Method for operating plurality of radio frequency identification readers and control and monitoring unit for radio frequency identification readers

Abstract

The invention relates to a method for operating a plurality of radio frequency identification readers, each of which is connected to a plurality of antennas. The radio frequency identification readers (R1-R3) are time-synchronized via a communication network (NET). According to the invention, antennas (A11-A14, A21-A24, A31-A34) assigned to different radio frequency identification readers or to the same radio frequency identification reader are determined, the detection areas of which at least partially overlap, and on a graphical user interface of a control and monitoring unit (CFG) connected to the radio frequency identification readers via the communication network, the antennas (A11-A14, A21-A24, A31-A34) are connected to the radio frequency identification readers via the communication network, and the detection areas of the antennas (A11-A14, A21-A24, A31-A34) at least partially overlap. And marking the determined antennas with the at least partially overlapping detection areas as conflicting with each other. In order to use each antenna on the respective radio frequency identification reader for reading and / or writing for a radio frequency identification transponder, at least one cyclically repeated time window (T1-T4) is reserved, said time window being assigned to the respective antenna. In this case, the allocation of mutually conflicting antennas for the same time window is prevented.

Description

Technical Field

[0001] The present invention relates to a method for operating multiple radio frequency identification (RFID) readers, particularly UHF RFID readers, and a control and monitoring unit for RFID readers to perform this method. Background Technology

[0002] A radio transponder can be, for example, an RFID tag (Radio Frequency Identification), which is attached to the transponder for the identification or location of an item. The RFID tag includes a storage unit whose contents can be read, but also modified, using an RFID reader. Typically, at least one identifier is stored in each RFID tag. To read the information stored in the RFID tag, the RFID reader transmits an interrogation signal by generating an electromagnetic alternating field. On one hand, this electromagnetic alternating field can be used to power RFID tags, especially those operating passively and without their own power source. On the other hand, the electromagnetic alternating field can be modulated by the RFID tag to transmit a response signal, for example, by load modulation or changing its antenna impedance.

[0003] Radio transponder systems used in industrial automation systems must meet specific requirements regarding reliable data transmission, the authenticity of transmitted data, and insensitivity to interference transmitters. This is because industrial automation systems are used to monitor, control, and regulate technological processes, particularly in manufacturing, process, and building automation. For example, a jammed or manipulated radio transponder system can have serious consequences, potentially leading to the stagnation of an automated system in the worst-case scenario.

[0004] A method for configuring a communication module for at least one RFID reader connected to a communication network is known from EP 3 291 488 B1. The at least one RFID reader is connected to the communication module via a serial interface. At least communication network address information and configuration information including device type information are stored in a configuration storage unit of the communication module. The configuration information stored in the configuration storage unit of the communication module is transmitted to the at least one RFID reader via the serial interface and stored therein in a preset configuration storage area. When a device using a standby communication module that replaces the existing communication module is started, after a successful validity check, the configuration information stored in the preset configuration storage area of ​​the RFID reader is loaded to configure the standby communication device.

[0005] EP 3 290 948 B1 describes a location detection sensor for a location detection system. The location detection sensor includes first and second radio transponders, each having a transmitting and receiving unit connected to an antenna and a storage unit for persistent data storage. The first radio transponder has a power supply source and can be selectively placed in a static state with reduced energy consumption and in an active operating state with a full range of functions. In the active operating state, at least one radio connection for location detection is established with at least one first radio transponder reader. A second radio transponder, which can be inductively powered by the radio transponder reader, is designed and configured to either place the first radio transponder from a static state to an active operating state upon entering the detection area of ​​the second radio transponder reader, or transmit location information assigned to the second radio transponder to a server of the location detection system via the second radio transponder reader.

[0006] Methods for operating multiple RFID readers are known from US 2006 / 022800 A1 and US 2009 / 256683 A1, respectively, wherein the RFID readers are time-synchronized via a communication network (NET). Here, RFID readers are identified such that their detection areas at least partially overlap.

[0007] UHF-RFID systems operating in the 865 MHz to 928 MHz frequency range offer greater coverage compared to RF-RFID systems operating at 13.56 MHz. If multiple RFID readers or multiple antennas of RFID readers are spatially close to each other, the antenna positioning and orientation must be planned as carefully as possible to avoid mutual interference, especially when reading simultaneously. This problem can be solved by synchronizing the reading process of the RFID readers, for example, using a programmable logic controller (PLC) that controls the RFID readers or using a master RFID reader. However, in this case, synchronization occurs only at the device level, not, for example, per antenna. Furthermore, synchronization is guaranteed only for the length of time during which the respective PLC or master RFID reader can be used without interference.

[0008] As an alternative to synchronization, RFID readers can, in principle, check whether a radio channel is already occupied by other participants before using it, using the CSMA method. However, when accessing a radio channel, collisions can only be identified, not avoided. Furthermore, additional testing for existing radio channel occupancy typically incurs performance penalties. Summary of the Invention

[0009] Therefore, the objective of this invention is to provide a reliable and high-performance method for operating multiple RFID readers and to illustrate a suitable implementation of the method, wherein multiple antennas are respectively connected to the multiple RFID readers.

[0010] This task is accomplished according to the invention by a method having the features described in claim 1 and by a control and monitoring unit for a radio frequency identification reader having the features described in claim 9. Advantageous improvements of the invention are given in the dependent claims.

[0011] Corresponding to the method according to the invention for operating multiple radio frequency identification (RFID) readers, each connected to a multiple antenna, the RFID readers, especially UHF-RFID readers, are time-synchronized via a communication network. Time division multiplexing, particularly Time Division Multiple Access (TDMA), is preferably used in the communication network. Each RFID reader advantageously includes a communication module, which is synchronized via a time synchronization server provided in the communication network, particularly according to Network Time Protocol (NTP) or Precision Time Protocol (PTP).

[0012] According to the present invention, antennas assigned to different RFID readers or the same RFID reader are determined, and the detection areas of these antennas at least partially overlap. Partial overlap of the detection areas of multiple antennas is particularly evident when signals exceeding preset received field strength thresholds from different antennas are received at at least one location. Antennas with at least partially overlapping detection areas are determined during the listen-before-speak operation mode of the antenna or RFID reader.

[0013] Antennas with at least partially overlapping detection areas are marked as conflicting according to the invention on the graphical user interface of a control and monitoring unit connected to the RFID reader via the communication network. The control and monitoring unit advantageously provides configuration tools for the RFID reader.

[0014] To enable the use of each antenna on the corresponding RFID reader to read or write to the RFID transponder, at least one cyclically repeating time window is reserved for each antenna. Preferably, the cyclically repeating time window is reserved for the antennas of the RFID reader by means of a control and monitoring unit.

[0015] These time windows, according to the present invention, are synchronized with time information, particularly NTP or PTP timestamps, within the communication network. Furthermore, it prevents conflicting antennas from being assigned to the same time window. In this way, reliable and high-performance synchronization of RFID readers can be achieved, and access conflicts can be avoided at the antenna level. The present invention is particularly robust against the failure of programmable logic controllers or primary RFID readers used as alternatives for synchronization, as is commonly the case to date. In contrast, redundant time synchronization servers are typically used in communication networks.

[0016] Corresponding to a particularly preferred design of the invention, the antennas of the RFID readers are visualized in a grouped manner within a collision matrix on the graphical user interface of the control and monitoring unit, according to the respective RFID readers. Here, each antenna is assigned a column and a row within the collision matrix. Advantageously, conflicting antennas are graphically highlighted within the collision matrix. This enables particularly simple and effective control over possible collision situations.

[0017] Similarly, preferably on the graphical user interface of the control and monitoring unit, the allocation of periodically repeating time windows to the antennas of the corresponding RFID readers is visualized in groups within the time window antenna matrix. Here, each time window is assigned a column or row within the time window antenna matrix, and each antenna is correspondingly assigned a row or column within the time window antenna matrix. Therefore, conflicting antennas can be graphically highlighted within the time window antenna matrix, thereby enabling simple control over the allocation of critical time windows.

[0018] The control and monitoring unit for a radio frequency identification (RFID) reader according to the present invention is configured to perform the method according to the above embodiment and includes a graphical user interface. Furthermore, the control and monitoring unit is configured to determine antennas assigned to different RFID readers or the same RFID reader, the detection areas of which at least partially overlap, and the determined antennas and detection areas that at least partially overlap on the graphical user interface are marked as conflicting.

[0019] Furthermore, the control and monitoring unit is configured to reserve at least one periodically repeating time window for each antenna on the respective RFID reader to read or describe the RFID transponder, and allocate it to the respective antenna. Finally, the control and monitoring unit is configured to prevent conflicting antennas from being allocated the same time window. Attached Figure Description

[0020] The invention will now be described in more detail with reference to the accompanying drawings and embodiments.

[0021] Figure 1The diagram shows an assembly having multiple RFID readers and a control and monitoring unit connected to the RFID readers via a communication network, with multiple antennas connected to each of the RFID readers. Figure 2 The collision matrix, visualized on the graphical user interface of the control and monitoring unit, is shown to represent antennas that may be interfering with each other. Figure 3 The time window antenna matrix is ​​visualized on the graphical user interface of the control and monitoring unit, used to control the allocation of time slots and the use of antennas. Detailed Implementation

[0022] exist Figure 1 The components shown include multiple RFID readers R1-R3 interconnected via a communication network NET, each of which is connected to multiple antennas (A11-A14, A21-A24, A31-A34). Time division multiplexing, such as Time Division Multiple Access (TDMA), is used in the communication network NET. Each RFID reader R1-R3 includes a communication module, which is synchronized via a time synchronization server NTP located in the communication network NET. In this way, the RFID readers perform time synchronization. This can be achieved, in particular, according to the Network Time Protocol (NTP) or the Precision Time Protocol (PTP).

[0023] In addition, a control and monitoring unit (CFG) is provided for the RFID readers R1-R3, which is connected to the RFID readers R1-R3 via a communication network NET. The control and monitoring unit (CFG) specifically provides configuration tools for the RFID readers R1-R3.

[0024] To avoid interference or functional problems caused by the mutual influence of antennas A11-A14, A21-A24, and A31-A34 when reading or describing RFID transponders, it is determined that the detection areas of antennas A11-A14, A21-A24, and A31-A34 assigned to different RFID readers R1-R3 or the same RFID reader R1-R3 at least partially overlap. This adverse effect is exacerbated when RFID readers R1-R3 are UHF RFID readers. Partial overlap of the detection areas of multiple antennas is particularly noticeable when signals exceeding a preset received field strength threshold are received from different antennas A11-A14, A21-A24, and A31-A34 at at least one location.

[0025] As in Figure 1As indicated by dashed or dotted lines around the paired antennas that adversely affect each other, the detection areas of antennas A13 and A22 overlap in this embodiment. Further overlap exists between antennas A14 and A21, between antennas A23 and A32, and between antennas A24 and A31. This overlap may cause the RFID transponder to be unable to read correctly using the associated antennas A13 / A22, A14 / A21, A23 / A32, and A24 / A31. Antennas A13 / A22, A14 / A21, A23 / A32, and A24 / A31 with at least partially overlapping detection areas can, for example, be identified during the listen-before-speak operation of antennas A11-A14, A21-A24, A31-A34, or RFID readers R1-R3.

[0026] according to Figure 2 The detection areas that at least partially overlap on the graphical user interface of the control and monitoring unit (CFG) are marked as conflicting antennas A13 / A22, A14 / A21, A23 / A32, and A24 / A31. Therefore, on the graphical user interface of the CFG, the antennas A11-A14, A21-A24, and A31-A34 of the RFID readers R1-R3 are visualized in groups within the conflict matrix M1 according to the corresponding RFID readers R1-R3. Here, each antenna A11-A14, A21-A24, and A31-A34 is assigned columns and rows within the conflict matrix M1. Conflicting antennas A13 / A22, A14 / A21, A23 / A32, and A24 / A31 are graphically highlighted within the conflict matrix M1, for example, by using different colors or brightness or by using additional symbols to represent overlap.

[0027] To read or write to an RFID transponder using each antenna (A11-A14, A21-A24, A31-A34) on the corresponding RFID readers R1-R3, corresponding to Figure 3At least one periodically repeating time window T1-T4 is reserved for each antenna, which is assigned to the corresponding antennas A11-A14, A21-A24, and A31-A34. Here, the time windows T1-T4 are synchronized with time information within the communication network NET, particularly NTP or PTP timestamps. This is preferably performed periodically by the RFID readers R1-R3, for example, once every few minutes or hours. In this embodiment, the periodically repeating time windows T1-T4 for the antennas A11-A14, A21-A24, and A31-A34 for the RFID readers R1-R3 are reserved using a control and monitoring unit CFG. Furthermore, the control and monitoring unit CFG prevents conflicting antenna assignments A13 / A22, A14 / A21, A23 / A32, and A24 / A31 to the same time window T1-T4.

[0028] according to Figure 3 On the graphical user interface of the control and monitoring unit CFG, the allocation of periodically repeating time windows T1-T4 to antennas A11-A14, A21-A24, and A31-A34 of RFID readers R1-R3 is visualized in groups within the time window antenna matrix M2 according to the corresponding RFID readers R1-R3. In this embodiment, each time window T1-T4 is assigned a column within the time window antenna matrix M2, while each antenna (A11-A14, A21-A24, A31-A34) is assigned a row within the time window antenna matrix M2. Similar to the aforementioned implementation, conflicting antennas A13 / A22, A14 / A21, A23 / A32, and A24 / A31 are graphically highlighted within the time window antenna matrix M2. Figure 3 The alternative embodiment shown can assign rows within the time window antenna matrix M2 to each time window T1-T4, and columns within the time window antenna matrix M2 to each antenna A11-A14, A21-A24, and A31-A34.

[0029] According to Figure 3As can be seen from the time window antenna matrix M2 shown, the conflicting antennas A13 / A22, A14 / A21, A23 / A32, and A24 / A31 are respectively assigned different time windows T1-T4 due to the blocking described above. Therefore, time windows T1 and T3 are assigned to antenna A13, while time windows T2 and T4 are complementaryly assigned to antenna A22. Similarly, time windows T1 and T3 are assigned to antenna A14, while time windows T2 and T4 are complementaryly assigned to antenna A21. Furthermore, time windows T2 and T4 are assigned to antenna A23, while time windows T1 and T3 are complementaryly assigned to antenna A32. Therefore, time windows T2 and T3 are assigned to antenna A24, while time windows T1 and T4 are complementaryly assigned to antenna A31. Because corresponding to... Figure 2 Antennas A11-A12 and A33-A34 do not conflict with other antennas, so these antennas can be allocated the entire time window T1-T4. Figure 3 The allocations shown are merely exemplary in order to avoid being based on Figure 2 The conflict. Therefore, in addition to Figure 3 Many other allocations besides those shown are feasible.

Claims

1. A method for operating multiple radio frequency identification (RFID) readers, each of which is connected to multiple antennas, wherein, - The RFID readers (R1-R3) are synchronized in time via a communication network (NET). - Antennas (A11-A14, A21-A24, A31-A34) assigned to different RFID readers and / or the same RFID readers are determined, wherein the detection areas of the antennas at least partially overlap. Its features are, - During the listen-before-speak operation mode of the antenna and / or the RFID reader (R1-R3), determine the antenna (A11-A14, A21-A24, A31-A34) with at least partially overlapping detection areas. - On the graphical user interface of the control and monitoring unit (CFG) connected to the RFID reader via the communication network, antennas with at least partially overlapping detection areas are marked as conflicting. - In order to use each antenna on the corresponding RFID reader for reading and / or writing to the RFID transponder, at least one cyclically repeating time window (T1-T4) is reserved for each antenna. - Synchronize the time window with the time information within the communication network. - Prevent conflicting antennas from being assigned to the same time window.

2. The method according to claim 1, wherein, When signals exceeding a preset received field strength threshold are received from different antennas at at least one location, there is partial overlap of the detection areas of multiple antennas (A11-A14, A21-A24, A31-A34).

3. The method according to any one of claims 1 or 2, wherein, The radio frequency identification (RFID) readers (R1-R3) are ultra-high frequency RFID readers.

4. The method according to any one of claims 1 to 3, wherein, On the graphical user interface of the control and monitoring unit (CFG), the antennas (A11-A14, A21-A24, A31-A34) of the RFID readers (R1-R3) are visualized in groups in the collision matrix (M1) according to the corresponding RFID readers, wherein each antenna is assigned a column and a row in the collision matrix, and wherein mutually conflicting antennas are graphically highlighted in the collision matrix.

5. The method according to claim 4, wherein, On the graphical user interface of the control and monitoring unit (CFG), the allocation of periodically repeating time windows (T1-T4) to the antennas (A11-A14, A21-A24, A31-A34) of the RFID readers (R1-R3) is visualized in groups according to the corresponding RFID readers in the time window antenna matrix (M2), wherein each time window is assigned a column or row within the time window antenna matrix, and each antenna is assigned a row or column within the time window antenna matrix, and wherein conflicting antennas are graphically highlighted within the time window antenna matrix.

6. The method according to any one of claims 1 to 5, wherein, The control and monitoring unit (CFG) reserves the periodically repeating time window (T1-T4) for the antennas (A11-A14, A21-A24, A31-A34) of the radio frequency identification reader (R1-R3).

7. The method according to any one of claims 1 to 6, wherein, The control and monitoring unit (CFG) provides configuration tools for the radio frequency identification readers (R1-R3).

8. The method according to any one of claims 1 to 7, wherein, The communication network (NET) employs a time division multiplexing method, particularly time division multiple access, and wherein the radio frequency identification readers (R1-R3) each include a communication module that is synchronized via a time synchronization server (NTP) provided within the communication network, particularly according to a network time protocol or a precision time protocol.

9. A control and monitoring unit for a radio frequency identification reader, configured to perform the method according to any one of claims 1 to 8, wherein, The control and monitoring unit includes a graphical user interface and is configured to, - Identify antennas (A11-A14, A21-A24, A31-A34) assigned to different RFID readers (R1-R3) and / or the same RFID reader, wherein the detection areas of the antennas at least partially overlap, wherein the antennas (A11-A14, A21-A24, A31-A34) with at least partially overlapping detection areas are identified during the listen-before-speak operation mode of the antennas and / or the RFID readers (R1-R3). - On the graphical user interface, antennas with at least partially overlapping detection areas are marked as conflicting. - In order to use each antenna on the corresponding RFID reader for reading and / or writing to the RFID transponder, at least one cyclically repeating time window (T1-T3) is reserved respectively, and said time window is assigned to the corresponding antenna. - Prevent conflicting antennas from being assigned to the same time window.

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