METHOD FOR TRANSFERRING DATA BETWEEN A CENTRAL CONTROL UNIT AND A MULTIPLE OF DECENTRALIZED DEVICES AND CORRESPONDING DEVICES

Description

[0001] The invention relates to a method for transmitting data between a central control device and a plurality of decentralized devices, as well as corresponding devices, wherein in particular a broadcast or multicast transmission of data is provided.

[0002] In modern, automated warehouse and logistics systems, the demand for automated guided vehicles (AGVs) has been growing for years. These AGVs are typically based on floor-based conveyor systems with automatically controlled vehicles whose primary task is material transport. They essentially consist of one or more automated guided vehicles (AGVs) with integrated control intelligence, a master controller, location determination devices, and a communication device for exchanging order data between the master controller and the AGV. Standardized radio systems such as Wi-Fi or Bluetooth are frequently used as the communication medium.

[0003] The goal of the major providers and operators of such logistics systems is to have logistics halls that are empty of people. The AGVs receive their driving orders from a master control system and carry out their work completely autonomously. When their batteries are empty, they automatically drive to a charging station to be recharged. In principle, absolutely no human intervention is necessary, although this is of course a purely theoretical consideration. It does happen again and again that vehicles break down due to technical defects or require maintenance. Even a load that has slipped on an AGV, for example, can make human intervention necessary. For reasons of functional safety, the vehicles must be brought to a safety stop or travel at a safely reduced speed as soon as a person enters the system.

[0004] Some manufacturers only partially implement this requirement in a safety-oriented manner. Other manufacturers rely on existing safety protocols such as PROFIsafe. This approach is the right one from a functional safety perspective. The PROFIsafe system has been proven successful for many years and can also be transmitted cost-effectively via radio.

[0005] Due to cyclical, bidirectional point-to-point communication between the safety controller, referred to as F-Host in PROFIsafe, and the safety-related field devices, referred to as F-Devices in PROFIsafe—that is, between the safe master controller and the AGVs—a high volume of communication occurs. This volume grows linearly with the number of AGVs in operation.

[0006] In addition, the order data must also be transmitted over this transmission channel. Due to the available bandwidth in Bluetooth or WLAN systems, the number of vehicles is severely limited. This type of solution is therefore not practical for medium to large systems. Due to the addressing and security measures used, PROFIsafe is not suitable for broadcast or multicast transmission.

[0007] US 2007 / 0115865 A1 describes a method comprising receiving a multicast diagnostic request at a node, point or terminal in a wireless local area network, wherein the multicast diagnostic request defines a report timeout indicating a time interval in which a multicast frame should be received at the node, point or terminal or otherwise a trigger condition is met, and the method comprises transmitting a multicast diagnostic report to another node, point or terminal in the wireless local area network if the trigger condition is met.

[0008] EP 2 115 948 A1 discloses a method for the optimized transmission of data between a control device and a plurality of field devices connected to one another via an IP-based communications network, wherein the data transmission is controlled using a Profinet protocol. In this method, the data to be transmitted from a control device to a plurality of field devices can be transmitted in a single frame divided into data fields, and the data to be transmitted from a plurality of field devices to a control device can also be transmitted in a single common frame divided into data fields, in order to increase the transmission rate compared to the transmission rate achieved with standard Profinet frames by reducing the number of filler bits to be transmitted.

[0009] In EP 1 509 005 A1, it is proposed to define a broadcast telegram within the point-to-point transmission protocol for the transmission of data via a bus network to which several participants are connected and in which data is transmitted from at least one participant to at least one further participant per communication cycle by means of a data transmission protocol designed for point-to-point transmission, within which broadcast telegram selected data can be transmitted in a broadcast transmission mode.

[0010] However, these methods are also not suitable for enabling safety-oriented communication between the control system and the AGVs in the driverless transport systems described above, which can be used effectively in medium to large systems.

[0011] The invention is therefore based on the object of providing a method and a control and data transmission system with which a simplified or improved, in particular more efficient, data transmission between a control device and decentralized devices can be achieved.

[0012] This object is achieved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims, wherein the stated features and advantages can essentially apply to all independent claims.

[0013] A core idea of ​​the invention is a unidirectional transmission of a multicast or broadcast telegram from a central control device to a plurality of decentralized devices, wherein the data telegram comprises, in particular, secure user data and additional information to secure the transmission, and wherein, to protect against a systematic delay in the transmission of the data telegram on the transmission path, which cannot usually be detected in a unidirectional transmission, it is provided to monitor the transmission time of the data telegram and to trigger a predetermined security reaction if a predetermined transmission time is exceeded, wherein the invention provides, in particular, two variants for monitoring the transmission time, which can be used alternatively or cumulatively. The first variant provides for time synchronization between the transmitting and receiving unit, i.e.between the central control device and the respective decentralized device, while the second variant provides for monitoring the quality of a separately running bidirectional data transmission by means of a transmitter and / or receiver-side diagnostic unit, which uses the same transmission path as the unidirectional transmission of the data telegram.

[0014] A method for transmitting data between a central control device and at least one decentralized device comprises the steps according to claim 1.

[0015] The unidirectional transmission of the data telegram typically occurs to a plurality of decentralized devices, with the data telegram being generated and transmitted as a multicast data telegram addressed to a predefined group of decentralized devices. Generating and transmitting the data telegram as a broadcast data telegram addressed to all decentralized devices is another example of unidirectional transmission of a data telegram.

[0016] In the case of a multicast data telegram, the data telegram includes a multicast address that addresses the group of decentralized devices to which the data telegram is addressed. In this case, each of the decentralized devices belonging to the group knows the corresponding multicast address.

[0017] A group of decentralized devices is selected or addressed by specifying a spatial area. For this purpose, the data telegram is configured for multicast transmission of data to a group of devices located within a defined spatial area. For this purpose, the data telegram includes identification information that identifies the defined spatial area. The at least one decentralized device is configured to detect whether it is currently located within the area identified by the identification information.

[0018] Detecting whether the respective decentralized device is located within the identified spatial area can be achieved in various ways. For example, the decentralized device can have a position-determining device, such as a GPS receiver, as well as means for determining whether a position currently determined by the position-determining device is within the identified spatial area. However, a variety of other sensors are also conceivable that can be suitable for determining whether the decentralized device is located within the identified spatial area. In identifiable spatial areas, for example, corresponding devices for transmitting signals detectable by the respective sensor can be arranged.

[0019] The transmission of a broadcast or multicast data telegram can also be repeated, in particular cyclically in predetermined transmission cycles.

[0020] In a first variant of the invention, the control device and the at least one decentralized device each have a timer. With the typically provided plurality of decentralized devices, each of the decentralized devices has a timer. Furthermore, it is provided that the timer in the control device is synchronized with the respective timer in the at least one decentralized device. The synchronization takes place in particular before commissioning of the respective at least one decentralized device, and alternatively or additionally at predetermined cyclical time intervals. The time intervals of a cyclical synchronization can advantageously be determined depending on the running error of the timers used.

[0021] In this variant, the control device generates a timestamp when generating the data telegram, which is transmitted within the data telegram. Monitoring the transmission duration is based on the timestamp. To generate the timestamp, the control device retrieves the current time from the timer.

[0022] By synchronizing the respective decentralized device before commissioning, it can be ensured that the timers used to monitor the transmission duration are already synchronized when a data telegram is first transmitted after commissioning.

[0023] The timer in the control device can advantageously serve as a reference timer during synchronization, with which the timers of the decentralized devices are synchronized. It is also conceivable for a reference timer to be arranged in a separate reference module, and for both the timer in the control device and the timers in the decentralized devices to be synchronized with this reference timer.

[0024] The reference timer can in turn be advantageously synchronized with a time standard at predetermined time intervals, for example with the help of the DCF77 time signal transmitter.

[0025] In a second variant of the invention, the method comprises the following steps: Establishing a data connection designed for bidirectional communication between the control device and the at least one decentralized device, wherein the data telegram is transmitted unidirectionally from the control device to the at least one decentralized device via this data connection, and monitoring the transmission quality of the data connection by the control device and / or by the at least one decentralized device, wherein the monitoring of the transmission duration of the data telegram is carried out as a function of the monitored transmission quality.

[0026] In an advantageous embodiment of the invention, the at least one decentralized device is designed as a driverless transport vehicle (FTF).

[0027] In this embodiment, in the second variant of the invention described above, order data are typically transmitted from the control device to individual decentralized devices via a bidirectional data connection, which are used by the respective decentralized device to process individual transport orders.

[0028] Bidirectional data transmission can be carried out via a wireless network, for example using WLAN or Bluetooth.

[0029] The control device can, for example, use a corresponding diagnostic unit to monitor the transmission quality of the bidirectional data connection and, in particular, determine a delay time with which the control device receives a response to a data message from the decentralized device. From this delay time, the control device can derive how long the transmission of the data message from the control device to the decentralized device took or how long it took at most. Alternatively or additionally, analog monitoring can be carried out using a corresponding diagnostic unit arranged in the decentralized device, whereby the decentralized device can, in particular, determine a delay time with which the decentralized device receives a response to a data message from the control device.

[0030] If the unidirectional transmission of the broadcast or multicast data telegram is carried out as a unidirectional transmission using the same data connection that is used for the bidirectional communication, the respective diagnostic unit can also estimate a transmission time for this transmission or determine a value that indicates the maximum required transmission time.

[0031] In this way, the respective diagnostic unit can monitor the transmission time of the data telegram from the central control device to the at least one decentralized device and, if the transmission time exceeds a predetermined value, trigger a predetermined safety reaction. In the case of a diagnostic unit arranged in the control device, the safety reaction can, for example, consist in shutting down the relevant decentralized device or all of the decentralized devices, with a corresponding shutdown command being transmitted from the control device to the relevant decentralized device(s) for this purpose. In the case of a diagnostic unit arranged in the decentralized device, the safety reaction can also advantageously consist of shutting down the relevant decentralized device, with the shutdown being initiated by the diagnostic unit arranged in the decentralized device.It is therefore particularly advantageous for a decentralised device to be switched off or shut down or otherwise brought into a safe state if the diagnostic unit of the decentralised device in question determines that communication is taking too long or if the decentralised device receives a corresponding switch-off command from the control device.

[0032] For wireless unidirectional transmission of the broadcast or multicast data telegram, the control device advantageously comprises a transmitting unit, and the decentralized devices comprise corresponding receiving units. However, the transmission of the broadcast or multicast data telegram does not necessarily have to be wireless. Rather, wired data transmission can also be provided.

[0033] Furthermore, various known or standardized transmission protocols can be used to transmit the broadcast or multicast data telegram. Known protocols can also be appropriately supplemented, or new protocols can be provided to implement the data transmission.

[0034] The multicast or broadcast data telegram is used primarily for the transmission of safety-relevant or safety-oriented data. For example, in decentralized devices designed as AGVs, the safety-oriented data can be used to safely shut down the decentralized devices or to instruct them to travel at a safe, reduced speed. The transmission of the safety-oriented data in the form of the multicast or broadcast data telegram can occur, for example, in response to a sensor signal received by the control device, which indicates, for example, that a person has entered the system. A corresponding sensor could be designed as a light curtain or a safety gate.

[0035] However, any other suitable type of safety-oriented or safety-relevant data is also conceivable, such as those used in the area of ​​functional safety of technical systems or automation systems.

[0036] For the transmission of the multicast or broadcast data telegram, it is particularly advantageous to use a secure communication protocol that employs known methods for error prevention and detection. In particular, protocols are used that handle various error types, such as corruption, loss, or transposition. For example, a sequential number, a sender ID, and a CRC checksum can be provided.

[0037] In order to also manage the error type of delay during the unidirectional transmission of the multicast or broadcast data telegram, which usually requires bidirectional communication, the invention provides for monitoring the transmission duration of the multicast or broadcast data telegram.

[0038] A control device for controlling a plurality of decentralized devices, which is suitable for carrying out the method described above, comprises a means for generating a data telegram for multicast transmission of data to a group of devices, a means for unidirectional transmission of the data telegram to at least one decentralized device, and a means for monitoring the transmission duration of the unidirectional transmission of the data telegram from the central control device to the at least one decentralized device.

[0039] In a first advantageous embodiment of the control device, the means for monitoring the transmission duration comprises a timer and means for synchronizing the timer with a timer arranged in the at least one decentralized device, wherein the means for generating the data telegram is designed to generate a time stamp and to transmit this within the data telegram.

[0040] In a second advantageous embodiment of the control device, it is designed to establish a data connection designed for bidirectional communication with the at least one decentralized device, wherein the means for unidirectionally transmitting the data telegram is designed to unidirectionally transmit the data telegram via the data connection, and the means for monitoring the transmission time comprises a diagnostic unit which is designed to monitor the transmission quality of the data connection designed for bidirectional communication, to monitor the transmission time of the unidirectional transmission of the data telegram as a function of the monitored transmission quality, and to trigger a predetermined safety reaction if the transmission time exceeds a predetermined value.

[0041] The above-mentioned technical problem is further solved by a device which can be controlled by a central control device and which is designed to receive a data telegram for the multicast transmission of data from the control device, wherein the data telegram comprises a time stamp, and which comprises a timer and means for synchronizing the timer with a timer arranged in the control device, as well as a means for monitoring the transmission duration of the data telegram from the central control device to the device as a function of the time stamp contained in the data telegram and using the timer, and a means for triggering a predetermined safety reaction if the transmission duration exceeds a predetermined value.

[0042] The invention also includes a control and data transmission system which comprises a control device as described above and at least one device as described above which can be controlled by the control device, as well as a communication network via which the control device can transmit data to the at least one device.

[0043] It should be noted that the control device, the device controllable by the control device, and the control and data transmission system can each advantageously be designed to carry out the different embodiments of the method described above.

[0044] These and other features and advantages of the present invention will become apparent from the embodiments described below with reference to the accompanying drawings. Fig. 1 is a schematic representation of a decentralized device designed as a driverless transport vehicle, Fig. 2 is a schematic representation of a temporal synchronization in a first preferred embodiment of a control and data transmission system according to the invention, Fig. 3 is a schematic representation of an operating phase of the Fig. 2 shown control and data transmission system, and Fig. 4 a schematic representation of a second preferred embodiment of a control and data transmission system according to the invention.

[0045] The invention enables unidirectional, particularly cyclic, transmission of secure output data from a central point or a central controller to more than one decentralized device, such as an automated guided vehicle (AGV), in the form of a multicast or broadcast data telegram. The transmission is particularly wireless, for example, via a radio link or by means of optical transmission. The exemplary embodiments presented below relate to the control of AGVs and assume wireless transmission of the multicast or broadcast data telegrams. However, the invention can also be used in wired applications to save bandwidth there as well.

[0046] Fig. 1 shows a schematic representation of a decentralized device 100 configured as an automated guided vehicle (AGV). The AGV 100 comprises a receiving unit 110 for evaluating data telegrams received via a receiving interface 120, wherein the receiving interface 120 is configured, for example, to receive radio signals. In the example shown, the AGV 100 is configured to control the safe outputs 132 and 134 depending on safe output data received by the receiving unit 110. For example, the safe outputs 132 and 134 serve to control the drive of the AGV 100.

[0047] The Figuren 2 and 3show a schematic representation of a first preferred embodiment of a control and data transmission system 10 according to the invention, which comprises a central control device 200 and a plurality of decentralized devices designed as AGVs, of which only devices 101 and 102 are shown as examples for the sake of simplicity. It should be noted that the invention can be used particularly advantageously in a system with a plurality of decentralized devices.

[0048] The control device 200 comprises a transmitting unit 210, which transmits a multicast or broadcast data telegram via a transmitting interface 220. In the illustrated embodiment, this data telegram contains the secure user data for the secure outputs 132 and 134 of the respective devices 101 and 102, as well as additional information to secure the transmission. To secure communication, existing mechanisms, for example, from PROFIsafe or Interbus Safety, can advantageously be used. For the errors to be detected, a sequential number, a sender identifier, and a CRC checksum can be provided in the data telegram. These measures can be used to detect a swap or alteration of telegrams. The sequential number can be used to trigger a watchdog in the respective receiver 101 or 102. These measures are comparable to existing safety protocols.As an alternative to sender identification, standard network mechanisms such as subnets can be used.

[0049] However, since the transmission of the multicast or broadcast data telegram is a unidirectional communication, components that cause a systematic delay on the transmission path, also known as components with storing behavior, cannot be detected.

[0050] For this reason, PROFIsafe, for example, uses bidirectional communication to detect such errors, with the disadvantages already described above, especially when used in the logistics sector.

[0051] In order to be able to detect such errors even in unidirectional communication, the invention provides timers 140 and 240, respectively, in the AGVs 101 and 102 as well as in the control device 200, wherein time synchronization takes place between the transmitting station 200 and the receiving units 101 and 102 before the start of the individual AGVs. For this purpose, there are already proven standards for use in the Ethernet environment, e.g., the IEEE 1588 standard or the Network Time Protocol (NTP), which can be used when using Ethernet-based communication or adapted accordingly for use with other transmission protocols.

[0052] As soon as a receiving unit 101 or 102 has the current time and receives valid safety protocols, it can validate the payload data and output it at outputs 132 and 134. For this purpose, the transmitting unit 210 adds a timestamp to each multicast or broadcast data telegram to be transmitted using the timer 240, and the respective receiving unit 110 monitors the transmission duration of the unidirectionally transmitted data telegram based on the timestamp and using the synchronized timer 140. If a predefined limit value stored in the respective decentralized device is exceeded, the receiving unit 110 triggers a predefined safety reaction, which may, for example, consist of shutting down the drive.

[0053] In the illustrated embodiment, time synchronization does not occur exclusively when the system is switched on. It also occurs at appropriate intervals, both to keep the times in the receiving units 101 and 102 up to date and to reintegrate receiving units that were switched on later or had failed into the running system.

[0054] Before a receiving unit 110 may switch on the safe outputs, a successful time synchronization between the transmitting unit 210 and the respective receiving unit 110 is necessary. This time synchronization, which in the illustrated embodiment takes place upon switching on and at suitable time intervals during operation, is Fig. 2 symbolically represented by arrows 301 and 302.

[0055] If the receiving unit 110 evaluates the time synchronization as positively completed, the Fig. 3 illustrated operating phase, in which the transmitting unit 210 sends broadcast data telegrams to all participants or multicast data telegrams to participant groups, which contain the safety-related output data, in the illustrated embodiment, for example, the release for the drives of the respective AGV 101 or 102. The transmission of the multicast or broadcast data telegrams is in Fig. 3 symbolically represented by arrows 401 and 402.

[0056] It should also be noted that the described components of a decentralized device do not necessarily have to be integrated into the decentralized device, but can also form components of a separate remote module, wherein in particular only the functionality of monitoring the transmission duration and / or triggering a safety reaction can be outsourced to a separate module in order to expand existing devices with a functionality according to the invention.

[0057] In Fig. 4 is a schematic representation of a second preferred embodiment of a control and data transmission system 20 according to the invention. For the sake of simplicity, Fig. 4 only one decentralized device 100' is shown, although it should be noted that in this embodiment, a plurality of decentralized devices are also advantageously provided.

[0058] This design provides for monitoring the quality of data transmission using a diagnostic unit. Since the AGVs require a bidirectional data connection to process orders, this can be used to monitor the connection quality. The prerequisite for this is that the safety-relevant data is exchanged over the same connection, albeit unidirectionally, but using the same data connection. This eliminates the need to transmit the timestamp, as this diagnostic unit provides the information to the safe logic system that leads to the AGV shutdown when the maximum permissible delay time is exceeded.

[0059] In the Fig. 4 In the illustrated embodiment, a control device 200' is provided, which comprises a higher-level PLC 250 and a safe PLC 270, which can communicate with each other. The decentralized device 100', designed as an AGV, comprises a local PLC 150 with a plurality of I / O devices connected to it, wherein said device comprises standard I / O devices 171, 172, 173, and 174, as well as safe or safety-related I / O devices 181 and 182. The I / O devices can be connected to the local PLC 150, for example, via a bus, for example a backplane bus. The job data of the AGV 100' is transmitted from the higher-level PLC 250 to the local PLC 150 by means of bidirectional communication.

[0060] This communication is represented by arrow 510. In the illustrated embodiment, communication 510 is implemented as wireless communication.

[0061] In the illustrated embodiment, the multicast or broadcast data telegram is transmitted unidirectionally from the safe PLC 270 from the control device 200' to the AGV 100', using the same communication connection as for the bidirectional transmission of the order data. In other words, the multicast or broadcast data telegram is sent to the higher-level PLC 250 and from there to the local PLC 150 and evaluated. If valid, the safety-related data contained in the multicast or broadcast data telegram is output to the safe I / O devices 181 and 182, respectively, which in the illustrated embodiment are designed as safe outputs. The unidirectional transmission of the safe output data to the safe outputs 181 and 182 is in Fig. 4 represented by the arrow 400.

[0062] The transmission quality of the bidirectional data transmission 510 can be determined by means of a diagnostic unit 260 arranged in the safe PLC 270, wherein the diagnostic unit 260 initiates the transmission of a shutdown command to the AGV 100' if the monitoring of the bidirectional data transmission 510, which is used to transmit the order data, shows that a predetermined delay time is exceeded.

[0063] Alternatively or additionally, a diagnostic unit 160 can also be arranged in the AGV 100', which monitors the transmission quality of the bidirectional data transmission 510 and switches off the drive of the AGV 100' if a predetermined delay time is exceeded.

[0064] It is also conceivable that a bidirectional data transmission takes place between the diagnostic units 260 and 160 for test purposes at cyclic intervals, which Fig. 4is shown as arrow 520, and the transmission quality of this bidirectional data transmission 520 is monitored.

[0065] The use of the invention is not limited to FTFs, but can be used independently of the infrastructure in any application in which broadcast or multicast messages are to be sent to many participants with a defined time expectation.

[0066] The method according to the invention also allows, for example, group switching via the cloud for energy supply networks.

[0067] The invention offers a variety of advantages, a particular advantage being that a large number of receivers can receive security-related data without overloading the respective network with the otherwise necessary point-to-point communication. This saves bandwidth and ensures reliable broadcast or multicast transmission.

[0068] In addition, the invention can be used in various application fields from safety to energy supply, offers a cost-effective solution and enables fast response times, as all participants can be addressed simultaneously.

[0069] Certain applications, for example the simultaneous safe control of a large number of AGVs in the logistics industry, are only made possible by the method according to the invention.

[0070] Simultaneous switching of operating modes is also possible, for example, reducing speed when a person enters the danger zone. This opens up further possibilities for human-machine interaction.

Claims

1. A method for transmitting data between a central control apparatus (200, 200') and at least one decentralized device (101, 102, 100'), having the following steps: - generating, in the central control apparatus (200, 200'), a data telegram for the multicast transmission of data to a group of devices that are located in a defined spatial region, the data telegram comprising identification information that identifies the defined spatial region, - unidirectionally transmitting the data telegram from the central control apparatus (200, 200') to at least one decentralized device (101, 102, 100'), wherein the at least one decentralized device is designed to recognize whether it is currently located in the spatial region identified by the identification information, - monitoring the transmission duration of the transmission of the data telegram from the central control apparatus (200, 200') to the at least one decentralized device (101, 102, 100'), and - triggering a predetermined safety reaction if the transmission duration exceeds a predetermined value.

2. The method according to claim 1, wherein the control apparatus (200) and the at least one decentralized device (101, 102) each comprise a timer (240, 140), and wherein the method further comprises the following steps: - synchronizing the timer (240) in the control apparatus (200) with the respective timer (140) in the at least one decentralized device (101, 102), - generating a time stamp by the control apparatus (200) and transmitting the time stamp within the data telegram, the transmission duration being monitored as a function of the time stamp.

3. The method according to claim 2, wherein the timers (240, 140) are synchronized before the at least one decentralized device (101, 102) is put into operation and / or at predetermined intervals of time.

4. The method according to any one of the preceding claims, further comprising the following steps: - establishing a data connection configured for bidirectional communication (510, 520) between the control apparatus (200') and the at least one decentralized device (100'), the data telegram being transmitted unidirectionally from the control apparatus (200') to the at least one decentralized device (100') via this data connection, and - monitoring the transmission quality of the data connection by the control apparatus (200') and / or by the at least one decentralized device (100'), the monitoring of the transmission duration of the transmission of the data telegram taking place as a function of the monitored transmission quality.

5. The method according to any one of the preceding claims, wherein the at least on decentralized device (101, 102, 100') is designed as an automated guided vehicle.

6. The method according to any one of the preceding claims, wherein the transmission of the data telegram takes place via a wireless network.

7. The method according to any one of the preceding claims, wherein the data telegram is used to transmit safety-relevant data.

8. The method according to any one of the preceding claims, wherein a safe communication protocol is used to transmit the data telegram.

9. A control apparatus (200, 200') for controlling a plurality of decentralized devices (101, 102, 100'), comprising: - a means for generating a data telegram for the multicast transmission of data to a group of the plurality of decentralized devices (101, 102, 100'), wherein the devices of the group are located in a defined spatial region, and wherein the data telegram comprises identification information that identifies the defined spatial region, - a means for unidirectionally transmitting the data telegram to at least one decentralized device (101, 102, 100'), wherein the at least one decentralized device is designed to recognize whether it is currently located in the spatial region identified by the identification information, and - a means for monitoring the transmission duration of the unidirectional transmission of the data telegram from the central control apparatus (200, 200') to the at least one decentralized device (101, 102, 100').

10. The control apparatus (200) according to claim 9, wherein the means for monitoring the transmission duration comprises a timer (240) and a means for synchronizing the timer (240) with a timer (140) arranged in the at least one decentralized device (101, 102), and wherein the means for generating the data telegram is designed to generate a time stamp and transmit it within the data telegram.

11. The control apparatus (200') according any one of claims 9 or 10, designed to establish a data connection configured for bidirectional communication (510, 520) with the at least one decentralized device, wherein - the means for unidirectionally transmitting the data telegram is designed for unidirectionally transmitting the data telegram via the data connection, and - the means for monitoring the transmission duration comprises a diagnostic unit (260) that is designed to: - monitor the transmission quality of the data connection configured for bidirectional communication (510, 520), - monitor the transmission duration of the unidirectional transmission of the data telegram as a function of the monitored transmission quality, and - trigger a predetermined safety reaction if the transmission duration exceeds a predetermined value.

12. A device (101, 102), in particular designed as an automated guided vehicle, that can be controlled by a central control apparatus (200), the device being designed to receive a unidirectionally transmitted data telegram for the multicast transmission of data to a group of devices that are located in a defined spatial region, the data telegram comprising identification information that identifies the defined spatial region, from the central control apparatus (200), and the device being designed to recognize whether it is currently located in the spatial region identified by the identification information, and the device comprising: - a means for monitoring the transmission duration of the unidirectional transmission of the data telegram from the central control apparatus (200) to the device (101, 102), and - a means for triggering a predetermined safety reaction if the transmission duration exceeds a predetermined value.

13. The device according to claim 12, wherein the data telegram comprises a time stamp, the device comprises a timer (140) and means for synchronizing the timer with a timer (240) arranged in the central control apparatus (200), and the means for monitoring is designed to monitor the transmission duration as a function of the time stamp contained in the data telegram and using the timer.

14. The device (100') according to any one of claims 12 or 13, designed to establish a data connection configured for bidirectional communication (510, 520) with the central control apparatus (200), via which the data telegram is transmitted, wherein the means for monitoring the transmission duration comprises a diagnostic unit (260) that is designed to: - monitor the transmission quality of the data connection configured for bidirectional communication (510, 520), - monitor the transmission duration of the unidirectional transmission of the data telegram as a function of the monitored transmission quality, and - trigger a predetermined safety reaction if the transmission duration exceeds a predetermined value.

15. A control and data transmission system (10, 20), comprising a control apparatus (200, 200') according to any one of claims 9 to 11, at least one device (101, 102, 100') according to any one of claims 12 to 14, and a communication network via which the control apparatus (200, 200') can transmit data to the at least one device (101, 102, 100').