WO2025127173A1 - Apparatus and method for plc time synchronization for communication control of smart factory system - Google Patents

Abstract

The present invention relates to an apparatus and a method for PLC time synchronization for communication control of a smart factory system, the apparatus comprising: a plurality of PLCs; a traffic generator for providing control traffic to each of the plurality of PLCs; and a time-sensitive networking device for synchronizing the time of the PLCs and the traffic generator and scheduling a traffic transmission time.

Description

PLC time synchronization device and method for communication control of smart factory system

The present invention relates to a PLC time synchronization device and method for communication control of a smart factory system, and more specifically, to a PLC time synchronization device and method based on the Precision Time Protocol (PTP).

The present invention was filed as a result of performing the following tasks.

[Task ID] 1711152811

[Subject Number] 2020-0-00647-003

[Ministry Name] Ministry of Science and ICT

[Research Management Specialist Agency] Information and Communication Planning and Evaluation Institute

[Research Project Name] Development of 5G-based IoT core technology

[Research Project Name] Development of On-Device High-Speed Event Complex Analysis and Synchronization Technology for IoT Time Series Data Applicable to Smart Factory Field

[Contribution rate] 1/1

[Organization] Korea Electronics Technology Institute

[Research Period] 2023-01-01 ~ 2023-12-31

In general, it receives signals from PLC equipment, processes them according to the programming content inside the PLC, and then outputs the processed signals to the equipment. In other words, smooth operation of the PLC means that the automation equipment inside the factory is operating efficiently. Therefore, continuous monitoring of the operation of the PLC is necessary.

Since PLCs are mainly controlled unmanned, when abnormal operation is discovered, a series of operations can be monitored to take follow-up measures or log data such as past history can be saved to confirm how the abnormal operation occurred.

The PLC's data log module has a configuration in which the values of related equipment (devices) are saved as log data along with time when the conditions set by the user are satisfied, and the saved log data is stored in external memory.

In order to provide multiple PLC data to a monitoring device, an Ethernet switch was previously placed between multiple PLCs and the monitoring device.

Figure 1 is an example of a connection between a PLC and a monitoring device in a conventional smart factory.

Referring to FIG. 1, a conventional smart factory can be configured to connect a plurality of PLCs (10) and a traffic generator (20) to one Ethernet switch (30) and communicate with a monitoring device (40) to provide data.

At this time, the Ethernet switch (30) does not have time synchronization and scheduling functions, and simply serves to connect communication lines to enable communication between devices.

A plurality of PLCs (10) each transmit collected data to a monitoring device (40), and a traffic generator (20) can generate traffic for controlling the PLCs (10) or for checking the quality of the network.

Data from the traffic generator (20) can be provided to each PLC (10).

An Ethernet-based network of this type is a type of local area network (LAN) and is the most widely used network type.

However, standard Ethernet has the problem that it does not guarantee real-time performance and determinism.

Therefore, when traffic increases, communication delays and communication disconnections may occur.

However, conventional methods have the limitation that there is no way to resolve communication delays or disconnections that occur for any reason.

This is because standard Ethernet does not define a solution to address communication disconnections due to increased traffic.

In general Internet communication, even if there is a slight delay, you only have to tolerate a brief buffering period.

However, smart factories include manufacturing facilities and control systems that handle hazardous materials, so even a minor communication delay can reduce overall productivity and lead to major accidents.

Especially in mission-critical industries such as energy, where systems may stop due to communication outages, more sophisticated communication processing and system synchronization are required.

The problem that the present invention seeks to solve in consideration of the problems of the prior art as described above is to provide a PLC time synchronization device and method for communication control of a smart factory system that can prevent communication from being delayed or disconnected even when traffic increases.

In order to solve the above technical problem, a time synchronization device of a PLC according to one aspect of the present invention includes a plurality of PLCs, a traffic generator providing control traffic to each of the plurality of PLCs, and a time-sensitive networking device synchronizing the time of the PLCs and the traffic generator and scheduling a traffic transmission time.

In an embodiment of the present invention, the time-sensitive networking device may further include a monitoring device that is connected to the time-sensitive networking device and monitors PLC data.

In an embodiment of the present invention, time synchronization can be achieved by the general Precision Time Protocol (gPTP).

In an embodiment of the present invention, the time-sensitive networking device can control the opening and closing of the gate according to the scheduled traffic transmission time.

In addition, a method for synchronizing time of a PLC according to another aspect of the present invention is a method performed in a time-sensitive networking device that forms a time-sensitive network with a plurality of PLCs and traffic generators, the method including: a) a step of synchronizing time of the PLCs and the traffic generator; and b) a step of scheduling a control traffic transmission time of the traffic generator.

In an embodiment of the present invention, a monitoring device is included for monitoring the PLC data through the time-sensitive network device, and step a) can synchronize the time of the monitoring device together.

In an embodiment of the present invention, time synchronization can be achieved by the general Precision Time Protocol (gPTP).

Figure 1 is an example diagram of a conventional PLC network configuration.

Figure 2 is an example diagram of a PLC network configuration of the present invention.

Figure 3 is an example diagram showing a time synchronization process using gPTP.

Figure 4 is an example of scheduling for transmitting control traffic of a traffic generator (2) to a PLC (1).

- Explanation of symbols -

1:PLC 2:Traffic Generator

3: Time sensitive networking devices 4: Monitoring devices

In order to fully understand the configuration and effect of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and can have various changes. However, the description of the embodiments is provided so that the disclosure of the present invention is complete, and so that a person having ordinary knowledge in the technical field to which the present invention belongs is fully informed of the scope of the invention. In the accompanying drawings, the components are illustrated with their actual sizes enlarged for convenience of explanation, and the ratio of each component may be exaggerated or reduced.

The terms "first", "second", etc. may be used to describe various components, but the components should not be limited by the terms. The terms may only be used to distinguish one component from another. For example, without departing from the scope of the present invention, the "first component" may be referred to as the "second component," and similarly, the "second component" may also be referred to as the "first component." In addition, singular expressions include plural expressions unless the context clearly indicates otherwise. The terms used in the embodiments of the present invention may be interpreted as having a meaning commonly known to a person of ordinary skill in the art, unless otherwise defined.

Hereinafter, a time synchronization device and method of a PLC for communication control of a smart factory system according to an embodiment of the present invention will be specifically described with reference to the drawings.

FIG. 2 is a block diagram of a time synchronization device of a PLC for communication control of a smart factory system according to a preferred embodiment of the present invention.

Referring to FIG. 2, the present invention can be configured to form a time-sensitive network by connecting a plurality of PLCs (1) and a traffic generator (2) to a single time-sensitive networking device (3), and provide data to a monitoring device (4) connected to the time-sensitive network.

Time Sensitive Networking (TSN) is a set of standards for implementing deterministic message delivery in standard Ethernet networks. Deterministic here means that the transmission and reception of network information is unconditionally completed without exception, and in TSN, this must be done within a target time.

A plurality of the above PLCs (1) and time-sensitive networking devices (3) use the general Precision Time Protocol (gPTP) to provide integrated settings for time synchronization, scheduling of data traffic, and TSN compatibility.

Figure 3 is an example diagram showing a time synchronization process using gPTP.

Referring to Fig. 3, more accurate time synchronization can be achieved between a PLC (1) and a time-sensitive networking device (3) through a request for delay time information (Pdelay Request), a response thereto (Pdelay Response), and a follow-up of the response (Pdelay Response Follow Up).

In this state where time synchronization is achieved, the time-sensitive networking device (3) schedules the data traffic of each PLC (1) and traffic generator (2).

The PLC (1) and traffic generator (2) transmit data according to a set schedule after time synchronization, and the time-sensitive networking device (3) controls the communication gate according to the schedule to provide data from each PLC (1) to the monitoring device (4), or provide PLC control traffic of the traffic generator (2) to each PLC (1).

Figure 4 is an example of scheduling for transmitting control traffic of a traffic generator (2) to a PLC (1).

Referring to Fig. 4, in order to transmit control traffic to PLC (1), a cycle of 1000 ms is set, and the gate is opened for 100 ms from the start of the cycle so that control traffic from the traffic generator (2) can be transmitted to PLC (1).

In this way, by synchronizing the time of each PLC (1) and traffic generator (2) and scheduling the traffic transmission time, traffic transmission can be guaranteed and data link disconnection can be prevented.

Therefore, the present invention can prevent a decline in productivity due to communication delay and disconnection in a smart factory and reduce the risk of accidents.

Although the embodiments according to the present invention have been described above, they are merely exemplary, and those with ordinary skill in the art will understand that various modifications and equivalent embodiments are possible from this. Accordingly, the true technical protection scope of the present invention should be determined by the following claims.

The present invention relates to a device and method for synchronizing the time of a PLC in a smart factory using natural laws, and has industrial applicability.

Claims (7)

Multiple PLCs; A traffic generator that provides control traffic to each of a number of PLCs; A device comprising a time-sensitive networking device for synchronizing the time of the PLC and the traffic generator and scheduling the traffic transmission time. In the first paragraph, A device further comprising a monitoring device connected to said time sensitive networking device for monitoring PLC data. In the first paragraph, Time synchronization is, A device characterized by being implemented by the general Precision Time Protocol (gPTP). In the first paragraph, The above time sensitive networking device, A device characterized by controlling the opening and closing of a gate in accordance with a scheduled traffic transmission time. A method performed on a time-sensitive networking device comprising a plurality of PLCs and traffic generators and a time-sensitive network, comprising: a) a step of synchronizing the time of the PLC and the traffic generator; and b) A method comprising the step of scheduling a control traffic transmission time of the traffic generator. In paragraph 5, Including a monitoring device for monitoring the PLC data through the time sensitive network device; A method characterized in that the step a) above synchronizes the time of the monitoring device together. In paragraph 5, Time synchronization is, A method characterized by being performed by the general Precision Time Protocol (gPTP).

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