CN214504203U

CN214504203U - Equipment of PLC multimode extension

Info

Publication number: CN214504203U
Application number: CN202120866153.XU
Authority: CN
Inventors: 胡运德; 马文奎; 张海兵
Original assignee: Beijing Youhang Electromechanical Technology Co ltd
Current assignee: Beijing Youhang Electromechanical Technology Co ltd
Priority date: 2021-04-26
Filing date: 2021-04-26
Publication date: 2021-10-26
Anticipated expiration: 2031-04-26

Abstract

The utility model discloses a PLC multi-module extension device, based on the principle of GPIO and CAN bus communication, all PLC modules are designed based on ARM controllers with the same architecture, each PLC module CAN be used as a CPU functional module, and simultaneously has the function of an extension functional module; the equipment consists of the following two parts: the GPIO bus circuit can realize master-slave or slave-slave interconnection among different PLCs after the current GPIO isolation output interface of the PLC module and the isolation input interface of the next PLC module are connected through a cable; the current PLC module and the subordinate PLC module CAN realize communication interconnection among different PLCs by isolating the CAN bus; all PLC devices use the same power supply and are powered up at the same time. The utility model discloses can solve the technical problem who realizes PLC's multi-module equipment discernment enumeration.

Description

Equipment of PLC multimode extension

Technical Field

The utility model relates to an automatic change control system's improvement technique. In particular to a method for realizing master-slave interconnection expansion of a plurality of PLC modules.

Background

In an automatic control system, in order to meet the actual use requirements of a large number of manufacturers, a Programmable Logic Controller (PLC) should have a function of expanding one or more types of functional modules (a digital module, an analog module, a thermocouple module, and the like) in a cascade manner to provide more acquisition control channels. In this case, a method for implementing master-slave interconnection expansion of a plurality of PLC modules is required, and at the same time, it is also necessary to recognize an abnormal situation occurring in some modules. Common methods for realizing the extension interconnection communication among the PLC modules include an EtherCAT bus, an I/O port, an RS485 bus (PPI protocol, MPI protocol and the like), a CAN bus and the like. These external bus standards specify the connection and communication between the computer and the master and slave devices.

The traditional PLC system generally comprises two basic modules, namely a CPU functional module and an extended functional module, wherein the modules are connected through a communication back plate, and the problems of distance limitation and the like exist. Although the extended function module is based on a general bus protocol, it is of various kinds and inconvenient to identify and manage. Meanwhile, when the master module or the slave module of the PLC fails, the other modules cannot be replaced on site, extra equipment maintenance time is needed, and the system maintenance cost is overlarge.

Disclosure of Invention

The utility model aims at providing a PLC multimode extension's equipment to solve the technical problem who realizes PLC multimode equipment discernment enumeration.

In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

a PLC multi-module extension device is based on the principle of GPIO and CAN bus communication, all PLC modules are designed based on an ARM controller with the same architecture, each PLC module CAN be used as a CPU functional module, and simultaneously has the function of an extension functional module; the equipment consists of the following two parts:

the GPIO bus circuit can realize master-slave or slave-slave interconnection among different PLCs after the current GPIO isolation output interface of the PLC module and the isolation input interface of the next PLC module are connected through a cable;

the current PLC module and the subordinate PLC module CAN realize communication interconnection among different PLCs by isolating the CAN bus; all PLC devices use the same power supply and are powered up at the same time;

the GPIO bus circuit consists of an input IO isolation circuit, an output IO isolation circuit, a level preset circuit and a protection circuit; the input and output IO isolation circuits are all isolated by using an optical coupling relay; the level presetting circuit realizes that the initial levels of the outer side of a user and the inner side of the control are in a fixed state in a mode of pulling up and pulling down a resistor; the protection circuit realizes reverse connection, overcurrent, overvoltage, static electricity and surge protection of signals through the Schottky diode and the TVS tube; the input IO (PE4) and the output IO (PC2) are respectively connected with an input/output IO port of the ARM control chip, the IO _ OUT signal serves as an external output interface of the current module, and the IO _ IN signal is connected with an external input interface IO _ IN of the next cascade module through an interconnection cable. Similarly, the IO _ IN signal is used as an external input/output interface of the current module, and is connected with an external output interface IO _ OUT signal of a cascade module through an interconnection cable.

The CAN bus circuit consists of a CAN driving circuit, a common mode rejection circuit and an impedance matching circuit; the CAN driving circuit adopts a CAN transceiver with iCoupler digital signal isolation and converts the CAN transceiver into physical layer characteristics required by CAN bus specification; the common mode rejection circuit adopts a common mode inductance filter; the impedance matching circuit adopts a resistor to carry out differential impedance matching; the CAN2_ RX and CAN2_ TX are respectively connected with input and output IO ports PB12 and PB13 of an ARM control chip, signals of CAN2L and CAN2H serve as external CAN bus interfaces of a current module, and the external CAN bus interfaces of a previous cascade module and a next cascade module are respectively connected through two interconnection cables, so that two-two interconnection between different PLCs CAN be realized by isolating the CAN buses of the current PLC module and a next PLC module; based on a self-defined CAN bus communication protocol, after the initialization of the CAN master-slave equipment is finished, the CAN slave equipment transmits information step by step through a CAN bus, and finally sends information such as the type of the equipment, the software version number, the hardware version number and the like to the CAN master equipment for storage; the master device senses the current state of the slave device by updating the sequence linked list of the slave device at regular time, and performs data synchronization of the master device and the slave device by using the linked list.

The utility model discloses an advantage and positive effect as follows:

adopt the utility model discloses a PLC multimode piece of equipment based on GPIO and CAN bus has combined traditional meaning "CPU function module" and "extended function module" together, has reduced the module kind, has strengthened the module function. The module and the module determine the master-slave relationship through the GPIO bus, and realize the data synchronization between the master device and the slave device through the CAN bus communication. Based on a novel communication mechanism, the distance limitation of the traditional communication backboard is broken through, and theoretically, long-distance distribution can be realized between master equipment and slave equipment, so that the distributed type is realized in the real sense. Meanwhile, when the field PLC module breaks down, any one master PLC device or slave PLC device can replace other failed devices in time through simple adjustment based on a novel master-slave distinguishing and linked list sequencing synchronization mechanism, so that the system maintenance time is greatly shortened, and the system maintenance cost is reduced.

Drawings

Fig. 1 is the PLC master slave module cascade diagram of the present invention.

Fig. 2 is a circuit diagram of a GPIO bus according to the present invention.

Fig. 3 is a CAN bus circuit of the present invention using a new model.

Detailed Description

The specific structure and the working principle of the utility model are shown in the attached drawings:

referring to fig. 1, after the PLC module 1, the PLC modules 2 and …, and the PLC module n are cascaded by GPIO, in order to ensure that the PLC device can correctly recognize enumeration, the PLC module is cascaded according to fig. 3. All PLC devices use the same power supply and are powered up at the same time.

After the equipment is powered on, the input/output IO on the hardware is high level, a main program runs, and a system is initialized and comprises a global variable, a GPIO port and the like; and then the level of the output IO port is pulled down, and then the delay is carried out for 500 milliseconds, and the level change of the input IO port of the current module is detected. Because the input IO port of the first device is not connected with other devices and is detected to be high level, and the input IO of other devices is pulled to be low level by the previous device connected with the input IO port of the first device, the roles of the master device and the slave device in the CAN linked list CAN be distinguished, namely the first device is the PLC master device and is also the CAN master device; the other devices are the PLC slave station device and the CAN slave station device.

After receiving the appointed pulse signal, the first CAN slave device sends a position request signal to the CAN master device through the CAN bus; after the CAN master device receives the request signal, the CAN master device obtains the position number (namely the request sequence number) of the device by looking up a table and then transmits the position number to the device through a CAN bus; and after receiving the position information, the slave device continues to initialize and sends a scheduled high-low pulse signal to the next CAN slave device connected with the slave device through the output IO port. The second CAN slave device repeats the operation of the previous CAN slave device, completes initialization and sends down pulse signals. And so on until all CAN slaves have received their own sequence numbers from the CAN master. After all CAN master-slave devices are initialized, the information such as the number, the positions and the like of field installation devices is stored in the CAN master devices. When all CAN equipment communicates each time, the communication protocol contains equipment sequence number information of data packet sending and receiving for other equipment to identify and process. The whole enumeration process of the CAN bus device is completed.

As shown in fig. 2. The GPIO bus circuit comprises an input IO isolation circuit, an output IO isolation circuit, a level preset circuit, a protection circuit and the like. The input and output isolation circuits are all isolated by using an optocoupler relay, so that the electrical isolation between the outer side of a user and the inner side of a control is realized, and the anti-interference effect is enhanced; the level presetting circuit realizes that the initial levels of the outer side of the user input and the inner side of the control are in a fixed state in a mode of pulling up and pulling down resistors; the protection circuit realizes the protection of reverse connection, overcurrent, overvoltage, static electricity, surge and the like of signals through the Schottky diode and the TVS tube.

The input IO (PE4) and the output IO (PC2) are respectively connected with an input/output IO port of the ARM control chip, the IO _ OUT signal serves as an external output interface of the current module, and the IO _ IN signal is connected with an external input interface IO _ IN of the next cascade module through an interconnection cable. Similarly, the IO _ IN signal is used as an external input/output interface of the current module, and is connected with an external output interface IO _ OUT signal of a cascade module through an interconnection cable.

After all PLC equipment is powered on at the same moment, the level presetting circuit enables the input/output IO initial state on hardware to be high level, then the main program runs, and the system is initialized; and each module pulls the level of the output IO port low, then delays for 500 milliseconds, and detects the level change of the input IO port of the current module. Because the input IO port of the first device is not connected with other devices and is detected to be high level, and the input IO of other devices is pulled to be low level by the previous device connected with the input IO port of the first device, the roles of the master device and the slave device in the CAN linked list CAN be distinguished, namely the first device is the PLC master device and is also the CAN master device; the other devices are the PLC slave station device and the CAN slave station device.

Referring to fig. 3, the CAN bus circuit is composed of a CAN driving circuit, a common mode rejection circuit, an impedance matching circuit, and the like. The CAN driving circuit adopts a CAN transceiver with iCoupler digital signal isolation and converts the CAN transceiver into physical layer characteristics required by CAN bus specification; the common mode rejection circuit adopts a common mode inductance filter, can effectively reject common mode noise on the high-speed differential signal line, and enhances the EMC performance of the circuit; the impedance matching circuit adopts a 120 ohm resistor for differential impedance matching, and reduces noise caused by reflection of long distance or impedance discontinuity and the like.

The CAN2_ RX and CAN2_ TX are respectively connected with input/output IO ports PB12 and PB13 of the ARM control chip, signals of CAN2L and CAN2H serve as external CAN bus interfaces of the current module, and the external CAN bus interfaces of one cascade module and the next cascade module are respectively connected through two interconnection cables. Therefore, the current PLC module and the subordinate PLC module CAN be interconnected in pairs among different PLCs by isolating the CAN bus. Based on a self-defined CAN bus communication protocol, after the initialization of the CAN master-slave equipment is finished, the CAN slave equipment transmits information step by step through a CAN bus, and finally sends information such as the type of the equipment, the software version number, the hardware version number and the like to the CAN master equipment for storage. Thus, a linked list containing all devices on the CAN link is maintained inside the CAN master device. The master device senses the current state of the slave device by updating the sequence linked list of the slave device at regular time, and performs data synchronization of the master device and the slave device by using the linked list.

Claims

1. A PLC multi-module extension device is based on the principle of GPIO and CAN bus communication, all PLC modules are designed based on an ARM controller with the same architecture, each PLC module CAN be used as a CPU functional module, and simultaneously has the function of an extension functional module; the device is characterized by comprising the following two parts:

the current PLC module and the subordinate PLC module CAN realize communication interconnection among different PLCs by isolating the CAN bus; all PLC devices use the same power supply and are powered up at the same time.

2. The PLC multi-module extension device of claim 1, wherein the GPIO bus circuit is composed of an input IO isolation circuit, an output IO isolation circuit, a level preset circuit and a protection circuit; the input and output IO isolation circuits are all isolated by using an optical coupling relay; the level presetting circuit realizes that the initial levels of the outer side of a user and the inner side of the control are in a fixed state in a mode of pulling up and pulling down a resistor; the protection circuit realizes reverse connection, overcurrent, overvoltage, static electricity and surge protection of signals through the Schottky diode and the TVS tube; the input IO and the output IO are respectively connected with an input/output IO port of the ARM control chip, an IO _ OUT signal is used as an external output interface of the current module, and an external input interface IO _ IN signal of the next cascade module is connected through an interconnection cable; similarly, the IO _ IN signal is used as an external input/output interface of the current module, and is connected with an external output interface IO _ OUT signal of a cascade module through an interconnection cable.

3. The device of claim 1, wherein the CAN bus circuit is composed of a CAN driving circuit, a common mode rejection circuit, and an impedance matching circuit; the CAN driving circuit adopts a CAN transceiver with iCoupler digital signal isolation and converts the CAN transceiver into physical layer characteristics required by CAN bus specification; the common mode rejection circuit adopts a common mode inductance filter; the impedance matching circuit adopts a resistor to carry out differential impedance matching; the CAN2_ RX and CAN2_ TX are respectively connected with input and output IO ports PB12 and PB13 of an ARM control chip, signals of CAN2L and CAN2H serve as external CAN bus interfaces of a current module, and the external CAN bus interfaces of a previous cascade module and a next cascade module are respectively connected through two interconnection cables, so that two-two interconnection between different PLCs CAN be realized by isolating the CAN buses of the current PLC module and a next PLC module; based on a self-defined CAN bus communication protocol, after the initialization of the CAN master-slave equipment is finished, the CAN slave equipment transmits information step by step through a CAN bus, and finally sends information such as the type of the equipment, the software version number, the hardware version number and the like to the CAN master equipment for storage; the master device senses the current state of the slave device by updating the sequence linked list of the slave device at regular time, and performs data synchronization of the master device and the slave device by using the linked list.