Control system and programmable logic controller

Abstract

In a control system (1) in which a camera (20) and a PLC (10) are connected via a control network, the camera (20) has a first synchronization counter, the PLC (10) has a second synchronization counter, the control network makes the first and second synchronization counters periodically and repeatedly synchronize with high precision by measuring a transmission delay time a plurality of times between the camera (20) and the PLC (10), the camera (20) attaches a count value of the first synchronization counter at the time of shooting to a shot image and forwards it to the PLC (10) via the control network, and the PLC (10) stores data inside or data of a connected control object, the count value of the first synchronization counter, and image data together with the count value of the second synchronization counter in a storage device inside the PLC (10).

Description

Technical Field

[0001] This invention relates to control systems and programmable logic controllers. Background Technology

[0002] In the field of Factory Automation (FA), logs recorded by PLCs (Programmable Logic Controllers) and images of production equipment captured by cameras are sometimes used to investigate the causes of malfunctions in production equipment. For example, when production equipment performs an abnormal operation, the cause of the abnormal operation is sometimes investigated by comparing the images related to that abnormal operation with the logs attached to the images at the corresponding times. Furthermore, the timestamps attached to the images include, for example, the times when each frame of the image was captured by the camera, and the times when the PLC retrieved the data for each frame of the image.

[0003] Here, if there is a mismatch between the time attached to the image and the time recorded in the log during the cause investigation, it may hinder the cause investigation. Therefore, a technology is needed to match the time attached to the image with the time recorded in the log.

[0004] Patent Document 1 discloses a technique for highly synchronizing the timing of an image capture with the timing of a log recording by connecting a camera (which serves as an image capture device) to a PLC via a dedicated low-latency image capture trigger line. The technique described in Patent Document 1 enables the timing of an image capture to match the timing of a log recording.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-134985 Summary of the Invention

[0006] The technology described in Patent Document 1 requires connecting the camera to the PLC via a dedicated low-latency shooting trigger cable. Therefore, commonly available cameras such as webcams or network cameras cannot be used; a dedicated shooting device corresponding to the shooting trigger cable is required. Furthermore, the need for a dedicated low-latency shooting trigger cable limits remote monitoring.

[0007] The object of the present invention is made in view of the above situation, and its object is to be able to match the time attached to the image with the recording time of the log recorded by the PLC without connecting the camera to the PLC through a dedicated low-latency shooting trigger line.

[0008] To achieve the above objectives, the control system involved in this invention is a control system in which a camera and a programmable logic controller are connected via a control network.

[0009] The camera has a first synchronization counter.

[0010] The programmable logic controller has a second synchronous counter.

[0011] The control network has a mechanism to ensure the longest possible communication delay time by periodically and repeatedly synchronizing the first synchronization counter and the second synchronization counter with high precision by measuring the transmission delay time between the camera and the programmable logic controller multiple times.

[0012] The camera appends the count value of the first synchronization counter at the time of shooting to the captured image and forwards it to the programmable logic controller via the control network.

[0013] The programmable logic controller stores internal data or data of connected controlled objects, the count value of the first synchronization counter, and the captured image together with the count value of the second synchronization counter in the storage device within the programmable logic controller.

[0014] The effects of the invention

[0015] According to the present invention, without connecting the camera to the PLC via a dedicated low-latency shooting trigger line, it is possible to match the time of the image with the recording time of the log recorded by the PLC. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the overall structure of the control system according to an embodiment of the present invention.

[0017] Figure 2 This is a diagram illustrating image mismatch that should be avoided in the control system according to embodiments of the present invention.

[0018] Figure 3 This diagram illustrates a synchronization method based on transmission path delay measurement according to an embodiment of the present invention.

[0019] Figure 4 This is a diagram illustrating the structure of a PLC according to an embodiment of the present invention.

[0020] Figure 5 This is a diagram illustrating the structure of a camera according to an embodiment of the present invention.

[0021] Figure 6 This is a diagram illustrating the structure of an image management device according to an embodiment of the present invention.

[0022] Figure 7 This diagram illustrates the shooting timing according to an embodiment of the present invention.

[0023] Figure 8 The figures illustrate other examples of shooting timing related to embodiments of the present invention.

[0024] Figure 9 This is a diagram showing the sequence of control data in the control network according to an embodiment of the present invention.

[0025] Figure 10 This diagram illustrates how the frequency band for control communication and the frequency band for information communication are divided by time division according to an embodiment of the present invention.

[0026] Figure 11 This diagram illustrates the timing control of the shutter of a camera according to an embodiment of the present invention. Detailed Implementation

[0027] Hereinafter, the control system according to embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same or equivalent parts are labeled with the same reference numerals.

[0028] Figure 1 The control system 1 shown is installed, for example, at a production site where production equipment is located. The control system 1 includes a PLC 10, a camera 20, and an image management device 30. As described later, according to the control system 1, it is possible to match the time accompanying the image of the production equipment captured by the camera 20 with the recording time of the log recorded by the PLC 10.

[0029] An industrial network is constructed to connect PLC 10 with instruments whose actions are controlled by PLC 10 via a control network. In this industrial network, FA instruments requiring real-time control are connected and controlled via Ethernet (registered trademark). As an Ethernet-based industrial network, CC-Link IE Field (registered trademark) and CC-Link IE TSN (registered trademark) are used.

[0030] The PLC 10 and the image management device 30 are communicatively connected via an Ethernet communication cable. Similarly, the PLC 10 and the camera 20 are communicatively connected via an Ethernet communication cable and connected to the control network.

[0031] Camera 20 continuously captures images of the production equipment at constant time intervals. Camera 20 then sends image data representing the continuously captured images of the production equipment to PLC 10. Figure 1 Only one camera 20 is shown, but multiple cameras 20 may exist.

[0032] PLC 10 is a programmable logic controller. In addition to camera 20 and image management device 30, PLC 10 is connected to sensors (not shown), actuators, etc. PLC 10 acquires image data representing images captured by camera 20. As described later, PLC 10 records logs related to its own actions. Furthermore, as described later, PLC 10 saves the acquired image data.

[0033] The video management device 30 reads the logs recorded by PLC 10 and the video data stored by PLC 10, and performs synchronized playback of the logs and videos. Synchronized playback means that when playing a video, the log at the moment of the current playback is displayed along with the video. Through this synchronized playback, for example, a user can observe the synchronized video playback to confirm the state of the production equipment at the moment when abnormal data was recorded in the log. Conversely, if a user discovers an abnormality in the production equipment in the video, they can observe the synchronized video playback log to confirm what data was recorded in the log at the moment the abnormality occurred.

[0034] Next, while referring to Figure 2 On the one hand, it explains the image mismatches that should be avoided in control system 1.

[0035] First, the "Shooting Time" layer will be explained. This layer shows the camera 20 continuously capturing images of the production equipment at constant time intervals. Each vertical line drawn on the "Time" axis represents one captured image, or one frame in the image. Because the vertical lines in the "Shooting Time" layer are arranged at constant intervals, each frame of the image is captured at a constant time interval. After capturing each frame, the camera 20 sends the image data representing each frame to the PLC 10.

[0036] However, while the frames captured by camera 20 are obtained at constant time intervals, jitter can cause them to be received by PLC 10 at inconsistent time intervals. Furthermore, because the clock elements used by camera 20 and PLC 10 differ, a clock difference occurs, sometimes resulting in a discrepancy between the time intervals between frames captured by camera 20 and the time intervals between frames received by PLC 10. Additionally, since camera 20 and PLC 10 are connected via a common communication cable, a delay also occurs when transmitting frames.

[0037] Based on the above, the times when camera 20 captures each frame are usually inconsistent with the times when PLC 10 receives the image data representing each frame. Therefore, even if an attempt is made to associate the images with the log based on the times when PLC 10 receives each frame, the times associated with each frame and the times associated with the log will actually be inconsistent, resulting in a mismatch. The clock difference, jitter, and delay that cause this mismatch will be explained in detail below.

[0038] First, let's explain the clock difference. Figure 2 The "Clock Difference Generation" layer illustrates the frame interval during PLC 10 reception when only a "clock difference" occurs, without "jitter" or "delay." In this layer, the frame interval is constant, but due to the clock difference, it differs from the "Shooting Time" interval. For example, this layer shows a comparison of the time taken for 7 frames during shooting with the time taken for 7 frames during reception; the received 7 frames take longer. Therefore, the timing of reception differs from the timing of shooting, potentially causing mismatches when associating images with logs.

[0039] Next, we will explain the shaking. Figure 2 The "Jitter Occurrence" layer shows the frame interval when PLC 10 receives data without "clock difference" or "delay" and only "jitter". As shown in the "Jitter Occurrence" layer, due to jitter, the frame interval during reception becomes inconsistent and fluctuates. Therefore, the time of reception is inconsistent with the time of capture, which may cause mismatches when associating images with logs.

[0040] Next, we will explain the delay. Figure 2 The "Delay" layer shown illustrates the frame interval when the PLC 10 receives data without incurring "clock difference" or "jitter," only a "delay." In this "Delay" layer, the frame interval is constant and equal to the interval at which the image is captured, but the reception time of each frame is delayed compared to the capture time. This "delay" is caused, for example, by delays due to communication cables or interfaces. Therefore, the reception time is inconsistent with the capture time, potentially causing mismatches when associating images with logs. Furthermore, since the delay is caused by communication cables, interfaces, etc., it can be expected to be approximately constant.

[0041] exist Figure 2 The description covers the case where only one of "clock difference," "jitter," or "delay" occurs in each layer, but typically all three occur. Therefore, it is necessary to eliminate the mismatch corresponding to these three factors.

[0042] PLC 10 is commonly used in mechanical control. Mechanical control based on detection signals from sensors emphasizes responsiveness. These sensors include infrared sensors, magnetic sensors, and even camera systems. In contrast, in machining control, it is often important to synchronize the operation of multi-axis actuators.

[0043] Therefore, in order to ensure synchronization in control networks such as CC-Link IE Field and CC-Link IE TSN, the following mechanism is used: H / W instruments achieve a certain level of timing and statistically measure the transmission path delay to align the timing between instruments with a precision of μ seconds.

[0044] Transmission path delay measurement is a method to achieve higher-precision synchronization by using the measured transmission path delay from the master station to the slave station.

[0045] Figure 3 This illustrates a synchronization method based on transmission path delay measurement. In this method, synchronization occurs at a synchronization point. The transmission control (MyStatus) frames sent from master station 40 experience delays as the distance increases. Master station 40 calculates the transmission delay time for each slave station 50, 60, and 70 based on the master station time at which it receives response signals from each slave station 50, 60, and 70, and sends the calculation to each slave station 50, 60, and 70. The synchronization point is the time elapsed after a certain period (Tsync) from when master station 40 sends the transmission control (MyStatus) frame. Each slave station 50, 60, and 70 synchronizes after subtracting the calculated delay time from the time they received the transmission control (MyStatus) frame, i.e., the Tps time (Tsync - delay time). Thus, slave stations 50, 60, and 70 synchronize at the same time.

[0046] As mentioned earlier, the camera 20 is used as a sensor, and responsiveness is valued, but not as much as synchronous action is valued in a multi-axis actuator.

[0047] Therefore, the shooting behavior of the camera 20 is treated in the same way as the actuator, and synchronous control is performed by applying a control network. A large-capacity memory is added to the PLC 10, which is an embedded control device, and the PLC 10 is used as a data collection device containing images.

[0048] Specifically, in the past, in PLC 10, which only treats control data as an object, the processing of image acquisition was divided into "shooting instruction" and "image forwarding". The synchronization function of the control network was applied to realize the remote connection and storage of image data and control data.

[0049] Next, while referring to Figure 4The structure of PLC 10 will be described below. PLC 10 has a processor 100, a storage device 110, a clock element 120, a synchronous counter 130, and a communication interface 140. The processor 100, storage device 110, clock element 120, synchronous counter 130, and communication interface 140 are communicatively connected to each other via bus B1.

[0050] The processor 100 is, for example, a CPU (Central Processing Unit). The processor 100 performs the functions described later by reading and executing the control program DP stored in the storage device 110.

[0051] Storage device 110 includes, for example, storage devices such as RAM (Random Access Memory), HDD (Hard Disk Drive), and SSD (Solid State Drive). Storage device 110 stores log data (DL), image data (DM), control program (DP), and buffer data (DB). The log data (DL), image data (DM), and buffer data (DB) will be described later. Furthermore, storage device 110 functions as working memory when the processor 100 reads and executes the control program (DP).

[0052] Clock element 120 generates clock signals used when processor 100, storage device 110 and communication interface 140 are in operation.

[0053] Synchronous counter 130 indicates the time by counting the clock signal generated by clock element 120. Synchronous counter 130 is an example of the second synchronous counter of the present invention.

[0054] Communication interface 140 is a communication interface for control networks such as CC-Link IE Field and CC-Link IE TSN. By connecting camera 20 and image management device 30 to communication interface 140, PLC 10 can communicate with camera 20 and image management device 30.

[0055] The functions implemented by the processor 100 by reading and executing the control program DP will be described. The processor 100, by reading and executing the control program DP, includes a log recording unit 101, an image data acquisition unit 102, and an image storage unit 105 as functional units.

[0056] The log recording unit 101 records logs such as sensor data obtained from sensors not shown in the figure and data indicating the internal state of the PLC 10 as log DL in the storage device 110. When recording the log, the log recording unit 101 records the log along with the recording time based on the clock signal emitted by the clock element 120.

[0057] The image data acquisition unit 102 acquires image data representing images captured by the camera 20 and stores it in the storage device 110 as buffer data DB, thereby buffering the image data. At this time, the image data acquisition unit 102 also stores the time of receiving each frame in the buffer data DB. Furthermore, the time of receiving each frame is obtained based on a synchronization counter 130 that counts clock signals emitted by the clock element 120. Here, an upper limit capacity is set for the buffer data DB, and when the data size of the buffer data DB reaches the upper limit capacity, deletion begins from the oldest data. The buffer data DB is implemented, for example, using a circular buffer data structure. The data size of the buffer data DB is, for example, a data size capable of storing 30 minutes of images.

[0058] When a trigger occurs under conditions specified by setting information, the image storage unit 105 extracts image data from the image data contained in the buffer data DB that is near the trigger's occurrence time. For each frame, it stores new image data with the received time appended as image data DM in the storage device 110. Here, "trigger" refers to a signal that instructs the image storage unit 105 to save the image. For example, when a log related to an anomaly in the production equipment is recorded in the log DL, there is a high probability that images from before and after the time the production equipment anomaly occurred are needed, thus triggering the image storage unit 105. Then, the image storage unit 105 saves the image in response to the trigger's occurrence. "Near the trigger's occurrence time" refers, for example, to two minutes before to two minutes after the trigger's occurrence time.

[0059] Camera 20 Figure 5 The device shown includes a processor 200, a storage device 210, a clock element 220, a synchronization counter 230, a communication interface 240, and a camera unit 250. The processor 200, storage device 210, clock element 220, communication interface 240, and camera unit 250 are communicatively connected to each other via bus B2.

[0060] The processor 200 is, for example, a CPU. The processor 200 performs various functions by reading and executing control programs stored in the storage device 210. The storage device 210 includes, for example, storage devices such as RAM and ROM. The imaging unit 250 captures images of the production equipment.

[0061] Clock element 220 generates clock signals used when processor 200, storage device 210, and communication interface 240 operate. Synchronization counter 230 displays the time by counting the clock signals generated by clock element 220. Synchronization counter 230 is an example of the first synchronization counter of the present invention.

[0062] Communication interface 240 is the communication interface for control networks such as CC-Link IE Field and CC-Link IE TSN. By connecting camera 20 and image management device 30 to communication interface 240, camera 20 can communicate with PLC 10. The control network has a mechanism to ensure and compensate for the longest communication delay time from master station to slave station. By measuring the transmission delay time multiple times between camera 20 and PLC 10, the first and second synchronization counters are periodically and repeatedly synchronized with high precision.

[0063] Next, while referring to Figure 6 The structure of the image management device 30 will be described below. The image management device 30 includes a processor 300, a storage device 310, an input device 320, a display device 330, and a communication interface 340. The processor 300, storage device 310, input device 320, display device 330, and communication interface 340 are communicatively connected to each other via bus B3. The image management device 30 is, for example, a personal computer, a smartphone, or other computer.

[0064] The processor 300 is, for example, a CPU. The processor 300 performs various functions by reading and executing control programs stored in the storage device 310.

[0065] Storage device 310 includes, for example, storage devices such as RAM, HDD, and SSD. Storage device 310 stores the control program executed by processor 300. The control program is, for example, a program from an engineering design tool provided by the manufacturer of PLC 10. Furthermore, storage device 310 functions as working memory when the control program is read and executed by processor 300.

[0066] Input device 320 outputs signals based on input operations from the user. Input device 320 may be, for example, a touchscreen integrated with display device 330 described later. Alternatively, input device 320 may also be an input device such as a keyboard or mouse.

[0067] The display device 330 displays information notified to the user based on the control of the display control unit 302. The display device 330 may be, for example, a touchscreen integrated with the input device 320. Alternatively, the display device 330 may be a stand-alone display device.

[0068] The communication interface 340 is a common communication interface such as a USB interface or a network interface. By connecting the PLC 10 to the communication interface 340, the image management device 30 can communicate with the PLC 10.

[0069] The processor 300 performs various functions by reading and executing the control program stored in the storage device 310. The processor 300, as a functional unit, includes a data acquisition unit 301 and a display control unit 302 by reading and executing the control program.

[0070] The data acquisition unit 301 communicates with the PLC 10 via the communication interface 340 to acquire the log DL and image data DM stored in the storage device 110 of the PLC 10.

[0071] Based on user input, the image management device 30 specifies the starting point for playback of the recorded log data and image data, thereby causing the display control unit 302 to display the log data and image data on the display device 330. The following method is conceived as a method for specifying the starting point for playback.

[0072] (1) The starting point of playback is directly specified by inputting the time from the input device 320.

[0073] (2) In the case of a method that records data and images of moments before and after a phenomenon that indicates an anomaly based on log data, the starting point for playback is specified by selecting the phenomenon. For example, for a phenomenon history known as an event history or alarm history, the time and content of the phenomenon (e.g., temperature exceeding limits, speed decrease, etc.) are displayed in a table format, and selection is made. Thus, there is no need for timed matching of images and data, avoiding tedious operations.

[0074] Regarding the collection of image data synchronized with control data that utilizes the synchronization function of the control network, the following three points will be explained.

[0075] (a) Control method for shooting timing

[0076] (b) Method for forwarding captured data

[0077] (c) Method for determining the shooting time

[0078] (a) Control method for shooting timing

[0079] The shooting behavior of the camera 20, which appears to be a sensor, is treated as an actuator. The synchronization function of the control network is used for synchronous control, thereby synchronizing the timing with respect to other control data. The PLC 10 uses this synchronization function to control the shooting timing that instructs the camera 20 to take pictures.

[0080] Figure 7 It is against the general Figure 3 The diagram illustrates the timing of image capture when slave station 70 is configured as camera 20. Master station 40 is PLC 10. (Example:) Figure 7As shown, the cycle of implementing the entire sequence is constant, constituting one loop called a link scan. Imagine PLC 10 scanning along this link to transmit the capture timing to camera 20. However, as explained earlier, this results in a delay that depends on the transmission path; depending on the network location, the delay time is not uniform, making interfacing with control data difficult.

[0081] Therefore, by applying the synchronization function as is, the camera 20 automatically determines the shooting timing along the synchronization points of the network, according to the setting information indicated by the PLC 10 or the pre-set information with timing at every specified number of synchronization points. For synchronization points, the PLC 10 manages the deviation time, enabling high-precision integration of shooting timing and control data. However, in this case, shooting instructions with a precision exceeding that of synchronization points are not possible.

[0082] Figure 8 Further examples are shown. Based on the counter information representing the synchronization point, i.e., the time after synchronization, the camera 20 automatically determines the shooting timing according to the setting information obtained from the PLC 10 or the preset setting information. As a specific example, there is a shooting reservation based on an arbitrary synchronization counter value that is more likely to occur in the future than the communication delay guaranteed by the network. When the PLC 10 operates with a cycle determined by the function that keeps the scan time constant, i.e., constant scan, it is also possible to make repeated shooting reservations with a starting synchronization counter value that is more likely to occur in the future than the communication delay and a repeating counter cycle. Alternatively, shooting reservations can be made simply with a fixed counter cycle, such as 60Hz, and the camera 20 operates at an arbitrary timing.

[0083] (b) Method for forwarding captured data

[0084] The characteristic of a control network is that, in order to ensure the timing of control, such as... Figure 9 As shown, the same small amount of data is repeatedly sent and received at high speed. In contrast, in the forwarding of image data, compression is performed to ensure bandwidth. Therefore, the capacity of the image data corresponding to a frame is not constant. In particular, the keyframe size is larger than the differential frame, making it impossible to apply synchronization as is in the control network. Consequently, image data differs from previous control data and is difficult to send in a single cycle. If the communication cycle is determined by matching the maximum size of the keyframe, the cycle becomes slow and cannot be applied to mechanical control.

[0085] CC-Link IE Field, CC-Link IE TSN and other control networks such as Figure 10The control communication band and the information communication band are divided by time segmentation. Therefore, the information communication band is used as the band for forwarding image data. By using the information communication band, image forwarding can be performed without affecting control. However, since the band is divided, it is preferable to compress the video to avoid putting pressure on the band. The control communication band is used to transmit synchronization timing data.

[0086] Alternatively, the control network can be used for only timing and synchronization of the shooting, as well as the transmission and reception of time information, while image forwarding uses other communication lines. However, due to the separate communication lines, it is not convenient for users in terms of the dual setup of communication lines and different deployment methods.

[0087] (c) Method for determining the shooting time

[0088] As a method for determining the shooting time of camera 20, there are two methods: one is determined by PLC 10, and the other is determined by image data added by camera 20.

[0089] As a method for determination by PLC 10, the delay can be predicted and added by PLC 10, or it can be added by instructing PLC 10 to send and receive identification information at the time of shooting. At synchronization points along the network, if the camera 20 automatically determines the shooting timing according to setting information indicated by PLC 10 or pre-set information with timing at every specified number of synchronization points, the time of the next synchronization point can also be added by PLC 10.

[0090] As a method for the camera 20 to append the shooting time to the image data, for example, the actual time in UNIX (trademarked) time based on nanoseconds can be appended to each frame of the image. Alternatively, a frame count value with an operating frequency of 90 kHz from the camera 20's clock counter can be appended, matching the video format specifications. In the case of appending a 90 kHz frame count value, the time when the counter reaches 0 is shared beforehand between the camera 20 and the PLC 10. This method of appending the counter information, representing the time after synchronization (a calculation source indicating a synchronization point), to the image data and forwarding it according to the setting information obtained from the PLC 10 or a pre-set setting, is simple and reliable.

[0091] Figure 11This diagram illustrates the timing control of the shutter of camera 20. As a method for controlling the shooting timing, when the camera 20 automatically determines the shooting timing based on counter information indicating the time after synchronization (a calculation source representing the synchronization point), or according to setting information obtained from PLC 10 or pre-set information, the camera 20 can perform advance shooting control within a grace period as needed by making a shooting reservation with an arbitrary synchronization counter value that is further in the future than the communication delay. Matching with the center of the exposure time range is effective when considering the interface with control data. Mechanical speeds are often faster than shutter speeds, sometimes making image blur unavoidable. By setting the blur center as a reference for shooting, the correlation between control data and phenomena can be analyzed more accurately.

[0092] With multiple cameras 20 configured, the shooting timing between the cameras 20 can be matched with high precision. Therefore, it is possible to achieve precise docking of image data between the cameras 20 and synthesize images from multiple cameras 20. For example, by configuring multiple cameras 20 and distorting and synthesizing them into a 360-degree image, natural, blind-angle-free images can be saved, reducing the workload of fault analysis.

[0093] In the above embodiments, the image management device 30 has an input device 320 and a display device 330, but the input device 320 and the display device 330 may also be external devices.

[0094] (Other variations)

[0095] The program used in the PLC 10 or image management device 30 can be stored and distributed on computer-readable recording media such as CD-ROM (Compact Disc Read Only Memory), DVD (Digital Versatile Disc), USB flash drive, memory card, and HDD. Furthermore, by installing the aforementioned program into a programmable logic controller (PLC) or a general-purpose computer, the PLC or general-purpose computer can function as the PLC 10 or image management device 30.

[0096] Alternatively, the program can be pre-stored on the storage device of another server on the Internet, and then downloaded from that server.

[0097] This invention allows for various implementations and modifications without departing from its broad spirit and scope. Furthermore, the above-described embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. That is, the scope of the invention is defined by the claims, not the embodiments. Moreover, various modifications implemented within the scope of the claims and their equivalents are considered to fall within the scope of this invention.

[0098] Explanation of the label

[0099] 1. Control system, 10. PLC, 20. Camera, 30. Image management device, 40. Master station, 50, 60, 70. Slave stations, 100. Processor, 101. Log recording unit, 102. Image data acquisition unit, 105. Image storage unit, 106. Display control unit, 110. Storage device, 120. Clock element, 130. Synchronization counter, 140. Communication interface, 200. Processor, 210. Storage device, 220. Clock element, 230. Synchronization counter, 240. Communication interface, 250. Imaging unit, 300. Processor, 301. Data acquisition unit, 302. Display control unit, 310. Storage device, 320. Input device, 330. Display device, 340. Communication interface, B1, B2, B3 bus, DB buffer data, DL log, DM image data, DP control program.

Claims

1. A control system in which a camera and a programmable logic controller are connected via a control network. in, The camera has a first synchronization counter. The programmable logic controller has a second synchronous counter. The control network periodically synchronizes the first synchronization counter and the second synchronization counter by measuring the transmission delay time between the camera and the programmable logic controller multiple times. The camera appends the count value of the first synchronization counter at the time of shooting to the captured image and forwards it to the programmable logic controller via the control network. The programmable logic controller (PLC) stores its internal data or data of the connected controlled object, the count value of the first synchronization counter, and the captured image along with the count value of the second synchronization counter in its internal storage device. The programmable logic controller uses the synchronization function of the control network to synchronously control the shooting behavior of the camera.

2. The control system according to claim 1, wherein, The programmable logic controller instructs the camera to schedule a shooting session based on the count value of the second synchronization counter, which is greater than or equal to the longest communication delay time of the control network. The camera takes pictures at a timed interval corresponding to the count value of the first synchronization counter, which is the same as the count value of the second synchronization counter.

3. The control system according to claim 2, wherein, The camera shutter is opened at a time when the shooting time scheduled for the shooting coincides with the center of the camera's exposure time range.

4. The control system according to claim 1, wherein, The camera converts the count value of the first synchronization counter into a frame count value at a different frequency than the first synchronization counter, and sends the image data and the frame count value together to the programmable logic controller.

5. The control system according to claim 1, wherein, If a trigger occurs under a condition specified by the setting information, the programmable logic controller stores the image data and the control data for the period before and after the trigger of the condition specified by the setting information in the storage device within the programmable logic controller.

6. The control system according to claim 2, wherein, The camera is multiple cameras. The programmable logic controller instructs the plurality of cameras to schedule a shooting session based on the count value of the second synchronization counter, which is greater than or equal to the longest communication delay time of the control network. The data of the captured images received from the multiple cameras are combined and stored in the storage device.

7. The control system according to claim 2, wherein, The programmable logic controller has the function of keeping the scan time constant. The camera is instructed to schedule a shooting appointment based on the count value of the second synchronization counter, which is greater than or equal to the longest communication delay time of the control network, and is more likely to be scanned by the programmable logic controller in the future.

8. A programmable logic controller connected via a control network to a camera having a first synchronization counter. in, It has a second synchronous counter and a storage device. The system receives captured images with the count value of the first synchronization counter attached, wherein the first synchronization counter is periodically and repeatedly synchronized with the camera by measuring the transmission delay time between the control network and the camera. The internal data or data of the connected controlled object, the count value of the first synchronization counter, and the captured image are stored together with the count value of the second synchronization counter in the storage device. The second synchronization counter is periodically synchronized with the camera by measuring the transmission delay time between the control network and the camera. The programmable logic controller uses the synchronization function of the control network to synchronously control the shooting behavior of the camera.

Images