STATUS CHECKING OF FIELD DEVICES OF A BUILDING-ASSOCIATED INSTALLATION FOR TRANSPORTING PEOPLE

Abstract

A method for checking the status of field devices of a building-associated installation for transporting people includes the steps of: sending a command block of a status telegram from a monitoring unit via a series bus to a plurality of field devices; supplementing the status telegram by the field devices that are addressed by the command block; receiving the data block supplemented by the addressed field devices by the monitoring unit; and evaluating the status values in the supplemented data block by the monitoring unit.

Claims

1-15. (canceled)

16. A method for checking a status of field devices of a building-based passenger transport system, the method comprising the steps of: transmitting a command block of a status telegram from a monitoring unit via a serial bus to a plurality of field devices connected to the serial bus; ones of the field devices addressed by the command block supplementing the status telegram wherein each of the addressed field devices receives the command block and determines a status end position in a data block of a status message adjoining the command block, each of the addressed field devices transmitting an associated status value to the monitoring unit via the serial bus when a status end position in the data block is reached, the status value encoding the status of the associated addressed field device; receiving the data block supplemented by the addressed field devices with the monitoring unit; evaluating the status values using the monitoring unit; and controlling operation of the passenger transport system with a central control unit that responds to the evaluated status values.

17. The method according to claim 16 wherein the command block includes an encoded command value that identifies a start of the status telegram.

18. The method according to claim 17 wherein the encoded command value can have different first and second command values, and wherein the first command value indicates that remaining bits of the status telegram and/or the data block thereof are inverted relative to same content remaining bits and/or the data block of the status telegram having the second command value.

19. The method according to claim 16 wherein the command block includes encoded destination addresses that determine which of the field devices are addressed by the status telegram.

20. The method according to claim 16 wherein the command block includes an encoded length value of the status telegram.

21. The method according to claim 16 wherein the data block is divided into status words of a same bit length, the status words being assigned to associated ones of the addressed field devices and in which the status value of the assigned associated field device is coded, and wherein the status end position is a start of the status word assigned to the associated field device.

22. The method according to claim 16 further comprising generating an alarm if the status values received by the monitoring unit indicate a hazard detected by a switch or a security sensor connected to any of the addressed field devices.

23. The method according to claim 16 wherein the status values are encoded with at least one of an error-indicating encoding, and error-correcting encoding and a Hamming encoding.

24. The method according to claim 16 further comprising generating an alarm if the status values received and decoded by the monitoring unit indicate erroneous encoding.

25. The method according to claim 16 wherein all of the field devices connected to the bus are addressed by a plurality of status telegrams regularly transmitted in a cycle, and wherein the field devices are divided into groups, each of the groups being addressed by one of the status telegrams in the cycle.

26. The method according to claim 16 wherein the status telegram is generated regularly, and wherein the monitoring unit determines bits of the data block of the status telegram by a majority formation of bit values of a plurality of the status telegram addressing the associated field devices.

27. The method according to claim 26 wherein the majority formation of bit values of the data block takes place only if at least one status word in the data block that has been coded with error-indicating encoding indicates erroneous encoding.

28. The method according to claim 16 wherein at least two of the status telegram occupy the bus at a predetermined time interval and waiting periods are provided between the status telegrams, and wherein when one of the field devices detects a status change in a connected safety sensor, the one field device starts transmitting a spontaneous telegram to the monitoring unit via the serial bus within the waiting period, the spontaneous telegram including the status change encoded.

29. A communication system for a building-based passenger transport system, the communication system comprising: a plurality of field devices; a monitoring unit; a serial bus connected to the monitoring unit and to the field devices; and wherein the communication system adapted to perform the method according to claim 16.

30. The communication system according to claim 29 wherein each of the field devices includes a synchronization module that comprises a transceiver module and a transmission position determination module, wherein the transceiver module transmits and receives bit sequences via the serial bus and is adapted to recognize the command block of the status telegram and to transmit status values within the status telegram, and wherein the transmission position determination module is adapted to determine the status end position from the command block of the status telegram received with the transceiver module and to thus trigger the transceiver module to transmit the status value.

Description

DESCRIPTION OF THE DRAWINGS

[0048] FIG. 1 schematically shows a building-based passenger transport system in the form of an elevator system according to an embodiment of the invention.

[0049] FIG. 2 schematically shows a field device for a building-based passenger transport system according to an embodiment of the invention.

[0050] FIG. 3 shows a flow chart for a method for checking the status of field devices of a building-based passenger transport system according to an embodiment of the invention.

[0051] FIG. 4 is a diagram of a status telegram for the method from FIG. 3.

[0052] FIG. 5 is a diagram of a telegram cycle for the method from FIG. 3.

[0053] The drawings are merely schematic and not to scale. In the different figures, identical reference signs denote identical or similar features.

DETAILED DESCRIPTION

[0054] FIG. 1 shows a building-based passenger transport system 10 in the form of an elevator system 10. An elevator system will be described below by way of example. However, it should be understood that other passenger conveyors 10, such as escalators or moving walkways, may comprise such communication systems, monitoring units, field devices, and sensors as described below.

[0055] The elevator system 10 comprises an elevator shaft 12, in which an elevator car 14 and a counterweight 16 can be moved. For this purpose, the elevator car 14 and the counterweight 16 are suspended on a cable-like or belt-like suspension means 18, which can be moved by a drive motor 20. The operation of the elevator system 10 and in particular the drive motor 20 can be controlled using a central control unit 22.

[0056] In order to be able to ensure correct functioning and in particular safety of the elevator system 10, a plurality of field devices 26 are accommodated in a structure 24 that accommodates the elevator system 10. In this case, the field devices 26 are distributed over the structure 24. The field devices 26 may, for example, comprise a door switch 28 or be connected to a door switch 28, which can monitor a closure state of doors 30, in particular of doors on a floor, of the elevator system 10. The door switches 28 may be considered to be safety sensors. Furthermore, a ladder 32 may be mounted close to a floor or a pit of the elevator shaft 12, for example, the correct, neat positioning of which ladder on a side wall of the elevator shaft 12 is monitored, for example, by means of a switch 33 connected to a field device 26. The switch 33 may also be considered to be a safety sensor. The field devices 26 may be part of a communication system 34 of the elevator system 10 and may be connected to the central control unit 22 or in particular to a monitoring unit 38 integrated there for example, by means of a serial bus 36, for example. The field devices 26 are arranged in series one behind the other, with two field devices 26 arranged one behind the other being connected to the serial bus 36 in each case.

[0057] FIG. 2 shows a field device 26. The field device 26 is set up to output sensor signals generated by one or more sensors 28 and/or to receive control signals to be implemented by one or more actuators. In this case, the field device 26 itself may for example comprise one or more sensors 28 and/or one or more actuators. The field device 26 may output the sensor signals generated by the sensor to other field devices 26, in particular to the central control unit 22 or the monitoring unit 38, via the serial bus 36, or may convey control signals received from other devices, in particular the central control unit 22, to an actuator via said bus 36, such that said actuator can implement the control commands contained therein. Alternatively or additionally, a field device 26 may function as a node that can, for example, receive sensor signals from an external sensor and/or from another field device 26 and then output said signals to further devices, or that can receive control signals from further devices and then forward said signals to an external actuator, such that said actuator implements the control signals.

[0058] FIG. 2 shows that the field device 26 may comprise a synchronization module 40, which in turn may be divided into a transceiver module 42, a transmission position determination module 44 and a collision detection module 46. The functions of the modules 42, 44, 46 will be described in greater detail with reference to the following figure, FIG. 3. For example, the synchronization module 40 may be implemented as a CPLD (complex programmable logic device) to implement the functions at high speed.

[0059] The field device may further comprise a microcontroller 48, which may include its own transceiver module 50 and a CPU 52 (central processing unit). The transceiver module 50 and/or the transceiver module 42 may be configured as a UART (universal asynchronous receiver transmitter).

[0060] Furthermore, FIG. 2 shows that the serial bus 36 can be connected to earth (0 V) by the transceiver module 42 by means of a transistor 51, in order to transmit the bit 0 on the bus 36. If the bus 36 is not earthed by any of the bus participants, then the bit 1 is transmitted. Furthermore, the transceiver module 42 is supplied with the current value of the bus in the form of a signal derived from a comparator 53, which compares the voltage on the bus 36 with a reference signal Vref.

[0061] It should be noted that transmitting on the serial bus 36 means that the relevant bus participant (such as the monitoring unit 38 or a field device 26) places bits 0 and 1 on the bus 36, as just described. Conversely, receiving means that the relevant bus participant evaluates these bits using the comparator.

[0062] The monitoring unit 38 may be analogously connected to the serial bus 36 and/or may also have a transceiver module 50 (for example, a UART).

[0063] FIG. 3 shows a flow chart for a method for checking the status of the field devices 26 of the building-based passenger transport system 10, which can be carried out by the communication system 34 and in particular the monitoring unit 38 and the field devices 26.

[0064] In step S10, the monitoring unit 38 determines the safety-relevant field devices 26 connected to the bus 36. The field devices and their bus addresses can for example be stored in a table of bus nodes in the monitoring unit 38. It is also possible for field devices 26 to register on the bus 36 or with the monitoring unit 38 via the bus 36.

[0065] Furthermore, the monitoring unit 38 forms groups of field devices 26, which are intended to be addressed simultaneously with a status telegram 54, as shown for example in FIG. 4. In the following steps S12 to S16, a status telegram 54 is then generated and evaluated for each of the groups in one cycle.

[0066] In step S12, the monitoring unit 38 transmits, via the serial bus 36, a command block 56 of the status telegram 54 to the field devices 26 connected to the serial bus 36, which relates to a group of field devices 26 corresponding to the cycle.

[0067] In general, the status telegram 54 shown in FIG. 4 is divided into a command block 56 and a data block 66. In turn, the command block 56 is again divided into a command value 58, a length value 60 and two address values 62, 64 in this order. Other telegrams that are transmitted via the bus 36 may also have this structure. In contrast to the status telegram 54, these telegrams may also have a checksum.

[0068] The start of the command block 56 encodes a command value 58 which identifies the start of a status telegram 54. For example, the command value 58 may be 4 bits long.

[0069] It is possible for a status telegram 54 to be identified by two different command values 58, such as the binary numbers 0011 and 1100. The different command values may indicate that the remaining bits of status telegram 54 for the second command value 58 (such as 1100) and/or its data block 66 are inverted relative to the bits of a corresponding status telegram 54 with the first command value 58 (such as 0011) or its data block 66 having the same content. For example, the monitoring unit 38 can alternately transmit status telegrams with the first command value 58 and the second command value 58.

[0070] After the command value 58, the status telegram 54 can encode a length value 60 or a telegram length 60. This length value can, for example, represent the next 4 bits of the status telegram 54 and/or indicate how long the status telegram 54 is (in bytes).

[0071] The remainder of the command block 56 may be formed by two address values 62, 64. The address values may each have the length of one byte, i.e. 8 bits. For example, the address values 62, 64 encode a source address of the telegram and a destination address, as may be the case with all telegrams. For a status telegram 54, the address values 62, 64 can also encode the groups of field devices 26 which are to be addressed by the status telegram 54.

[0072] By way of example, the address value 62 may specify a first addressed field device 26 and the address value 64 may specify a last addressed field device 26 of an address interval. However, it is also possible for the destination address 64 to specify the first addressed field device 26. From the length value 60, the number of field devices 26 addressed by this status telegram 54 is then obtained. With a maximum length of the status telegram of 15 bytes, the data block 66 can contain a maximum of 12 data bytes.

[0073] In step S14, all the field devices 26 receive the command block 56 of the status telegram 54 and evaluate said block with the synchronization module 40. In particular, the command block 56 is received and decoded by the transceiver module 42. When a command value 58 for a status telegram 54 has been received, the elements 60, 62, 64 are forwarded to the transmission position determination module 44. Telegrams having other content are forwarded by the transceiver module 42 to the transceiver module 50.

[0074] When the transmission position determination module 44 of a field device 26 determines that the field device is addressed by the status telegram 54, it determines a status end position in the data block 66. The data block 66 may be divided into status words 68 of the same bit length (such as 8 bits, i.e. one byte), which are assigned to the addressed field devices 26. A status word may additionally contain start and stop bits. The status end position may then be determined, for example, by subtracting the address of the field device 26, which may be stored in the synchronization module 40, from the first destination address (which may be stored in the address value 64). If the result is greater than 0 and less than the length of the data block 66, the result is the status end position.

[0075] The transmission position determination module 44 then waits until the transmission position has been reached in the telegram. The time difference to the end of the command block 56 may be determined by multiplying the time unit for a bit by the bit length of a status word 68 and by the transmission position.

[0076] When the transmission position has been reached, the transmission position determination module 44 instructs the transceiver module 42 to transmit a status value of the field device 26 to the monitoring unit 38 via the serial bus 36.

[0077] The status value may encode the status of the field device 26 itself or the status of one or more of the safety sensors 28 that are connected to the corresponding field device 26. The status value may be stored in the synchronization module 40 and/or may be updated by the microcontroller 48 on a regular basis.

[0078] For each status word 68, an extended (8,4) Hamming code may be used. In this case, 4 data bits can be mapped via the 7,4 Hamming code generator matrix to 7-bit code words and extended by an additional parity bit in order to achieve a minimum Hamming distance of 4 (see, for example, https://en.wikipedia.org/wiki/Hamming7,4).

[0079] Subsequently, an XOR operation of the status value with the address of the field device 26 which transmits the status value can take place. Therefore, the monitoring unit 38 can check whether the status value comes from the expected field device 26 in which the expected address is applied to the status value by means of an XOR operation and a valid Hamming code results.

[0080] The encoding of the status value which is transmitted in the status word 68 can be carried out by the synchronization module 40 or by the microcontroller 48.

[0081] In step S16, the monitoring unit 38 receives the data block 66 supplemented by the addressed field devices 26 and evaluates the status values.

[0082] If the status telegrams 54 are generated regularly for a group of field devices, the monitoring unit 38 can determine the bits of the data block 66 of a status telegram 54 by means of a majority formation of bit values of a plurality of status telegrams 54 addressing the same field devices 26.

[0083] For example, the data blocks 66 of successive status telegrams 54 which relate to the same group of field devices 26 can be combined by means of majority formation.

[0084] It may also be the case that the majority formation takes place in a field-device-specific manner, i.e. the last received status words assigned to a field device 26 are combined in this way.

[0085] The majority formation of bits of the data block 66 and/or of a status word 68 can only take place if at least one status word 68 that has been encoded with error-indicating encoding indicates erroneous encoding.

[0086] For example, the consideration time window may be three cycles long. The validity of the information can be evaluated per status word 68, i.e. per field device 26. First, the error correction of the 8,4 Hamming code may be applied to each of the last-received status words 68. The most recent valid status word 68 can then be trusted. If none of the considered status words 68 from a field device 26 is valid, a substitute status word is formed over bitwise majority of the last three status words 68. If this is also invalid, an erroneous state of the field device 26 or the communication connection can be assumed.

[0087] In the case of a correct 8,4 Hamming code, the status value is determined and it is checked whether the corresponding field device 26 signals a safety-relevant issue.

[0088] In both cases, i.e. when the status values received by the monitoring unit 38 indicate a hazard detected by the safety sensors 28 connected to the field devices 26 or when the status values received and decoded by the monitoring unit 38 indicate erroneous encoding, the monitoring unit 38 generates an alarm. The alarm can be relayed to the central controller 22, which then stops the operation of the system 10, for example.

[0089] After step S16, the monitoring unit 38 may transmit the next status telegram 54 of a cycle. It should be noted that the steps S12 and S16 can also be carried out using corresponding hardware at least partially in parallel.

[0090] FIG. 5 shows a diagram for a query cycle 70, by means of which all the field devices 26 connected to the bus 36 can be queried once by means of a plurality of status telegrams 54. The field devices 26 are divided into groups which are each addressed by a status telegram 54 from the cycle 70. The query cycles 70 can be transmitted regularly.

[0091] A query cycle 70 is shown by means of which approximately 200 field devices 26 can be addressed in a cycle time of about 180 ms. In order to be able to address the 200 field devices 26, 17 status telegrams are transmitted in the query cycle 70, which can address 12 field devices 26 in each case.

[0092] Each of the status telegrams 54 may have a length of approximately 9 ms. A waiting period 72 is provided between the status telegrams 54, which may be approximately 1.5 ms. The waiting periods may be used by the field devices 26 or other bus participants to transmit their own telegrams. In FIG. 5, a spontaneous telegram 74 is shown by way of example for this purpose.

[0093] The monitoring unit can only wait for spontaneous telegrams 74 between the status telegrams. At the end of a query cycle 70, a longer waiting period 74 for normally prioritized telegrams may be provided.

[0094] In step S18 (see FIG. 3), a field device 26, when it detects a status change in a connected safety sensor 28, can start transmitting a spontaneous telegram 74 to the monitoring unit 38 within a waiting period 72, which encodes the status change.

[0095] A spontaneous telegram 74 can then be immediately decoded by the monitoring unit 38. If a spontaneous telegram 74 is transmitted, the monitoring unit 38 can interrupt the query cycle 70 being carried out.

[0096] It is possible for the monitoring unit 38 to confirm the receipt of the spontaneous telegram 74 with a further telegram to the transmitter of the spontaneous telegram 74. Even erroneous reception can be communicated by a corresponding telegram to the transmitter of the spontaneous telegram 74. If the transmitter of the spontaneous telegram 74 does not receive a confirmation telegram or a telegram about erroneous reception, the transmitter can repeat the transmission of the spontaneous telegram 74 in the next waiting period 72.

[0097] For example, to prevent two field devices 26 from simultaneously transmitting a spontaneous telegram 74, the collision detection module 46 of each field device 26 monitors the bus 36. For this purpose, the collision detection module 46 can monitor the bus at a sample rate which is substantially greater than the frequency of the bit values. For example, this sample rate may be greater than the bit frequency by at least a factor of 10.

[0098] If the collision detection module 46 detects that the bus 36 is already occupied before the start of an intended transmission, it can suppress the transmission. In this case, collisions can be completely avoided.

[0099] If transmission has already started, a collision can be detected by the field device 26, which sets the bus signal to 1 but instead detects 0 on the receiving side, i.e. after the comparator 53. In this case, the field device 26 that has detected the collision aborts its transmission and the bit of the other field device 26 is transmitted correctly.

[0100] Finally, it should be noted that terms such as comprising, including, etc. do not preclude other elements or steps, and terms such as a or an do not preclude a plurality. It must further be noted that features or steps which have been described with reference to one of the above embodiments can also be used in combination with other features or steps of other embodiments described above.

[0101] In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.