EP1037234B1 - Safety switching circuitry - Google Patents

Abstract

The safety cut-out switch has at least 2 series opening switches (12a,12b,12c) coupled to a microprocessor evaluation unit (11), for providing a safety signal, e.g. an alarm or cut-out signal, upon opening of at least one of these switches, which each have a code signal generator (13a,13b,13c), coupled to the evaluation unit via a common diagnosis line, for providing a code signal identifying the operated switch.

Description

The invention relates to a safety switching arrangement according to the preamble of claim 1.

It is already known (W. Gräf, Maschinensicherheit, Hütig-Verlag 1997, Pages 108 - 111), in the area of safety technology, safety switches daisy chain to protect danger spots. This is e.g. used for emergency stop circuits in transfer lines and on conveyor belts. To the respective location of the triggered in the event of an actuation Safety switches are to be determined on each safety switch Diagnostic contacts provided with the opening of the safety switch be operated and by individual lines with the evaluation unit are connected. Due to the need for a cable connection The wiring effort for each diagnostic contact with the evaluation unit this known safety switching arrangement high. Installation and commissioning are complex. On the evaluation unit are numerous PLC (programmable logic controller) inputs required.

The object of the invention is a safety switching arrangement to create the genus mentioned at the beginning, with a considerable reduced wiring effort and easy to install and to be put into operation.

To solve this problem, the characteristics of the characteristic part of claim 1 provided.

The idea of the invention is therefore to be seen in the fact that each opening switch triggered a characteristic code signal when opened and is common to all or more opening switches Line of the evaluation unit is supplied. In this way, the previously required star-shaped wiring of the opening switches provided diagnostic contacts; it is through serial concatenation of diagnostic signals replaced. Additional PLC inputs on the evaluation unit can be avoided in this way.

Activation of the code signal generator associated with each opening switch expediently takes place according to claim 2.

The transfer of the code signals generated by the code signal generator to Evaluation unit can take place according to one of claims 3, 4 or 5.

While in the embodiment according to claim 3, the wiring effort is particularly low, the embodiment according to claim 4 the advantage of a strict separation of diagnostic and safety circuit, which leads to simpler evaluation logic in the evaluation unit.

Another way of generating the code sequence or code signal according to claim 5 is that the mechanical force at Press the safety opening switch to generate a short one electronic signal is used. In this case there is an additional one Power supply and the necessary wiring effort dispensable. It is only necessary that the safety opening switch is modified accordingly.

Each code signal generator therefore sets when the assigned safety opening switch is actuated a unique code sequence either the safety path formed by the line sections or on the additionally provided single diagnostic line. The safety path (Safety line and safety line sections) is normal, closed state closed.

An ASICS or microprocessor can have a unique code sequence or a unique code signal can be programmed, which one is issued in the event of actuation of the opening switch. This is the special power supply according to claim 6 expedient. This can possibly also from the safety path or the diagnostic line be won. Commercial safety switches can still be used are used, which then with a corresponding additional Electronics must be equipped.

In addition to the safety and, if applicable, diagnostic line for the In the event that the generators require an externally supplied voltage, the features of claim 6 useful.

The code signal generators are preferably designed according to claim 7. An advantageous development of this embodiment can be seen Claim 8.

The code signal of the code signal generators can either according to claim 9 thereby being applied to the safety or diagnostic line, that the closing switch in an activation line of the microrprocessor be introduced and the signal output constantly with the safety or diagnosis line is connected, or in that the microprocessor is constantly activated and the closing switches are arranged in the signal output become.

According to the invention, only the connections are preferably on the evaluation unit provided according to claim 10.

The connection test-out of the evaluation unit is expedient issued a test signal for error detection, which on the connection Test-In is read back. If an opening switch is actuated the data flow is interrupted. At the same time, the closing switch closed, whereupon the one generated by the assigned code signal generator Code sequence modulated onto the safety path or the diagnostic line becomes. The Test-In or Diagnostic-In connection recognizes this code sequence and assigns it to the corresponding opening switch via a Connection table to which is created during installation. Any safety switch receives a unique and unique assignment from the factory Code sequence.

The invention has the advantage that the star-shaped wiring of the diagnostic contacts omitted and thus the cabling effort on the safety path can be reduced. Beyond that no individual Diagnostic inputs on the evaluation unit required. this means Additional savings in the area of decentralized inputs and outputs. The evaluation of test signals is already in intelligent controls or decentralized inputs and outputs, so that there is no major additional Development effort is necessary.

The invention is not only limited to emergency stop switching arrangements, but ultimately also when daisy chaining all outputs with contacts of security devices applicable, e.g. with safety gate switches, contactless protective devices, position switches, two-hand controls Etc.

Redundant security paths are used to achieve higher security classes used. The circuit does not have to be expanded for this. Installation and commissioning are simplified due to the line savings as well as through the use of existing system configuration tools, like PC tools.

• Adressierung der einzelnen Busteilnehmer;
• Vermeidung der Datenkollision durch aufwendige Telegrammverfahren;
• Verwendung von speziellen ASICS zur Busanschaltung.

The invention does not represent a bus system and thus avoids the following disadvantages inherent in a bus system:

• Addressing of the individual bus participants;
• Avoidance of data collision through complex telegram procedures;
• Use of special ASICS for bus connection.

Figur 1

eine Ausführungsform der Erfindung, bei der auf eine besondere Diagnoseleitung verzichtet ist,

Figur 2

eine weitere Ausführungsform mit einer besonderen Diagnoseleitung und

Figur 3

ein praktisches Ausführungsbeispiel eines bei der erfindungsgemäßen Sicherheitsschaltanordnung verwendbaren Generators.

The invention is described below, for example with reference to the drawing; in this shows:

Figure 1

an embodiment of the invention, in which a special diagnostic line is dispensed with,

Figure 2

a further embodiment with a special diagnostic line and

Figure 3

a practical embodiment of a generator that can be used in the safety switching arrangement according to the invention.

According to FIG. 1, an evaluation unit 11 has a test-in connection 23, a test-out connection 24 and a voltage supply connection 25 on.

The test-in connection 23 leads over a first safety line section 16a to a first safety opening switch 12a, then via a second security line section 16b to one second safety opening switch 12b and then continue via one third security line section 16c to a third security opening switch 12c and from there via a safety line return 16 back to test-out port 24. This way a safety path when the opening switches 12a, 12b, 12c are closed 16a, 12a, 16b, 12b, 16c, 12c, 16 created, which normally closed and when one of the opening switches 12a, 12b, 12c responds opens and thus the evaluation unit 11 a fault in the area of the open Opening switch 12a, 12b or 12c signals.

Each opening switch 12a, 12b, 12c is a closing switch 17a, 17b, 17c associated with the opening of the associated opening switch 12a, 12b, 12c closes. The closing switches 17a, 17b, 17c are on the one hand with a code signal generator 13a, 13b, 13c and on the other hand with the input 14a, 14b, 14c of the associated opening switch 12a, 12b, 12c connected. One further leads to the code signal generators 13a, 13b, 13c common to all code signal generators 13a, 13b, 13c power supply line 18 connected to the voltage supply connection 25 of the Evaluation unit 11 is created.

The generators 13a, 13b, 13c are designed so that each one of them characteristic for the assigned opening switch 12a, 12b, 12c Code signal or a characteristic code sequence can generate as soon as the assigned opening switch 12a, 12b, 12c opens or the assigned one Closing switch 17a, 17b, 17c closes. The code signal arrives either via the line section 16a or the line sections 16a, 16b and the closed opening switch 12a or the line sections 16a, 16b, 16c and the closed opening switches 12a, 12b to the test-in connection 23 of the evaluation unit 11, where due to the Content of the individual code signals or code sequences is recognized, which the opening switch 12a, 12b, 12c has addressed.

The operation of the safety switching arrangement described is how follows:

In the normal, trouble-free case, all opening switches 12a, 12b, 12c closed, so that a closed security path 16a, 12a, 16b, 12b, 16c, 12c, 16 is present and in this way via the test-in / test-out connections 23, 24 of the evaluation unit 11 is signaled that on none of the monitoring points assigned to the opening switches 12a, 12b, c12c there is a fault.

As soon as a fault occurs, for example, in the area of the opening switch 12b the opening switch opens on a transfer line or a conveyor belt 12b either automatically or due to manual operation, whereupon the safety path is interrupted and the evaluation unit 11 signals a fault via the test-in / test-out connections 23, 24 becomes.

Since the closing switch 17b was closed at the same time, the code signal generator outputs 13b via the line sections 16a, 16b and the closed opening switch 12a to the test-in input 23 for the opening switch 12b characteristic code signal, on the basis of which the evaluation unit 11 recognizes that of the three opening switches 12a, 12b, 12c the opening switch 12b has been opened. This is the point of failure identified.

The embodiment of Figure 2, in which the same reference numerals corresponding Designating components as in Figure 1 differs from that Embodiment according to Figure 1 in that the code signal generators 13a, 13b, 13c opposite pole of the closing switch 14a, 14b, 14c not to the inputs 14a, 14b, 14c of the opening switches 12a, 12b, 12c, but rather to a common to all closing switches 17a, 17b, 17c Diagnostic line 15 is connected, which to a separate Diagnosis-in connection 26 of the evaluation unit 11 is guided.

This is done by opening an opening switch 12a, 12b, 12c general triggered by the safety path 16a, 12a, 16b, 12b, 16c, 12c, 16 Fault signal via the test-in connection 23 and that for the open Opening switch 12a, 12b, 12c characteristic code signal the special diagnosis-in connection 26 appear. That way the line effort is somewhat larger than in the embodiment according to Figure 1, however, by separating the diagnostic line and safety path the evaluation logic in the evaluation unit 11 is simplified.

According to Figure 3, the code signal generators 13a, 13b, 13c as a core component have a microprocessor 19. The power supply of the microprocessor 19 takes place via a voltage converter 22 which via the voltage supply line 18 to the voltage supply connection 25 of the evaluation unit 11 is created. The voltage converter 22 sets the one present at the output 25 of the evaluation unit Voltage of 24V, for example, into a stabilized 5V voltage. The microprocessor 19 is opened by opening the opening switch 12a, 12b, 12c or closing of the associated closing switch 17a, 17b, 17c activated, whereupon he sends the code signal at his signal output 21 to one Output amplifier 20, from which it to the safety line section 16b arrives. The activation of the microprocessor 19 takes place in that the positive supply voltage line (5 V) an activation line 28 is branched off via the closing switch 17 b to an activation input 27 of the microprocessor 19 leads.

The signal output 21 of the microprocessor 19 is via the amplifier 20 either to the assigned safety line section 16a, 16b, 16c or the diagnostic line 15 (FIG. 2).

Since according to Figures 1 and 3, the safety path when actuating one of the Opening switch 12a, 12b, 12c is open at this point, that is in of the evaluation unit 11 generated monitoring signal in this case interrupted. Thus, it can be in the subsequent transmission of the characteristic code signal over sections of the security path not to a data collision between the monitoring (test) signal and the generator code sequence come.

It is also conceivable that the microprocessor 19 has the characteristic Transmits code signal continuously, the closing switches 17a, 17b, 17c in the path between the signal output 21 and the connection point (14b) of the amplifier 20 would have to be provided. Is preferred in this case the closing switch 17a, 17b, 17c is provided at the output of the amplifier 20.

Inexpensive small microprocessors are available for the application according to the invention, e.g. the PIC 12C508 (8-pin, 8 bit S08 housing) from Microchip available.

LIST OF REFERENCE NUMBERS

11

evaluation

12a

Safety opening switch

12b

Safety opening switch

12c

Safety opening switch

13a

Code signal generator

13b

Code signal generator

13c

Code signal generator

14a

Safety switch input

14b

Safety switch input

14c

Safety switch input

15

diagnostic line

16

Safety path feedback

16a

Security line section

16b

Security line section

16c

Security line section

17a

closing switch

17b

closing switch

17c

closing switch

18

Power Line

19

microprocessor

20

amplifier

21

signal output

22

DC converter

23

Test In connection

24

Test Out Connection

25

Power supply terminal

26

Diagnosis In connection

27

enable input

28

activation line

Claims (10)

1. Safety switching arrangement having at least two break switches (12a, 12b, 12c) which are connected in series to an evaluation unit (11), wherein the evaluation unit (11) initiates a safety signal, when at least one of the break switches (12a, 12b, 12c) opens, and determines which of the break switches (12a, 12b, 12c) has opened,
   characterized in that at least one break switch (12a, 12b, 12c) has an associated code signal generator (13a, 13b, 13c) which, when the associated break switch (12a, 12b, 12c) opens, supplies to the evaluation unit (11) a code signal which is characteristic of the relevant break switch (12a, 12b, 12c) via a line, which leads to the evaluation unit (11) and is common to all the break switches (12a, 12b, 12c) associated with a code signal generator (13a, 13b, 13c), which code signal is analyzed in the evaluation unit (11) and is identified as coming from the relevant break switch (12a, 12b, 12c).
2. Safety switching arrangement in accordance with claim 1, characterized in that each break switch (12a, 12b, 12c) has an associated make switch (17a, 17b, 17c) which is operated jointly with it and activates the associated code signal generator (13a, 13b, 13c) when it closes.
3. Safety switching arrangement in accordance with claim 1 or claim 2, characterized in that the code signal output of each code signal generator (13a, 13b, 13c) is applied to the input (14a, 14b, 14c) of the associated break switch (12a, 12b, 12c) when the latter opens, and the code signal emitted by the relevant code signal generator (13a, 13b, 13c) is passed via the safety line section or sections (16a, 16b, 16c) which leads or lead to the open break switch (12a, 12b, 12c) and via the closed break switch (12b, 12c) located upstream of it to the evaluation unit (11), and is evaluated there.
4. Safety switching arrangement in accordance with claim 1 or claim 2, characterized in that the code signal output of each code signal generator (13a, 13b, 13c) is applied, when the associated break switch (12a, 12b, 12c) opens, to a special diagnosis line (15), which is common to all the break switches (12a, 12b, 12c) and leads to the evaluation unit (11), where the code signal emitted by the activated code signal generator (13a, 13b, 13c) is evaluated.
5. Safety switching arrangement in accordance with claim 1 or claim 2, characterized in that the code signal generator (13a, 13b, 13c) is caused to produce the code signal by the mechanical movement of the break switch (12a, 12b, 12c).
6. Safety switching arrangement in accordance with any one of the preceding claims, characterized in that each code signal generator (13a, 13b, 13c) is connected to the evaluation unit (11) via a voltage supply line (18) which is common to all the code signal generators (13a, 13b, 13c).
7. Safety switching arrangement in accordance with any one of the preceding claims, characterized in that each code signal generator (13a, 13b, 13c) has an ASICS or microprocessor (19) for code signal production.
8. Safety switching arrangement in accordance with claim 7, characterized in that the signal output (21) of the microprocessor (19) is connected via an amplifier (20) to the line (15) leading to the evaluation unit (11), or to the line sections (16a, 16b or 16c, respectively) leading to the evaluation unit (11).
9. Safety switching arrangement in accordance with claim 8, characterized in that the make switches (17a, 17b, 17c) are provided in an activation line (28) which leads to an activation input (27) of the microprocessor ( 19) and branches off from the voltage supply (18, 22), or are provided in the signal output path (20, 21) of the microprocessor (19).
10. Safety switching arrangement in accordance with any one of the preceding claims, characterized in that the evaluation unit (11) has test-in (23), test-out (24), voltage supply (25) and, possibly, diagnosis-in (26) connections.

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