Letter sorting machine control system based on EtherCAT double-link redundancy

Abstract

The invention provides a letter sorting machine control system based on EtherCAT double-link redundancy. The letter sorting machine control system comprises a main controller, a redundancy switching unit, a distributed slave station and branch control module, a belt transmission module and a grid display module. The main controller adopts multi-core CPU function isolation, binds different tasks to corresponding cores and allocates execution cycles; the redundancy switching unit constructs a double-link annular redundancy network, automatic switching is achieved when links are abnormal, and communication stability is guaranteed; the distributed slave stations are provided with terminal modules according to needs, are integrated in slave station boxes and are flexibly connected to execution components of all functional areas. And the lattice display module adopts a group leader-group member structure, so that the load of a main network is reduced. The system sets priorities for EtherCAT network groups based on signal real-time performance, realizes IO signal rapid response, and supports flexible expansion of slave station boxes. The reliability, the real-time performance and the expansibility of letter sorting control are improved, the method is suitable for a high-speed sorting scene, and the efficient operation requirement of the postal logistics industry is met.

Description

Technical Field

[0001] This invention belongs to the field of logistics control technology, and more specifically, relates to a letter sorting machine control system based on EtherCAT dual-link redundancy. Background Technology

[0002] As sorting equipment in the postal logistics industry, mail sorting machines affect mail processing efficiency and circulation quality. Their operation is characterized by high processing speed, high frequency of operation, and stringent requirements for mail tracking accuracy and synchronous control of multiple components. The industry has extremely high demands for the reliability, real-time performance, scalability, and ease of maintenance of sorting machine control systems.

[0003] Currently, most existing letter sorting machine control systems use ISA bus technology or centralized IO board control architecture, lacking an effective link redundancy architecture. Traditional buses often use a single-link serial networking method. Once a connection is lost at some point in the line or a fault occurs in an intermediate module, it will directly lead to the paralysis of the entire downstream control system, making it impossible to carry out sorting operations normally. This not only affects processing efficiency but also incurs high downtime maintenance costs. Furthermore, as letter sorting speeds continue to increase, traditional architectures struggle to achieve microsecond-level synchronous control of sorting actions, making them prone to letter missorting, letter jamming, and other faults. At the same time, traditional solutions cannot flexibly adapt to the needs of increasing or decreasing the number of sorting machine slots. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a letter sorting machine control system based on EtherCAT dual-link redundancy. This system solves the technical problem that in the prior art, traditional sorting machine control systems typically use a single-link serial connection. If a disconnection occurs at some point in the line or a fault occurs in an intermediate module, the downstream system will be paralyzed, resulting in high downtime maintenance costs and poor scalability.

[0005] The purpose and effectiveness of the letter sorting machine control system based on EtherCAT dual-link redundancy of the present invention are achieved by the following specific technical means: The EtherCAT dual-link redundancy-based letter sorting machine control system includes a main controller, redundant switching unit, distributed slave station, branch control module, belt conveyor module and grid display module. The main controller is used for logic control and bus scheduling. It establishes communication connections with the distributed slave stations through redundant switching units and issues control commands to the distributed slave stations. The distributed slave stations are used to receive control commands from the main controller, drive the branch control module, belt conveyor module, and grid display module to perform corresponding actions, and collect the operating status data of each module and send it back to the main controller.

[0006] The above technical solution further includes: the main controller adopts an industrial controller based on PC architecture, runs a real-time operating system, and performs functional isolation through multi-core CPUs, binding IO scanning tasks, whole machine control logic, multi-serial communication, and SCADA monitoring tasks to different CPU cores, and allocating different task execution cycles as needed.

[0007] The above technical solution further includes: the redundant switching unit is used to construct a ring redundant network, connecting the main controller and distributed slave stations. The redundant switching unit includes multiple downlink ports and at least one uplink port. The main controller is connected to the uplink port of the redundant switching unit, and two independent links are led out from the downlink ports. Each link is cascaded through several distributed slave stations and returns to the redundant switching unit through the end slave station to form a ring network. When an anomaly such as a link disconnection is detected, the redundant switching unit automatically switches links for communication.

[0008] The above technical solution further includes: the distributed slave station adopts EtherCAT coupler and terminal module, and the input module, output module, communication module and pulse module are configured according to the needs of different functional areas of the letter sorting machine. The terminal module is connected to the EtherCAT ring redundant network through the slave station coupler. The distributed slave stations are integrated into the slave station box, which also includes a switching power supply, a miniature circuit breaker, a branch control module, and the execution components of the belt conveyor module, which are connected to the terminal module via an RS485 bus.

[0009] The above technical solution further includes: the branch control module is used to drive the branch mechanism to act according to the trigger signal and switch the letter transmission path. The branch control module includes a trigger signal port, a fault signal port, an RS485 communication port, a DIP address port and a running indicator light. It connects to the corresponding distributed slave station through the RS485 communication port, receives control commands issued by the distributed slave station and feeds back the fault status.

[0010] The above technical solution further includes: the belt transmission module is used to drive the belt operation of each module of the letter sorting machine. The belt transmission module includes a three-phase asynchronous motor and a frequency converter. The frequency converter supports an RS485 communication port. The corresponding distributed slave station is connected through this port to receive control commands from the distributed slave station and drive the three-phase asynchronous motor to adjust the belt transmission speed.

[0011] The above technical solution further includes: the grid display module is used for grid information display and grid indicator light control, the grid display module includes a grid LCD display control circuit board and a display screen, each circuit board controls 2 display screens and 6 indicator lights; The grid display module adopts a leader-member structure, with 10 LCD display control circuit boards forming a group. Each group has a leader board, which communicates with the main controller via TCP / IP. The LCD display control circuit boards within the group are cascaded via CAN bus.

[0012] The above technical solution further includes: grouping the EtherCAT network based on the real-time requirements of different signals, setting different priorities for each group of signals to ensure fast response of IO signals, with an average response time of less than 520 microseconds for IO signals; The slave station box of the distributed slave station is used to configure the number of terminal modules and branch control modules connected according to different functional requirements of the system.

[0013] Compared with the prior art, the present invention has the following beneficial effects: An EtherCAT dual-link ring redundant network is constructed using redundant switching units. The main controller is connected to the uplink port of the redundant switching unit, and two independent links are led out from the downlink ports and cascaded through distributed slave stations to form a closed loop. When any node or cable in the communication link is disconnected or an intermediate module fails, the redundant switching unit can automatically switch the transmission path to ensure normal communication between the main controller and the distributed slave stations, avoiding unexpected downtime of the entire line. This reduces the impact of single-point failures on the overall system operation, minimizes losses from downtime maintenance, ensures continuous and stable letter sorting operations, and solves the problem that the traditional single-link serial architecture of sorting machine control systems is prone to system paralysis due to disconnection or module failure.

[0014] Leveraging the high-speed synchronization mechanism of the EtherCAT bus itself, and combined with the multi-core CPU functional isolation design of the main controller, different tasks such as IO scanning, overall control logic, and multi-serial communication are bound to independent CPU cores, with execution cycles allocated as needed. Simultaneously, the EtherCAT network is grouped based on the real-time requirements of different signals, and signal priorities are set to ensure rapid IO signal response. This multi-dimensional real-time optimization design enables precise tracking of high-speed flowing letters and synchronous control of each execution module, avoiding letter misclassification and jamming caused by synchronization delays, thus improving the stability and accuracy of the sorting process.

[0015] In terms of cabling, the system uses standard industrial Ethernet to connect the slave stations distributed in various functional areas in series, replacing the traditional complex centralized parallel cabling method. This reduces cable usage, lowers cable procurement and construction costs, and also reduces external interference during long-distance signal transmission, improving signal transmission accuracy. For maintenance, the distributed slave stations are integrated within the slave station boxes. The system has self-diagnostic and breakpoint location functions, enabling rapid fault location without manual point-by-point troubleshooting, shortening troubleshooting and repair time, and reducing maintenance difficulty and costs. In terms of expansion, adding a new sorting slot only requires connecting the new distributed slave station at the end and completing the software configuration; no changes to the main trunk line are needed. Furthermore, the slave coupler supports flexible combinations of various functional terminal modules, allowing configuration adjustments based on the needs of different functional areas, adapting to scenarios involving increases or decreases in the number of sorting slots and changes in control requirements. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of the present invention; Figure 2 This is an architecture diagram of the main controller and redundant switching unit in this invention. Detailed Implementation

[0017] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the technical solutions of the present invention, but should not be used to limit the scope of protection of the present invention.

[0018] Example: As attached Figures 1 to 2 As shown: This invention provides a letter sorting machine control system based on EtherCAT dual-link redundancy, including a main controller, redundant switching unit, distributed slave station, branch control module, belt conveyor module and grid display module; The main controller is responsible for the logic control and bus scheduling of the entire system. It connects to the uplink port of the redundant switching unit and establishes a stable communication connection with the distributed slave stations through the dual-link ring redundant network constructed by the redundant switching unit. It issues targeted control commands to the distributed slave stations in different functional areas. The commands include path switching commands for the branch control module, speed adjustment commands for the belt conveyor module, and information display and indicator light control commands for the grid display module. The distributed slave station receives control commands from the main controller, drives the branch control module to quickly switch the letter transmission path according to the trigger signal, drives the frequency converter of the belt conveyor module to adjust the speed of the three-phase asynchronous motor to control the belt conveying rate, and drives the grid display module to display grid information and control the on / off state of the corresponding indicator lights according to the instructions. At the same time, the distributed slave station collects fault signals from the branch control module, operating status signals from the belt conveyor module, and working feedback signals from the grid display module through its own configured input module, and sends these collected operating status data of each module back to the main controller in real time. This provides data support for the main controller to adjust the control strategy, realizing real-time control and status feedback of the letter sorting process.

[0019] The main controller adopts a PC-based industrial controller, using a Beckhoff C6930 industrial computer. Functional isolation is achieved through multi-core CPUs. To meet the control requirements of the letter sorting machine, the highly real-time IO scanning task is bound to a dedicated CPU core, protecting it from interference from non-real-time tasks such as interface refreshes, ensuring rapid IO signal acquisition and response. The overall machine control logic task is bound to another CPU core, which handles the overall letter sorting process instructions and coordinates the management of the branch control module, belt conveyor module, and grid display module. Multi-serial communication tasks are bound to a third CPU core, which handles data interaction across approximately 48 serial ports, enabling the transmission of instructions and status data between the main controller and each distributed slave station. The system binds the SCADA monitoring task to the fourth CPU core. This core is responsible for data communication with the host information system and the SCADA monitoring system, providing real-time feedback on the system's operating status and receiving scheduling instructions from the host system. It also allocates different task execution cycles to different CPU cores as needed. The IO scan task has a short execution cycle to ensure timely signal acquisition. The execution cycle of the overall machine control logic task is adapted to the frequency of letter sorting operations. The execution cycles of the multi-serial communication task and the SCADA monitoring task are reasonably set according to the data transmission volume. Through this multi-core task isolation and execution cycle allocation method, each task can run independently without interference, improving the overall real-time performance and stability of the system and meeting the requirements of high-speed letter sorting machines for control accuracy and response speed.

[0020] The redundant switching unit uses a Beckhoff CU2508 port multiplier. The redundant switching unit is configured with one uplink port and eight downlink ports to construct an EtherCAT ring redundant network, connecting the master controller and distributed slave stations. The X102 port of the master controller is defined as the EtherCAT master port and connects to the uplink port of the redundant switching unit. Two independent links are led out from the downlink port of the redundant switching unit. The first link starts from the X1 port of the redundant switching unit, sequentially connecting several distributed slave stations, and then returning to the X2 port of the redundant switching unit via the OUT port of the last distributed slave station. The second link starts from the X3 port of the redundant switching unit, and so on... The system is then connected in series with another group of distributed slave stations. The OUT ports of the last distributed slave stations in this group are connected back to the X4 port of the redundant switching unit. Each of the two links forms a closed-loop structure, together forming a dual-link ring redundant network. During operation, the redundant switching unit monitors the communication status of the two links in real time. When any abnormality such as node failure or cable disconnection is detected in either link, causing communication interruption, the redundant switching unit automatically switches to another normal link for communication. This ensures that the instruction transmission and data interaction between the main controller and the distributed slave stations are uninterrupted, maintains the normal operation of each module of the system, reduces the risk of system downtime due to single point of failure, and improves the reliability of system operation.

[0021] The distributed slave stations employ EtherCAT couplers and terminal modules, with Beckhoff EK1100 selected as the slave coupler. This coupler is responsible for converting the EtherCAT bus protocol to the internal E-bus protocol. Corresponding terminal modules are configured according to the needs of different functional areas of the mail sorting machine. The slave station in the supply-mail separation area is equipped with a digital input module to collect signals from the manual operation panel and the supply-mail sensor, and a digital output module to drive the supply-mail separation actuator. The slave station in the non-standard rejection area is additionally equipped with a communication module for data interaction with the image acquisition equipment. The slave station in the sorting area is equipped with a pulse module for precise triggering of sorting actions. All terminal modules are connected to the slave coupler via the E-bus backplane bus and connected to the Et... herCAT ring redundancy network; distributed slave stations are integrated into the slave station box, which also includes a switching power supply and miniature circuit breakers. The switching power supply provides a stable operating voltage for all modules in the slave station box, and the miniature circuit breakers automatically disconnect when the circuit is overloaded or short-circuited, protecting the electrical components in the slave station box from damage. The trigger signal port and fault signal port of the branch control module are connected to the digital input / output terminal module, and the frequency converter of the belt conveyor module is connected to the communication terminal module via RS485 bus. Through this connection method, the distributed slave station can issue commands and acquire status data to the branch control module and the belt conveyor module. At the same time, the number and type of terminal modules in the slave station box can be increased or decreased according to the control requirements of different functional areas, so as to realize the flexible adjustment of control functions.

[0022] The branch control module drives the branching mechanism to switch the letter transmission path based on trigger signals issued by the distributed slave station, ensuring that the letter is accurately delivered to the designated slot. The branch control module includes a trigger signal port, a fault signal port, an RS485 communication port, a DIP switch address port, and a running indicator light. The trigger signal port connects to the distributed slave station's digital output module to receive the electrical signal driving the branching mechanism. The fault signal port connects to the distributed slave station's digital input module to collect real-time fault information such as jamming and power failure of the branching mechanism. The RS485 communication port connects to the corresponding distributed slave station's communication terminal module for data interaction with the distributed slave station. The code address port is used to manually set the unique identification address of the module, avoiding address conflicts when multiple branch control modules are connected to the same network. The operation indicator light displays the working status of the module through different colored lights. Green light indicates that the module is operating normally, and red light indicates that the module has failed, which makes it easy for on-site personnel to quickly identify the module's operating status. The branch control module receives control commands from the distributed slave station through the RS485 communication port and drives the branch mechanism to complete the path switching action according to the commands. At the same time, it feeds back the fault status collected by the fault signal port to the distributed slave station through this port, and then the distributed slave station sends the fault information back to the main controller, providing a basis for the main controller to adjust the control strategy.

[0023] The belt conveyor module drives the belts of various functional modules of the letter sorting machine, providing power for the flow of letters in stages such as supply and delivery separation, non-standard rejection, lifting and distribution, and grid conveying. This ensures that letters are stably transported along a preset path. The belt conveyor module includes a three-phase asynchronous motor and a frequency converter. The three-phase asynchronous motor directly drives the belt, while the frequency converter adjusts the power supply frequency of the motor, thereby changing the motor speed to flexibly adjust the belt conveyor speed. The frequency converter supports an RS485 communication port, which connects to the communication terminal module of the corresponding distributed slave station. The frequency converter receives control commands from the distributed slave station through this communication link; these commands include belt start / stop signals. Based on the speed adjustment parameters, the frequency converter adjusts the output frequency according to the instructions, driving the three-phase asynchronous motor to operate at the set speed, thereby adjusting the belt conveyor speed to adapt to the speed requirements of different sorting stages. For example, the belt speed in the letter separation stage needs to match the rhythm of letter single-seal separation, and the belt speed in the sorting conveyor stage needs to match the operating frequency of the shunting mechanism. At the same time, the frequency converter can collect the operating status data of the three-phase asynchronous motor, including motor current, speed and other information, and feed this data back to the distributed slave station through the RS485 communication port. The distributed slave station then sends the data back to the main controller, which allows the main controller to monitor the operating status of the belt conveyor module in real time and promptly detect abnormalities such as motor overload and belt slippage.

[0024] The sorting compartment display module is used for displaying information about the sorting compartments and controlling the indicator lights. It provides on-site staff with key information such as the compartment number, corresponding sorting destination, and the number of letters temporarily stored. Simultaneously, the indicator lights indicate the compartment's status (empty, full, faulty), assisting staff in efficiently completing letter sorting and transfer operations. The module includes a sorting compartment LCD display control circuit board and a display screen. Each circuit board controls two display screens and six indicator lights. The display screens show various text and label information for the compartments, and the six indicator lights, through different on / off states, correspond to different working states of the compartments, facilitating quick identification by personnel. The sorting compartment display module adopts a team leader-team member structure, with each team leader controlling 10 LCD display circuits. The boards are grouped together, with a group leader board in each group. The group leader board connects to a gigabit switch via TCP / IP and communicates with the main controller. It receives display content update commands and indicator light control commands from the main controller, and summarizes the operating status data of each board in the group and feeds it back to the main controller. The LCD display control boards in the group are cascaded via CAN bus. The group leader board can synchronously send control commands to all member boards in the group via CAN bus, realizing unified control of grid display and indicator light status within the group. This structure eliminates the need for each board to establish a separate communication connection with the main controller, effectively reducing the data transmission load of the main network, improving the overall communication efficiency of the system, and facilitating batch management and maintenance of modules.

[0025] Based on the real-time requirements of different signals, the EtherCAT network is grouped. High-priority control signals, such as trigger signals from the branch control module and speed adjustment signals from the belt conveyor module, are grouped into a high-priority group. Signals with lower real-time requirements, such as status feedback signals from the grid display module and some environmental monitoring signals, are grouped into a low-priority group. Different priorities are assigned to each group to ensure that high-priority signals occupy network bandwidth first for transmission, avoiding interference from low-priority signals. This guarantees rapid response of I / O signals, meeting the stringent requirements of high-speed mail sorting machines for synchronization of actions across all execution modules. The average response time of I / O signals is less than 520 microseconds. The distributed slave station's slave box integrates an EtherCAT coupler, switching power supply, and... Basic components such as miniature circuit breakers are used to flexibly configure the number of terminal modules and branch control modules connected according to different functional needs of the system. For the slave box of the supply and signal separation functional area, more digital input modules can be configured to collect signals from the manual operation panel and the supply and signal sensors. For the slave box of the sorting area, more digital output modules can be configured and the number of branch control modules connected can be increased to drive the branching mechanism of multiple sorting areas. For the slave box of the non-standard rejection functional area, an additional communication module can be configured to realize data interaction with the image acquisition equipment. This flexible configuration method can adapt to the control needs of different functional areas of the letter sorting machine without changing the overall system architecture, and at the same time, it is easy to expand and adjust in the future according to the increase or decrease of the number of sorting slots or functional upgrades.

[0026] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A letter sorting machine control system based on EtherCAT dual-link redundancy, characterized in that: It includes a main controller, redundant switching unit, distributed slave stations, branch control module, belt conveyor module and grid display module; The main controller is used for logic control and bus scheduling. It establishes communication connections with the distributed slave stations through redundant switching units and issues control commands to the distributed slave stations. The distributed slave stations are used to receive control commands from the main controller, drive the branch control module, belt conveyor module, and grid display module to perform corresponding actions, and collect the operating status data of each module and send it back to the main controller.

2. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: The main controller adopts an industrial controller based on PC architecture, runs a real-time operating system, and uses multi-core CPUs for functional isolation. It binds IO scanning tasks, whole machine control logic, multi-serial communication, and SCADA monitoring tasks to different CPU cores and allocates different task execution cycles as needed.

3. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: The redundant switching unit is used to construct a ring redundant network, connecting the main controller and distributed slave stations. The redundant switching unit includes multiple downlink ports and at least one uplink port. The main controller is connected to the uplink port of the redundant switching unit, and two independent links are led out from the downlink ports. Each link is cascaded through several distributed slave stations and returns to the redundant switching unit through the end slave station to form a ring network. When an anomaly such as a link disconnection is detected, the redundant switching unit automatically switches links for communication.

4. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: The distributed slave stations use EtherCAT couplers and terminal modules. Input modules, output modules, communication modules, and pulse modules are configured according to the needs of different functional areas of the letter sorting machine. All terminal modules are connected to the EtherCAT ring redundant network through slave station couplers. The distributed slave stations are integrated into the slave station box, which also includes a switching power supply, a miniature circuit breaker, a branch control module, and the execution components of the belt conveyor module, which are connected to the terminal module via an RS485 bus.

5. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: The branch control module is used to drive the branch mechanism to operate according to the trigger signal and switch the letter transmission path. The branch control module includes a trigger signal port, a fault signal port, an RS485 communication port, a DIP address port and a running indicator light. It connects to the corresponding distributed slave station through the RS485 communication port, receives control commands issued by the distributed slave station and reports the fault status.

6. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: The belt conveyor module is used to drive the belts of each module of the letter sorting machine. The belt conveyor module includes a three-phase asynchronous motor and a frequency converter. The frequency converter supports an RS485 communication port, through which it connects to the corresponding distributed slave station, receives control commands from the distributed slave station, and drives the three-phase asynchronous motor to adjust the belt conveyor speed.

7. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: The grid display module is used for grid information display and grid indicator light control. The grid display module includes a grid LCD display control circuit board and a display screen. Each circuit board controls 2 display screens and 6 indicator lights. The grid display module adopts a leader-member structure, with 10 LCD display control circuit boards forming a group. Each group has a leader board, which communicates with the main controller via TCP / IP. The LCD display control circuit boards within the group are cascaded via CAN bus.

8. The letter sorting machine control system based on EtherCAT dual-link redundancy according to claim 1, characterized in that: Based on the real-time requirements of different signals, the EtherCAT network is grouped, and different priorities are set for each group of signals to ensure fast response of IO signals. The average response time of IO signals is less than 520 microseconds. The slave station box of the distributed slave station is used to configure the number of terminal modules and branch control modules connected according to different functional requirements of the system.

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