage locations of the shift register (16) into a result register (21) with a corresponding number of storage locations, and that the control inputs of the programmable control apparatus (2) are actuated by the outputs (23) of the storage locations of the result register (21).
2. A method according to claim 1 characterised in that the output signals of the programmable control apparatus (2) are applied in parallel to the inputs (25) of a shift register (24) which is provided with a plurality of storage locations, and that the items of information stored in the shift register (24) are cyclically passed as a serial data set to an arrangement (16) for actuation of the display elements (12).
3. A circuit arrangement for a programmable control apparatus (2) for equipment in buildings for the control of field devices (7) having at least one display device (9b) for displaying a plurality of operating conditions and at least one operating device (9a) for carrying out a plurality of operating procedures, wherein the control apparatus has parallel operating inputs (23) and display outputs (25) respectively for connection to operating elements (11) of the operating device (9a) and to display elements (12) of the display device (9b) respectively, characterised in that the inputs (23) and the outputs (25) respectively are connected to at least one respective arrangement (16, 21, 24) for the conversion of serial input data into parallel input data for the inputs (23) and for the conversion of parallel output data at the outputs (25) into serial data groups respectively.
4. A circuit arrangement according to claim 3 characterised in that the inputs (23) of the control apparatus (2) are connected in parallel with the outputs of a result register (21), that the storage locations of the result register are connected in parallel with the storage locations of a shift register (16), that the serial input (17) of the input shift register (16) is connected by way of a data line (8a) to the output of the operating and display device (9), and that an evaluation logic means (18) for cyclic actuation of the result register (21) is connected thereto in such a way that after the respective operation of serially reading a data set into the input shift register (16) the data are transferred in parallel into the result register (21).
5. A circuit arrangement according to claim 3 or claim 4 characterised in that the output signals of the control apparatus (2) are applied to the parallel inputs of an output shift register (24), and that the serial output of the shift register (24) is connected to the operating and display device (9) by way of a data line (8b).
6. A circuit arrangement according to one of claims 3 to 5 characterised in that the shift registers (16, 24), the result register (21) and the evaluation logic means (18) are combined in an input circuit (2a) which is a component of the control apparatus (2).

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