WO2021112710A1 - System for automatically configuring a modular plc - Google Patents

Abstract

The invention relates to programmable logic controllers (PLCs) constituting an automated control system that operates according to set algorithms. A system for automatically configuring a modular PLC comprises a processor module connected to a common data bus together with an expansion module, wherein the common data bus is formed by the combination of portions of an internal bus disposed inside each module, and of switching devices that allow signals to transit between modules. The common data bus comprises a service bus for addressing connected devices, a data transfer bus, a line for transmitting alarm signals, and a line for transmitting a "reset" command. The service bus inside each module comprises a re-driver that performs the function of interrupting the transfer of data via the service bus in response to a command from a microcontroller within the given module. The processor module is configured in the form of a main processor module to which a processor submodule having a greater computational power than the main processor module can be connected via the common data bus, wherein said processor submodule is connected in master mode and the main processor module is switched to slave mode.

Description

Automatic configuration system for modular

PLC

Technology area

The invention relates to programmable logic controllers, hereinafter referred to as PLCs, which are an automated control system operating in accordance with predetermined algorithms. PLC is used to control engineering equipment systems - life support systems of buildings and structures (power supply, water supply, heating, lighting, sewerage, ventilation, etc.), security systems (access control systems, fire extinguishing systems, etc.), transport systems (escalators , elevators, pipeline systems, etc.), systems of service devices, as well as various industrial equipment (machining, thermal, refrigeration, chemical, etc.).

State of the art

A programmable controller is a device consisting of electronic components, active and passive, switching devices, etc., located on printed circuit boards, which process incoming electrical signals and generate output electrical signals. The printed circuit boards of the controller with the components installed on them are placed in a housing that mechanically holds the boards with electronic components in a predetermined position relative to each other and protects them from external influences.

Monoblock PLCs are known, i.e. made in the form of a monoblock, i.e. one building, within which the entire range of PLC functions is performed, which is necessary for organizing the control of an automated object, incl. to interact with the operator and / or the upper-level control system. These functions include mandatory data processing in accordance with a given algorithm, measurement of input signals (analog and / or discrete), supply of control commands to actuators and / or supply of supply voltage to actuators, and, optionally, additional functions may be present - manual entry of threshold values of monitored parameters, interaction with the upper-level control system, performance of the function of a web server, indication of the set states of the controller and / or its inputs / outputs, data display, data transmission and reception, and other functions. Monoblock PLCs can include submodules, which are a printed circuit board enclosed in an individual case or without a case, which is installed directly on the monoblock case and connects to the connectors located on / in the monoblock. Monoblock PLCs have a rigid standard set of analog and discrete inputs and outputs, and are used at such control facilities for which such a set is quite sufficient, for example, in ventilation systems of small buildings and structures. Submodules allow you to optionally change or expand the functionality of the monoblock.

Also, modular PLCs are known, which are a set of functional modules, each of which is made in a separate case, as part of a processor module, the functional purpose of which is to execute algorithms for data processing, and expansion modules that are designed to transform incoming signals into data and / or transforming data into control signals for actuators or influencing actuators, for example, supplying a supply current / voltage. The processor module can have extended functionality, for example, contain ports for connecting to Ethernet / Internet, contain inputs / outputs, perform the functions of a human-machine interface, performed, for example, via a touch screen, or a display in combination with controls, for example, buttons and / or an encoder. Expansion modules, within one housing, can perform both one function, for example, to issue discrete control signals, and several functions, for example, to read input analog / discrete signals and issue control signals / actions.

The interaction of the processor module and expansion modules is carried out through a serial and / or parallel, internal data bus without the need for complex transformations of transmitted signals that require processor processing, for example, as when transferring data via TCP / IP in the Ethernet / Internet network.

The internal data bus of the programmable controller can be implemented both on the basis of standard interfaces, for example, RS-485, 12C, CAN, both individually and in combination, and on the basis of original solutions for organizing the data bus.

The internal data bus has localization - physical limitations of the distance over which data transmission is possible - from one to several meters, depending on the version.

If it is necessary to control expansion modules beyond the localization of the internal data bus, the transmission of control commands and data exchange within the controller between the processor and the functional module is carried out through special interfaces (wired, RS-485 type, wireless) or gateways for data transmission via external networks (wired : Ethernet, CAN, etc.; wireless: Bluetooth, WiFi, GPRS, etc.), which are located, respectively, in the processor module and in expansion modules. Within one modular PLC, one or more types of data buses can be used to transfer data between the processor module and expansion modules, differing in the number of pins and / or data transfer protocols.

The functionality of the processor module or expansion module of a modular PLC can be increased, as well as a monoblock PLC, by installing submodules on / in it.

Modular PLC is used to automate objects where the required number of I / Os ranges from several tens to several thousand. The modular PLC is a flexible device that allows you to configure the I / O and data transmission channels corresponding to the automation object by integrating the processor module and the required number of expansion modules that provide the required number of different inputs / outputs (discrete, analog, power, etc.) , with acceptable redundancy (up to 10 inputs-outputs for a common configuration).

To exchange data between modules in a modular PLC, data buses are used, made in the form of a single device or a dial-up device. The data bus in the form of a single device containing many conductors for transmitting electrical signals and a device for connecting external to PLC modules can be, for example, a multicore cable with connectors for connecting modules or, for example, a printed circuit board, in the form of a strip, with connectors located on it for module connections, electrically connected by printed conductors, or, for example, a printed circuit board, in the form of a strip, with located open printed conductors, against which the electrical contacts of the modules are pressed.

There are solutions that combine the data bus with the processor unit, when the processor unit is implemented in the form of a board, on which there is a printed data bus, which is routed to standard footprints, which are a configuration of pins, incl. acting as contacts installed on the board, on which functional submodules are installed - executive discrete / analog inputs / outputs, power supply, communication ports (interfaces).

The PLC has an internal data bus through which data exchange between the processor and functional modules is provided, and control commands are transmitted from the processor to functional modules.

The PLC interacts with external devices through special devices - hardware interfaces. The hardware interface converts the format of the internal data bus to the format of the external system. Hardware interfaces can be located as part of a processor module, or can be part of a module expansions, or can be allocated into a separate expansion module, and can also be made in the form of a submodule installed on a processor module or an expansion module.

The control architecture inside the modular PLC is based on data exchange via the internal data bus, which transfers control commands from the processor that implements control algorithms to functional blocks and data from functional blocks to the processor or from the processor to functional blocks. Here and hereinafter, functional blocks are understood as complete circuit solutions that implement a specific function as part of a functional module (processor module or expansion module):

> formation of an output signal (discrete or analog);

> detection or measurement of the input signal;

> data exchange with external devices:

• via external networks (Ethernet, CAN, etc.);

• via ports: USB, SD card readers, etc.

> human interaction:

• receiving control actions from the operator (buttons, encoders, jumpers, etc.);

• operator validation (by means of a password, electronic key, reading biometric indicators);

• giving signals to a person (sound and / or light signals, graphic images / text);

• interactive input / output of signals (touchscreen display).

There are specialized modules - operator panels, in which complexes of functional blocks for interaction with a person are implemented on the basis of a graphic display, incl. interactive. Operator panels can be connected to the processor module via a standard interface, for example, Ethernet, RS-232, RS-485, via a proprietary interface, or via the internal data bus used in the PLC.

Operator panels can be made in the form of devices intended to be placed separately from the PLC location (on the DIN rail of the automation cabinet), for example, to be placed on the door of the automation cabinet or on the wall. There are operator panels, which are made in the form of a submodule, which can be installed directly on the processor module or in another place, for example, on the door of the automation cabinet, in which connection is made through a loop.

There are PLCs in which the processor module is combined with the operator panel, this solution is called a panel controller. The panel controller, like the operator panel, can be located on the automation cabinet door or on the wall, as well as on a DIN-rail adapter, which is an expansion module with connector and seat for installing the panel controller. Communication with expansion modules can be carried out via a standard interface (for example, RS-485), or through a wired loop (cable) that connects the spaced-apart internal data buses of the panel controller and the adapter with the expansion modules connected to it.

In the prior art, it is possible for the processor modules to operate in Master and Slave modes. In the Master mode, the processor module executes the algorithm loaded into it, during which it polls the expander modules via the internal data bus, gives them control commands and processes the received data; if there are corresponding functional communication modules, it can be connected to the upper control level (to SCADA system). In the Slave mode, the processor module acts as an expansion module, in which the functional blocks available on the slave processor module become directly accessible for the master processor module for control. The computational resources of the processor module in the Slave mode can be used to execute the algorithms loaded into them, or they can be turned off. If the computational resources are involved, the executable algorithms can directly access the functional blocks located in the housing of the Slave processor module and through the Master processor module to the functional blocks located outside the housing of the Slave processor module.

The disadvantage of these solutions is that when automating the management of a system of objects that has the potential for development in the future, one has to either initially lay in a very high redundancy of computing resources of the processor module or, as the system develops, replace the processor module with a more efficient one, or change the system as a whole if the line of equipment installed at the facility does not contain processor modules with the required performance. All this leads to increased costs for the solution to automate the facility.

The closest analogue of the claimed invention, taken as a prototype, is an expandable controller (see [1] EP0862755, IPC G05B19 / 042, publ. 09.09.1998) containing a processor module connected to a common data bus with the ability to connect to it and to a common data bus at least one expansion module. The disadvantage of the prototype is the inability to increase the processing power.

The essence of the invention

The technical problem facing the invention is to provide the ability to increase the computing resources of a programmable controller without replacing the processor module. The technical result of the claimed invention is to increase the computing resources of the programmable controller without replacing the processor module and corresponding reconnection of the supplied wires.

The problem is solved, and the technical result is achieved due to the system of automatic configuration of a modular PLC, which includes a processor module connected to a common data bus with at least one expansion module connected to it and to a common data bus, while the common data bus is formed by a set of sections of the internal bus, located inside each module and switching devices that provide the transit signal transmission between the modules, while the common data bus includes a service bus for addressing connected devices, a data bus, an alarm transmission line and a "reset" command line, while the service bus is inside Each module contains a redriver that interrupts the data transfer through the service bus on a command from the microcontroller of the same module.

Also, the technical result is achieved due to the fact that the processor module is made in the form of a basic processor module with the ability to connect to it via a common data bus of the processor submodule, the computing resources of which exceed the computing resources of the basic processor module, and the processor submodule is connected in Master mode, and the basic processor the module is switched to Slave mode.

Brief Description of Drawings

FIG. 1 - The main components of the programmable controller.

Error! The link source was not found. - PLC processor module.

FIG. 3 - Block diagram of the PLC.

FIG. 4 - Internal data bus in the configuration of the controller without a processor submodule and the functionality supported by it.

FIG. 5 - Internal data bus in the configuration of the controller with the processor submodule and the functionality supported by it.

FIG. 6 - The flow of tasks processed by the firmware of the base processor module.

FIG. 7 - The flow of tasks processed by the embedded software of the processor submodule.

FIG. 8 - Workflow processed by the add-in firmware.

The following positions are indicated in the figures:

Pos. 1 - Controller processor module; Pos. 2 - Expansion module; Pos.Z - Basic processor module; Pos. 4 - Processor submodule; Pos.5 - Switching socket of the processor module; Pos.6 - Processor module (Structural diagram); Pos. 7 - Processor submodule (structural diagram); Pos. 8 -

Basic processor module (block diagram); Pos. 9 - Switching b device (block diagram); Pos.10 - Expansion module (Structural diagram); Pos.11 - Functional block; Pos.12 - Service bus for addressing modules; Pos.13 - Redriver; Pos. 14 - Microcontroller; Pos.15 - Bus for data transmission; Pos.16 - Line for transmission of alarm signals; Pos.17 - Line for the Reset command for Slave devices; Pos. 18 - Bus for controlling external network devices via a serial interface; Pos.19 - External network devices; Pos.20 - Tasks excluded from the processing flow of the microcontroller when switching from the “Master” mode to the “Slave” mode; Pos.21 - Tasks included in the processing flow of the microcontroller when switching from the “Master” mode to the “Slave” mode.

Implementation of the invention

Description of the device in statics.

The PLC (see Fig. 1) consists of a processor module (1) and expansion modules (2) connected to it, as required for a specific task. The electrical connection of the processor module and expansion modules for transmitting data, control commands and supply voltage is carried out by flexible loops connecting the controller modules in series. The PLC is powered from a secondary power supply located in one of the expansion modules, which is connected to an external voltage source.

The PLC processor module (see Fig. 2) can consist either only of the basic processor module (3), or of the assembly of the basic processor module (3) and the processor submodule (4). The electrical connection of the processor submodule and the basic processor module is carried out through a switching device that provides data transmission, control commands and supply voltage, made either only in the form of a switching connector of the processor module (5), or in the form of a combination (5) and a flexible loop, up to 1 m, installed between the counterparts (5), which are located on the basic processor module (3) and the processor submodule (4).

The block diagram of the PLC (see Fig. 3) shows the block diagram of the processor module (6), its components - the basic processor module (8) and the processor submodule (7), as well as expansion modules (10). All these controller modules contain functional blocks (11) - microcontrollers, analog inputs-outputs based on analog-to-digital and digital-to-analog converters, power switches (solid-state, relays), discrete inputs-outputs, radio communication modules, etc.

The configuration of the functional blocks of the modules can be different (more than 10 thousand configurations), since for each specific control object, the optimal configuration is selected from among those produced, depending on its features. All functional blocks of modules installed in the processor module and in expansion modules have unique addressing within the controller, set by the control algorithm of the automated object, which allows the microcontroller of the basic processor unit or the microprocessor of the processor submodule to access them via the internal data bus, transmit control commands to them and receive data from them.

When the processor unit (1) is configured as only the basic processor unit (3), the placement of the control algorithm is carried out in the basic processor unit.

If the number of inputs-outputs preinstalled on the base processor module is insufficient to control the object to be automated, expansion modules are connected to it. In this configuration, the basic processor module has the status "Master" (master, control), ie. it processes the control algorithm for an automated object (hereinafter referred to as the “control algorithm”) .. Expansion modules have the Slave status (slave, controlled).

If the computing power of the basic processor module is insufficient to control the object to be automated, a processor submodule is installed on it. In this configuration, the processor submodule has the “Master” status (master, control), i.e. it processes the control algorithm of the automated object, the base processor module and expansion modules have the “Slave” status (slave, controlled).

All transmission of data, signals, control commands, as well as the supply voltage inside the controller is carried out through the internal bus. The configuration of the internal bus of the processor module, consisting only of the basic processor module, and the functions supported by it (Fig. 4) differ from the configuration of the internal bus of the processor module, with the submodule installed (see Fig. 5). In the I2C service bus (12), the corresponding data transfer protocol is used to transfer data. The data bus (15) uses the Modbus protocol for data transfer.

Physically, the internal data bus is formed by a set of sections of the internal bus located inside the modules and providing transit signal transmission inside the module and connecting the module to these signal lines, and switching devices (connectors, loops) with the required number of wires / pins. The service bus (12) inside the Slave device has an active element - a red driver (13), which has a direct connection to the microcontroller (14) for transmitting a control signal to the red driver from the microcontroller side. (fourteen). Depending on the control signal supplied from the microcontroller (14) to the red driver (13), the red driver or conducts the signal supplied to it via the bus further, in side from the Master device to other Slave devices connected to the service bus, or blocks this signal.

The basic processor module contains terminals for connecting to the network of external devices connected via the serial CAN or RS485 interface, as well as wires that provide a pass-through signal transmission from the connector to the processor submodule to the specified terminals.

The sequence of the physical location of the Slave devices after the Master device in the PLC is clearly defined by the PLC configuration, which is determined from the specific automation task of the object.

The master device can interact with the Slave devices via two buses: via the service bus (12) and via the data bus (15), respectively, each Slave device has two addresses: to the service bus address and a unique address in the data bus using the Modbus protocol ... The Slave address, both in the service bus and in the data bus, can be either default (initial, the same for all devices, before the address is assigned to it) or unique (assigned by the Master device).

All controller modules have built-in internal software for processing task streams (see Fig. 6, Fig. 7, Fig. 8) of the controller modules. The flows of the processed tasks of the basic processor module in the states "Master" and "Slave" differ:

- tasks excluded from the processing flow when changing the “Master” status to the “Slave” status are displayed in Pos. twenty;

- Tasks included in the processing flow when the “Master” status changes to the “Slave” status are displayed in Pos. 21.

Inside the microcontrollers of the basic processor unit and expansion modules, critical threshold values, which are loaded at startup or when configuring the PLC, can be stored, upon reaching which the microcontroller must issue an alarm signal. The list of critical controlled parameters of an automated facility is limited, selected from among those indicators, the achievement of which can lead an automated facility to an accident in a short time (disrupt its performance and lead to harmful / dangerous consequences). For the critical controlled parameters, the algorithm assigns priorities, in accordance with the degree of their importance for the functioning of the automated facility and the safety of its operation.

The Basic Processor Module also includes a communication submodule with an Ethernet port for connecting the Basic Processor Module to a local network or the global Internet.

Description of the device in action.

To ensure the operability of the PLC, during its commissioning, the control algorithm is loaded into it using the connected to it an external computer with special boot software installed. Loading the download of the control algorithm into the processor module in the presence of a processor submodule is carried out via Ethernet or USB ports of the processor submodule.

In the absence of a processor submodule, the algorithm is loaded into the base processor module through a special download cable connected to an external computer and to the switching connector of the processor module (5) via the data bus (15). Also, the loading of the algorithm into the base processor module can be carried out through the Ethernet port submodule installed on the base processor module.

In the process of loading the control algorithm, a module is specified that will act as a Master device: a basic processor module or a processor submodule. The selected device is assigned the “Master-device” status, which is retained after switching to the operating mode.

When the PLC is turned on, the Master device, on which the algorithm is executed, sends a broadcast message (unaddressed, mandatory for all devices) to the service bus (12) about the configuration reset, as a result of which the default address is returned to all Slave devices (this reset signal is element of the autoconfiguration procedure, which starts automatically when the controller is turned on, however, it is this signal to reset the configuration that makes sense when the system is already configured, all redrivers are in the conduction state, but it needs to be reconfigured, and in the case immediately after turning on all redrivers ) are in a closed state and devices are addressed by default). After the command to reset the configuration, the Master device uses the service bus to access the first slave connected on the bus (for example, N21) using the default address (signal transmission via the service bus to the rest of the Slave devices (for example, N ° Ns 2, 3 After the address of the activated Slave device, a command is sent to assign an address (Modbus address) to the Slave device in the data bus system, then the function blocks of the Slave device are accessed (11) , in accordance with the developed PLC configuration, confirmation of their presence and assignment of addresses to the corresponding inputs / outputs, the next step, assigned Modbus addresses of the Slave device and its inputs / outputs, are assigned to the Slave device and its inputs / outputs (switched, written, etc.) .e. go from the state "as it should be" to the state "as is") .The last action of autoconfiguration of a particular Slave-device is to assign and assign it a unique address in the service bus system, after which a command is sent to the slave device's redriver to transfer it from a closed state to an open one for passing commands through the service bus to other slave devices. After configuring the Slave located the first after the Master device, the second Slave device is configured in a similar way, etc., transfers the common data to the Slave devices to the data bus, identifies them, incl. available in the device and assigns them unique addresses for the duration of the working session (until the next reboot of the system).

The implementation of the main function of the PLC for the implementation of automated control of the object is carried out by periodically evaluating the controlled parameters of the controlled object (receiving feedback from the automated object), in accordance with the control algorithm, and generating control signals for the actuators, which should bring the controlled object to a given state and / or the object must perform a given action (analysis of the situation and the implementation of a control action on the automated object)

The assessment of the monitored parameters of the controlled object is carried out by the Master in three stages: the first stage is sending a request to read data, receiving data and processing the received data.

Assessment of the state of an automated object is carried out by sending requests for data provision, then receiving data on the state of the monitored inputs of the object by determining the signals arriving at the analog and / or discrete inputs of the controller (basic processor unit or expansion modules, see Fig. 3), and / or via the serial interface CAN / RS485 (see pos. 18) and their analysis, in accordance with the algorithm.

Sending a request for data collection is carried out through the data bus (15) and / or through the bus for controlling external network devices (18). Via the data bus (15), the Master device accesses the Slave devices at the addresses assigned via the service bus at the start of the system.

The slave device, after receiving a request for data provision, reads data on the state of the input of interest and transmits it to the Master device via the same data bus (15).

Also, sending a request for data collection is carried out, in accordance with the protocol used, through the control bus of external network devices (18). Through it, in accordance with the same protocol, data is received. Interrogation of the state of the monitored parameters of external network devices (19) is carried out using the data transfer protocol specified by the control algorithm and operating on the basis of the CAN / RS485 interface: CAN, Modbus, ProfiBus DP, LanDrive, etc.

The Master-device processes the received data in accordance with the algorithm, and, depending on the situation, generates control commands to perform corrective actions of the automated object and / or saves the processing results, and / or transfers the received data to the upper level, and / or displays data obtained by means of the configured human-machine interface (indicator lights, display, sound signal).

The formation of corrective actions of the automated object is carried out by sending commands to the Slave devices and their functional blocks to generate output signals (discrete, analog or switching on power currents / voltages) for the actuators of the automated control object connected to the PLC. Slave commands are sent via the data bus (15).

Also, the formation of corrective actions of an automated object is carried out by sending the Master-device commands to external network devices (19) through the control bus of external network devices (18).

The operator's interaction when setting up variable controlled indicators, as well as visual reading information, is carried out by acting on the controls (control buttons, encoder) and receiving feedback through the graphic display. Critical information about the state of the controller and the automated object is also displayed on light indicators.

In the case when the value of at least one critical indicator monitored by the basic processor module and / or expander reaches the threshold value, the corresponding module generates an alarm signal and transmits it to the Master device via a special line for transmitting alarm signals (16). The Master device, having received the alarm signal, in accordance with the priority set by the algorithm, interrogates the Slave devices, accurately diagnoses the situation and performs the actions specified by the algorithm (sends a signal to the SCADA system, stops the equipment, etc.).

If a failure occurs in a separate Slave device, when the device stops responding to requests from the Master device, the Master device sends, via the data bus, for the connected Slave devices a command to ignore the subsequent transmission of the device reset signal via a dedicated signal line (17). Having received a warning command, the Slave devices, in accordance with their internal algorithm, ignore the subsequent reset command of the device received via the dedicated signal line (17). A slave that was in a failed state and was not able to accept the command to ignore the reset command is restarted. After restarting the faulty device, the Slave device returns to a functional state and the address is reassigned via the service bus (12) (without the broadcast command to reset the configuration).

Claims

CLAIM 1. System of automatic configuration of a modular PLC, including a processor module connected to a common data bus with at least one expander connected to it and to a common data bus, while the common data bus is formed by a set of internal bus sections located inside each module and switching devices providing a transit signal transmission between modules, characterized in that the common data bus includes a service bus for addressing connected devices, a data bus, an alarm transmission line and a "reset" command line, while the service bus inside each module contains a redriver , performing the function of interrupting data transmission through the service bus on a command from the microcontroller of the same module. 2. The system according to claim 1, characterized in that the processor module is made in the form of a basic processor module with the ability to connect to it via a common data bus of a processor submodule, the computing resources of which exceed the computing resources of the basic processor module, and the processor submodule is connected in Master mode, and the basic processor module is placed in slave mode.