Optical wireless communication fieldbus, industrial equipment, and method for adjusting light intensity
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- CHUO DENSHI
- Filing Date
- 2025-03-14
- Publication Date
- 2026-08-03
Smart Images
Figure 0007898768000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an optical wireless communication fieldbus used for communication between peripheral devices and control devices arranged in a housing of industrial equipment, an industrial equipment provided with the optical wireless communication fieldbus, and a method for adjusting the emission intensity of the optical wireless communication fieldbus.
Background Art
[0002] As a connection method for connecting a plurality of devices in industrial equipment, specifically, for communicating control data between a control device and a plurality of slave devices, connection by a fieldbus may be performed, prioritizing high real-time communication and short response time (for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, regarding industrial equipment, a large number of devices including a control device and a plurality of slave devices are arranged in a housing having longitudinal and lateral dimensions of about 1 m to 2 m, and the fieldbus used for connecting these large number of devices is generally connected by wire. FIG. 1 is an explanatory diagram showing a conventional technique in which a control device and a plurality of slave devices arranged in a housing of industrial equipment are connected by a wired fieldbus. In FIG. 1, it can be seen that signal line cables are arranged so as to pass through the gaps between the devices. On the other hand, in recent years, the number of devices installed in one housing has been increasing, and there has been a problem that the labor and cost of wiring are incurred during installation and maintenance.
[0005] To address this, one might consider wirelessly connecting fieldbuses used for connecting multiple devices in industrial equipment. While the use of wireless LANs or wireless PANs comes to mind for wireless fieldbuses, practical considerations include difficulties in ensuring communication quality due to radio interference with other 2.4GHz band communications such as Wi-Fi® and Bluetooth®, as well as risks of communication interception and spoofing. In this regard, using optical wireless communication, which is unaffected by interference from other radio wave communications, is a possibility. However, since many slave devices located inside the enclosure are battery-powered, such as various sensors, there are issues with power consumption and other practical challenges.
[0006] The present invention has been made in view of the above, and aims to provide an optical wireless communication fieldbus that is not subject to interference from other radio wave communications and is also highly practical. [Means for solving the problem]
[0007] To achieve this objective, the present invention provides a fieldbus used for communication between peripheral and control devices arranged within the housing of industrial equipment, wherein the fieldbus consists of an optical wireless master and a plurality of optical wireless slaves that transmit and receive signals by optical wireless communication, the optical wireless master comprises a plurality of light-emitting elements and at least one light-receiving element, and at least the light emission intensity of the optical wireless slaves is individually adjusted according to the individual installation conditions of the plurality of optical wireless slaves. Each optical wireless slave is mounted at an arbitrary position without a predetermined placement location. The placement location of each optical wireless slave is determined by a binary search method by selectively emitting all or part of the multiple light-emitting elements of the optical wireless master. Furthermore, when an optical wireless slave receives a light intensity adjustment command from a predetermined light-emitting element of the optical wireless master, it repeatedly performs the process of gradually increasing the light intensity from the lowest level and transmitting a response signal to the optical wireless master. The light intensity at which a reply signal from the optical wireless master is received in response to the response signal is determined as the adjusted light intensity. This is an optical wireless communication fieldbus characterized by the presence of [something]. Here, "optical wireless communication" includes not only infrared communication, which is a typical example of optical wireless communication, but also visible light communication and ultraviolet communication.
[0008] Furthermore, in order to achieve the above objective, the present invention provides a fieldbus used for communication between peripheral devices and control devices arranged in a housing, wherein the fieldbus consists of an optical wireless master that transmits and receives signals by optical wireless communication and a plurality of optical wireless slaves, the optical wireless master is equipped with a plurality of light-emitting elements and at least one light-receiving element, and at least the light emission intensity of the optical wireless slaves is individually adjusted according to the individual installation conditions of the plurality of optical wireless slaves. Each optical wireless slave is mounted at an arbitrary position without a predetermined placement location. The placement location of each optical wireless slave is determined by a binary search method by selectively emitting all or part of the multiple light-emitting elements of the optical wireless master. Furthermore, when an optical wireless slave receives a light intensity adjustment command from a predetermined light-emitting element of the optical wireless master, it repeatedly performs the process of gradually increasing the light intensity from the lowest level and transmitting a response signal to the optical wireless master. The light intensity at which a reply signal from the optical wireless master is received in response to the response signal is determined as the adjusted light intensity. This industrial device is characterized by having an optical wireless communication fieldbus, through which communication between peripheral devices and control devices is performed.
[0009] Furthermore, in order to achieve the above objective, the present invention provides a method for adjusting the light emission intensity between an optical wireless master and an optical wireless slave in an optical wireless communication fieldbus used for communication between peripheral devices and control devices arranged in the housing of industrial equipment, comprising at least the steps of: the optical wireless slave receiving a light emission intensity adjustment command from the optical wireless master; the optical wireless slave transmitting a response signal to the optical wireless master at the lowest level of light emission intensity; the optical wireless slave confirming whether or not it has received a reply signal from the optical wireless master in response to the response signal; and, if the reception of the reply signal is not confirmed in the slave-side confirmation step, the optical wireless slave re-transmitting a response signal to the optical wireless master at a light emission intensity one level higher, and if the reception of the reply signal is confirmed, determining the adjusted light emission intensity of the optical wireless slave, wherein the steps from the slave-side confirmation step to the slave-side adjustment step are repeatedly performed as necessary. The process includes at least the following steps: the optical wireless master sends a light intensity adjustment command at the maximum level of light intensity, and then receives a reception acknowledgment response signal from the optical wireless slave; the optical wireless master sends a presence acknowledgment signal to the optical wireless slave at the lowest level of light intensity; a master-side confirmation step confirms whether the optical wireless master has received a response signal from the optical wireless slave to the presence acknowledgment signal; and if the reception of the response signal is not confirmed in the master-side confirmation step, the optical wireless master sends another presence acknowledgment signal to the optical wireless slave at a light intensity one level higher, and if the reception of the response signal is confirmed, a master-side adjustment step determines the adjusted light intensity of the optical wireless master, and if necessary, the steps from the master-side confirmation step to the master-side adjustment step are repeatedly executed. This is a method for adjusting the luminescence intensity characterized by the following: [Brief explanation of the drawing]
[0010] [Figure 1] This is an explanatory diagram illustrating conventional technology in which a control device located within the enclosure of industrial equipment is connected to multiple slave devices via a wired fieldbus. [Figure 2]This is a simplified explanatory diagram showing an example of a communication environment performed by an optical wireless master and a plurality of optical wireless slaves in an optical wireless communication fieldbus according to an embodiment of the present invention, where Figure 2(a) is a rear view and Figure 2(b) is a side view. [Figure 3] This is an explanatory diagram showing an example of a light emission intensity adjustment function realized by an optical wireless communication fieldbus according to an embodiment of the present invention, and illustrating the first stage thereof. [Figure 4] This is an explanatory diagram showing an example of a light emission intensity adjustment function realized by an optical wireless communication fieldbus according to an embodiment of the present invention, and illustrating the second stage thereof. [Figure 5] This is an explanatory diagram showing an example of a light emission intensity adjustment function realized by an optical wireless communication fieldbus according to an embodiment of the present invention, and illustrating the third stage thereof. [Figure 6] This flowchart shows some of the processes performed on a master in an optical wireless communication fieldbus according to an embodiment of the present invention, and is a flowchart of the processes performed to confirm the existence of a slave. [Figure 7] This is a flowchart showing some of the processing performed on a master in an optical wireless communication fieldbus according to an embodiment of the present invention, the flowchart showing the processing performed for searching for an LED to emit light, and the diagram showing the first iteration of the loop processing. [Figure 8] This is a flowchart showing some of the processing performed on the master in an optical wireless communication fieldbus according to an embodiment of the present invention, the flowchart showing the processing performed for searching for an LED to emit light, and the second iteration of the loop processing. [Figure 9] This is a flowchart showing some of the processes performed on the master in an optical wireless communication fieldbus according to an embodiment of the present invention, the flowchart showing the processes performed for adjusting the light emission intensity, and the diagram showing the first iteration of the loop process. [Figure 10]This is a flowchart showing some of the processes performed on the master in an optical wireless communication fieldbus according to an embodiment of the present invention, the flowchart showing the processes performed for adjusting the light emission intensity, and the second iteration of the loop processing. [Figure 11] This flowchart shows the processing performed on a slave in an optical wireless communication fieldbus according to an embodiment of the present invention. [Modes for carrying out the invention]
[0011] [Embodiments of the present invention] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the drawings are created for illustrative purposes and may intentionally omit components that are not necessary for the explanation in order to make them easier to understand. Also, components may be intentionally enlarged or reduced in size for illustrative purposes and are not drawings that show an accurate scale. In the following explanation, the same reference numerals in different figures indicate parts with the same function, and redundant explanations in each figure will be omitted as appropriate.
[0012] <Overall Fieldbus Configuration> Figure 2 is a simplified explanatory diagram showing an example of a communication environment performed by an optical wireless master and a plurality of optical wireless slaves in an optical wireless communication fieldbus according to an embodiment of the present invention, where Figure 2(a) is a rear view and Figure 2(b) is a side view. Hereafter, embodiments of the present invention will be described using infrared communication, but visible light communication or ultraviolet communication may also be used, and any method of optical wireless communication can be adopted.
[0013] Inside the housing 3, as shown in FIGS. 2(a) and 2(b), a partition plate 4 is provided to separate the space for infrared communication by the communication device from the space where the control device and the like are arranged, so that a good communication environment is achieved. That is, on the front side across the partition plate 4, the upper device 11 such as the control device and the slave device 21 such as the sensor are arranged, while on the back side across the partition plate 4, as shown in FIG. 2(a), the infrared master 1 and the plurality of infrared slaves 2 are arranged. The plurality of infrared slaves 2 are set with addresses of ID1, ID2, and ID3. In the example shown here, the infrared slaves 2 with the addresses of ID1 to ID3 are arranged neatly at substantially equal intervals in order of their numbers, but this is a simplified example for explanation purposes only. In fact, the infrared slaves 2 arranged in the housing 3 often exist disorderly regardless of the positional relationship and the order of the address numbers. However, if there is room for the number and density of the devices arranged inside, it may be possible to have an orderly arrangement as in the example shown in FIG. 2(a).
[0014] In Figure 2(a), while the infrared slave 2 is composed of multiple units, the infrared master 1 itself is a single unit, but the infrared master 1 is equipped with multiple light-emitting elements and one light-receiving element (see Figure 3). However, this is merely one example, and due to the layout of the enclosure or for redundancy, it is possible to have multiple higher-level devices when multiple systems of higher-level and lower-level devices are provided, or when multiple higher-level and lower-level relationships are connected in a multi-stage series connection, in which case multiple infrared masters will also be installed. Specifically, in situations where it is difficult for a single master to cover the communication path, such as in a confined space within the enclosure, a multi-master configuration can be used. In such a multi-master configuration, it is advisable to synchronize the masters to prevent overlapping transmission timings between them. Furthermore, for redundancy, it is possible to install an active master and a standby master. In this configuration, under normal circumstances, the active master communicates with the slaves. If the active master fails or stops, the higher-level device detects the failure and instructs the standby master to begin communication. The standby master then communicates with the slaves from that point onward.
[0015] While the host device 11 is powered by a commercial power supply, some of the slave devices 21, particularly small sensors, may be powered by batteries. Therefore, reducing power consumption due to infrared communication is important. Incidentally, when connecting a general-purpose PC and wireless peripherals using infrared communication, it is common practice to set the light intensity to nearly maximum for communication. This is because the relative positions of general-purpose PCs and peripherals change each time they are used, and naturally, the relative positions of the master and slave in infrared communication also change each time. Furthermore, in some cases, a stable relative position may be disrupted during communication. Therefore, sufficient light intensity is essential to ensure effective communication. On the other hand, for industrial equipment targeted by the present invention, once installed, the positional relationship between the master and slave generally does not change. Nevertheless, communication may be performed with a light emission intensity that is unnecessarily high, potentially consuming power wastefully. For example, compared to the slaves of ID1 and ID3 shown in Fig. 2(a), the slave of ID2 is in a more directly facing posture with respect to the master, and it should be possible to establish communication even with a weak light emission intensity. However, if the light emission intensities of the three slaves are made uniform, power consumption will be wasted in the slave of ID2. Regarding this, the infrared communication field bus according to an embodiment of the present invention is used with the light emission intensity individually adjusted according to the individual installation status of a plurality of infrared slaves, so that power consumption can be suppressed. Hereinafter, this adjustment method will be described.
[0016] <Overview of Light Emission Intensity Adjustment><{0000100}>First, the overview of the light emission intensity adjustment function realized by the infrared communication (optical wireless communication) field bus according to an embodiment of the present invention will be described using the explanatory diagrams of Figs. 3 to 5. Fig. 3 shows the first stage of light emission intensity adjustment, Fig. 4 shows the second stage of light emission intensity adjustment, and Fig. 5 shows the third stage of light emission intensity adjustment, respectively.
[0017] The first step is to check whether an infrared slave corresponding to the address exists. As mentioned earlier, multiple slave devices are arranged haphazardly within the industrial equipment enclosure, regardless of their relative positions or address number order. Furthermore, since the addresses are absolute rather than relative, it is possible that slave devices corresponding to ID1 and ID3 exist, but a slave device corresponding to ID2 does not. For this reason, a process to check for the existence of a slave is performed for each address. In this example, only two slaves, ID1 and ID2, are shown, but in reality, many infrared slaves 2 will be arranged within the enclosure. The infrared master 1 is equipped with multiple LEDs as light-emitting elements and one photodiode as a light-receiving element. However, if the angle of the communication range is too wide for one light-receiving element to cover, it is possible to arrange multiple sets of one light-emitting element and one light-receiving element of the infrared master, rotating their orientations to address the issue. In Figure 3, only one photodiode is provided for LEDs a, b, c, and d. Instead, one photodiode is provided for LED a, one for LED b, and so on, so that a total of four photodiodes are provided for each individual LED.
[0018] Specifically, as shown in Figure 3, the infrared master 1 first transmits to infrared slave 2 with ID 1 using all LEDs at maximum intensity. In response, infrared slave 2 with ID 1 responds to infrared master 1 at maximum intensity. This process is based on the premise that if a slave exists, a response should be reliably given by both parties transmitting at maximum intensity. This leads to the determination that infrared slave 2 with ID 1 exists. If there is no response, it means that infrared slave 2 with ID 1 does not exist. This slave existence confirmation process is repeatedly executed for a predetermined number of addresses (for example, ID 1 to IDn).
[0019] In the second stage, a process is executed to search for the target LED to illuminate for each address, in order to determine which LED of the infrared master 1 should illuminate. Specifically, as shown in Figures 4(a), 4(b), and 4(c), the target LED is determined using a binary search method that eliminates the search target by half each time. First, the infrared master 1 transmits to the infrared slave 2 with ID 1 using two LEDs, a and b, at maximum intensity. In this situation, as shown in Figure 4(a), there is no response from the infrared slave 2 with ID 1. Next, after confirming that there is no response from the infrared slave 2 with ID 1, the infrared master 1 transmits to the infrared slave 2 with ID 1 using two LEDs, c and d, at maximum intensity. In this situation, as shown in Figure 4(b), the infrared slave 2 with ID 1 responds at maximum intensity. After that, the infrared master 1 further transmits to the infrared slave 2 with ID 1 using only LED c, at maximum intensity. In this situation, as shown in Figure 4(c), the infrared slave 2 with ID1 sends a response at maximum intensity. Through this series of processes, LED c is determined to be the LED that should be illuminated. This search process is repeatedly executed for a predetermined number of addresses (for example, ID1 to IDn).
[0020] In the third stage, as shown in Figure 5, the emission intensity of both infrared master 1 and infrared slave 2 is adjusted. The method involves performing a verification process in a loop, gradually increasing the emission intensity from the lowest level, and setting the intensity at the time communication is established as the adjusted intensity. This adjustment process is performed for both infrared master 1 and infrared slave 2. Although there is an argument that infrared master 1, which is powered by commercial power, can remain at maximum emission intensity, low power consumption is preferred, so the emission intensity of the master is also adjusted. Of course, the master can also be left unadjusted and fixed at maximum emission intensity. The emission intensity adjustment process is performed individually for each address. As a result, the emission intensity of the infrared slaves and the emission intensity of the LEDs targeted by the infrared master are adjusted for each individual combination, according to the individual installation conditions of multiple infrared slaves.
[0021] Thus, the light emission intensity adjustment is performed after the target LED is determined by binary search. However, in a configuration where each individual LED is assigned a photodiode, it is possible to search for the target LED in a short time without using binary search. The infrared master 1 transmits to the infrared slave 2 with ID 1 using all LEDs at maximum intensity. The infrared slave 2 with ID 1 adjusts the light emission intensity according to the strength of the received signal. Then, the infrared slave 2 transmits at the adjusted intensity, and in response, the infrared master 1 adjusts the light emission intensity of the LED paired with the photodiode that received the strongest signal according to the strength of the received signal of that photodiode. This is repeated for the number of addresses. Because the search determination and light emission intensity adjustment are performed simultaneously, and the search is not repeated as in binary search, the processing is performed quickly. From a hardware perspective, the cost is higher due to the increased number of photodiodes, but it can be seen that the light emission intensity can be adjusted without using binary search, and that the present invention is not limited by the specific search method for the target LED.
[0022] <Specific procedures for adjusting luminescence intensity> The software processing involved in adjusting the light intensity, which was described in the overview, will be explained in more detail using the flowcharts in Figures 6 to 11. This software is implemented in the firmware that is written to the product at the time of shipment. From this point forward, the infrared master and infrared slave will be simply referred to as master and slave.
[0023] Figures 6 to 10 show the processes performed on the master. Of these, Figure 6 is a flowchart showing the process performed to confirm the existence of the slave. On the right side of the flowchart, a schematic diagram is shown using the same infrared master 1 and infrared slave 2 as shown in Figures 3 to 5. The variables used in Figures 6 to 10 are defined as follows. i: Slave ID to communicate with (default value: 1) K: Maximum number of slaves (1 or more) N: Number of LEDs (1 or more) s(start): Variable representing the starting LED number of the light-emitting range (initial value: 1) m(middle): A variable representing the midpoint number of the LEDs within the light-emitting range (initial value: N / 2). e(end): Variable representing the end number of the LEDs within the light-emitting range (initial value: N) l: Variable indicating the light intensity of the LED (initial value: 1) Lmax: Maximum luminous intensity of the LED In the above, all values are integers, and any fractional parts resulting from division are truncated. Furthermore, the schematic diagram shows an example with the conditions i=1 and N=4.
[0024] In Figure 6, the loop (1) that starts after the start is a process that is repeated for each slave ID to be communicated, meaning that the light emission intensity adjustment is performed for each slave ID to be communicated. This repeated process is executed repeatedly until the slave ID reaches the maximum number K from 1.
[0025] (Slave existence check process) The slave presence confirmation process starts from step S101. First, in step S101, for the variable s representing the start number of the LEDs in the light emission target range, the variable e representing the end number of the LEDs in the light emission target range, the variable m representing the middle number of the LEDs in the light emission target range, and the variable l representing the light emission intensity of the LEDs, the variables are updated as s = 1, e = N, m = N / 2, l = Lmax. In step S102, the LEDs with numbers from s to e are set as the light emission targets. In step S103, a presence confirmation command is sent to the slave with ID i (initial value is 1), and in step S104, it is determined whether there is a response from the target slave. In the schematic diagram, the presence confirmation command is sent from all the LEDs of the master, and the state where there is a response from the slave with ID1 is shown. Different from the schematic diagram, if there is no response, in step S105, it is recorded in the log that the slave with ID i does not exist, and the process proceeds to step S124. Similar to the schematic diagram, if there is a response, the process proceeds to step S106.
[0026] (Light emission target LED search process) Figure 7 is a flowchart showing the process executed for the master and the process executed for searching for the light emission target LEDs. This process is also a loop process (2) that is repeatedly executed. The loop process (2) is repeatedly executed until s < e is not satisfied or there is no response from the slave under the condition that the LEDs with numbers from m + 1 to e are the light emission targets. In the schematic diagram on the right of the flowchart, the state of the first time of the loop process (2) is shown. In step S106, it is determined whether s < e, which is one of the end determination conditions of the loop process (2), holds. If it is No, the loop process (2) ends, and if it is Yes, the process proceeds to step S107. In step S107, the operation m = s + (e - s) / 2 is performed, and the decimal part of the operation result is truncated. In the first time of the loop process (2) shown in the schematic diagram, since m = 1 + (4 - 1) / 2 = 5 / 2, the truncated value 2 is updated as the variable m. In step S108, LEDs numbered s to m are set as targets for illumination. In the first iteration of loop processing (2) shown in the schematic diagram, LEDs 1 and 2 are set as targets for illumination. In step S109, a presence check command is sent to the slave with ID i, and in step S110, it is determined whether or not there is a response from the target slave. In the first iteration of the loop process (2) shown in the schematic diagram, a presence check command is sent to the slave with ID 1, but since LEDs 1 and 2 are not facing the slave with ID 1, it is shown that there is no response from the slave. Unlike the schematic diagram, if a response is received, the variable e=m is updated in step S111, and then the process returns to step S106. As in the schematic diagram, if there is no response, in step S112, LEDs numbered m+1 to e are set as the target for illumination. In the first iteration of loop processing (2) shown in the schematic diagram, LEDs 3 and 4 are set as the target for illumination. In step S113, a presence check command is sent to the slave with ID i, and in step S114, it is determined whether or not a response is received from the target slave. If a response is received, in step S115, the variable s is updated to s = m + 1. In the first iteration of loop processing (2) shown in the schematic diagram, a presence check command is sent to the slave with ID 1, and it is shown that a response was received from the slave. Therefore, the variable s will be updated to 3, as m + 1 = 2 + 1. Unlike the schematic diagram, if there is no response, the process exits loop processing (2) and proceeds to step S116.
[0027] Figure 8 is also a flowchart of the process performed on the master, specifically the process performed to search for the target LED to emit light. The schematic diagram on the right of the flowchart shows the second iteration of loop processing (2). Only the situations that differ from the first loop will be explained. In step S107, during the second iteration of the loop process (2) shown in the schematic diagram, m = 3 + (4 - 1) / 2 = 7 / 2, so this value is truncated to 3, and the variable m is updated. In step S108, in the second time of the loop process (2) shown in the schematic diagram, since both s and m are 3, only the 3 LEDs are the light-emitting targets. In step S110, in the second time of the loop process (2) shown in the schematic diagram, there is a response from the slave. In step S111, after the variable is updated to e = m and 3 is set in e, it returns to step S106. In step S106, since s < e does not hold, the process of loop (2) ends.
[0028] (Light emission intensity adjustment process) FIG. 9 is a flowchart showing a process executed for the master and a process executed for adjusting the light emission intensity. A loop process (3) is included in a part of the process. In the schematic diagram on the right of the flowchart, the state before the loop process (3) starts and the state of the first time of the loop process (3) are shown. In step S116, a light emission intensity adjustment command is sent to the slave with ID i. In step S117, it is determined whether there is a response from the target slave. If there is no response, the transmission of the light emission intensity adjustment command is repeated until a response is received. After a response is received, it proceeds to step S118. In step S118, a response for reception confirmation is sent to the slave with ID i. Regarding steps S116 to S118, in the schematic diagram on the right of the flowchart, for the slave with ID1, a light emission intensity adjustment command is sent, a response is received from the slave with ID1, and in response to this, the master sends a response for reception confirmation to the slave with ID1. So far, when sending a signal from the master, the variable of the light emission intensity l has been processed with l = Lmax. However, in step S1, the variable of the light emission intensity l is set to 1, and then the loop process (3) will start. The loop process (3) is repeatedly executed until there is a response from the slave with i or l = Lmax. In step S120, a command for checking the existence is sent to the slave with ID i. In step S121, it is determined whether a response is received from the target slave or whether l = Lmax is reached. If the answer is No, the process proceeds to step S122. In step S122, for the variable l indicating the emission intensity of the LED, after updating the variable to l = l + 1, the process returns to step S120. If the answer is Yes, the process exits the loop process (3) and proceeds to step S123. In the first time of the loop process (3) shown in the schematic diagram, although a command for checking the existence is sent from the master to the slave with ID1, it is shown that no response is received from the slave with ID1. Therefore, the variable l indicating the emission intensity of the LED is updated to l + 1 = 1 + 1, which becomes 2. Different from the schematic diagram, if the determination process in step S121 is Yes, the process exits the loop process (3) and proceeds to step S123. In step S123, the emission intensity to the slave of i and s(e) which is the LED number of the emission target are stored in the ROM. In step S124 which is the process following step S123 or the process following step S105, after updating the variable to i = i + 1, the process proceeds to step S125. In step S125, it is determined whether i < K holds. If Yes, the process returns to step S101. If No, the process exits the loop process (1) and ends all processes.
[0029] FIG. 10 is also a flowchart showing the process executed for the master and the process executed for adjusting the emission intensity. In the schematic diagram on the right of the flowchart, the second time of the loop process (3) is shown. Only the situation different from the first loop is explained. In steps S120 and S121, it is shown that a command for checking the existence is sent from the master to the slave with ID1 and a response is received from the slave with ID1. As a result, the process exits the loop process (3) and proceeds to step S123. In the second time of the loop process (3) shown in the schematic diagram, with l = 2 as the emission intensity, s = 3 is recorded as the emission target.
[0030] (Processing on the slave) We have so far described the processes performed on the master, but now we will also describe the processes performed on the slave. Figure 11 is a flowchart of the processes performed on the slave. Part of these processes includes loop processing (4). The schematic diagram on the right of the flowchart shows the state before loop processing (4) starts, and the state of loop processing (4) during the first and second iterations.
[0031] The variables used in Figure 11 are defined as follows: l: Variable indicating the light intensity of the LED (initial value: 1) Lmax: Maximum luminous intensity of the LED The schematic diagram shows an example where the condition i=1 is used.
[0032] In step S201, the variable l, which indicates the light emission intensity of the LED, is updated to l=Lmax. In step S202, it is determined whether or not the slave existence confirmation command repeatedly sent by the master has been received during the slave existence confirmation process and the LED target search process for the master, as described earlier. If it has been received, a response signal is sent back to the master in step S203. This process is repeated until a light emission intensity adjustment command is received from the master. The schematic diagram on the right of the flowchart illustrates this process. In step S204, it is determined whether or not a light intensity adjustment command has been received from the master. If no, the process returns to step S202; if yes, the process proceeds to step S205 to start the light intensity adjustment process. Up to this point, the variable for light emission intensity l has been processed with l=Lmax during signal transmission from the slave. However, in step S205, the variable for light emission intensity l is set to 1, and loop processing (4) begins. Loop processing (4) is executed repeatedly until a response is received from the master or until l=Lmax. In step S206, a response to the previously received light intensity adjustment command is sent with a light intensity l (initial value 1). In step S207, it is determined whether or not there is a response from the master, or whether or not l = Lmax. If No, the process proceeds to step S208, where the variable l, which indicates the light intensity of the LED, is updated to l = l + 1, and then the process returns to step S206. If Yes, the process exits loop processing (4) and returns to step S202. In the first iteration of loop processing (4) shown in the schematic diagram, the slave responds with a light intensity of 1, but there is no response from the master. After the variable l, which indicates the light intensity of the LED, is updated to l + 1 = 1 + 1, the second iteration of loop processing (4) is executed, and this time the slave responds with a light intensity of 2, and there is a response from the master.
[0033] So far, we have described the adjustment of light emission intensity performed collaboratively by an infrared master and an infrared slave. However, the flowchart described is merely an example, and does not prevent the adoption of other processing flows. Any method can be used as long as it is possible to adjust the light emission intensity of both the master and the slave after determining the target LED. For example, if the infrared master has a photodiode for each individual LED, the target LED can be determined using a simpler method without using a binary search. Also, if the slave devices are arranged in an orderly manner, and the infrared slaves are also installed in the housing with their positions predetermined in an orderly manner, then the LED target search process itself may be omitted, and only the light emission intensity adjustment process may be executed, taking the position of the slaves as a given.
[0034] Furthermore, in the flowchart of the embodiment, under the premise that lower power consumption is preferable, the emission intensity of not only the infrared slave but also the infrared master was adjusted. However, for infrared masters powered by commercial power, it is possible to omit the emission intensity adjustment. Nevertheless, even if the infrared master is configured to emit light at maximum intensity without emission intensity adjustment, one LED will be selected from among the multiple LEDs provided by the infrared master to emit light, which in turn contributes to power consumption.
[0035] The optical wireless communication fieldbus or infrared communication fieldbus according to the embodiments of the present invention described above will not be affected by interference from other radio wave communications. In recent years, as local 5G has become increasingly widespread in factories and businesses, the ability to realize a communication environment independent of radio wave communications through optical wireless communication is a significant advantage. In addition, it is advantageous in that it is difficult to intercept or spoof communications because the area in which communication is possible can be restricted, and it does not require certification under the Radio Law, making it easy to deploy in various countries. Furthermore, the fact that the light emission intensity of each slave is individually adjusted according to the individual installation conditions of multiple slaves provides a significant advantage in terms of low power consumption.
[0036] <Note> As mentioned above, according to the infrared communication fieldbus embodiment of the present invention, power consumption can be reduced because the light emission intensity is individually adjusted according to the individual installation conditions of multiple infrared slaves. However, the fact that power consumption is reduced by adjusting the light emission intensity also applies even if there is only one slave instead of multiple. In the case of one slave, i=K=1 in the process shown in the flowchart of Figure 6. Below, the technical ideas that can be conceived from this perspective are presented in the form of an addendum.
[0037] (Note 1) A fieldbus used for communication between peripheral and control devices located within the casing of industrial equipment, The fieldbus consists of an optical wireless master and at least one optical wireless slave that transmit and receive signals via optical wireless communication. The optical wireless master comprises a plurality of light-emitting elements and at least one light-receiving element. Depending on the installation status of the optical wireless slave, at least the light emission intensity of the optical wireless slave is individually adjusted. An optical wireless communication fieldbus characterized by the following features.
[0038] (Note 2) Depending on the installation status of the optical wireless slave, the light emission intensity of the multiple light-emitting elements of the optical wireless master is further adjusted relative to the optical wireless slave. The optical wireless communication fieldbus described in (Appendix 1), characterized by the above.
[0039] Although the optical wireless communication fieldbus, industrial equipment, and light intensity adjustment method according to embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and any design changes, etc., that do not depart from the gist of the present invention are also included. For example, even if the placement location is unknown, if it is known with certainty that an infrared slave of the target ID exists, the process of full search can be omitted without falling outside the scope of the present invention. Furthermore, although this specification specifically describes examples using infrared communication, the technical concepts conveyed here are not limited to infrared communication. It should be correctly understood that the advantages of not being affected by interference from other radio wave communications and being able to limit the communication area apply equally to visible light communication and ultraviolet communication. [Explanation of Symbols]
[0040] 1. Infrared Master (Optical Wireless Master) 11 Superior equipment 2. Infrared Slave (Optical Wireless Slave) 21 Slave device 3 cabinets 4 partition plates
Claims
1. A fieldbus used for communication between peripheral and control devices located within the casing of industrial equipment, The fieldbus consists of an optical wireless master and multiple optical wireless slaves that transmit and receive signals using optical wireless communication. The aforementioned optical wireless master comprises a plurality of light-emitting elements and at least one light-receiving element. Depending on the individual installation conditions of the plurality of optical wireless slaves, at least the light emission intensity of each optical wireless slave is individually adjusted. Each optical wireless slave is mounted in an arbitrary position without a predetermined placement location. The placement position of each optical wireless slave is determined by a binary search method by selectively illuminating all or some of the multiple light-emitting elements of the optical wireless master, and When an individual optical wireless slave receives a light emission intensity adjustment command from a predetermined light-emitting element of the optical wireless master, it repeatedly performs the process of gradually increasing the light emission intensity from the lowest level and transmitting a response signal to the optical wireless master. The light emission intensity at the time of receiving a reply signal from the optical wireless master in response to the response signal is determined as the adjusted light emission intensity. An optical wireless communication fieldbus characterized by the following features.
2. Prior to determining the placement location using the binary search method, a process for confirming the existence of each individual optical wireless slave is performed. The optical wireless communication fieldbus according to feature 1.
3. The optical wireless communication fieldbus described in claim 1 or 2 is provided, and communication between peripheral devices and control devices is performed via the optical wireless communication fieldbus. Industrial equipment characterized by the following features.
4. A method for adjusting the light emission intensity between an optical wireless master and an optical wireless slave in an optical wireless fieldbus used for communication between peripheral and control equipment located within the enclosure of industrial equipment, The optical wireless slave receives a light emission intensity adjustment command from the optical wireless master, A response signal transmission step in which the optical wireless slave transmits a response signal to the optical wireless master at the lowest level of light emission intensity, A slave-side verification step to confirm whether the optical wireless slave has received a reply signal from the optical wireless master in response to the response signal. The slave-side confirmation step includes, at least, a slave-side adjustment step in which, if the reception of the reply signal is not confirmed, the optical wireless slave re-transmits a response signal to the optical wireless master with a light emission intensity increased by one level, and if the reception of the reply signal is confirmed, the adjustment light emission intensity of the optical wireless slave is determined. If necessary, the steps from the slave-side verification step to the slave-side adjustment step are repeatedly performed. The optical wireless master transmits a light intensity adjustment command at the maximum level of light intensity, and then receives a reception acknowledgment response signal from the optical wireless slave. The optical wireless master transmits a presence confirmation signal to the optical wireless slave at the lowest level of light emission intensity. A master-side verification step in which the optical wireless master confirms whether or not it has received a response signal from the optical wireless slave to the presence confirmation signal, In the master-side confirmation step, if the reception of the response signal is not confirmed, the optical wireless master transmits a presence confirmation signal to the optical wireless slave again with a light emission intensity one level higher, and if the reception of the response signal is confirmed, the master-side adjustment step includes at least the determination of the adjusted light emission intensity of the optical wireless master. If necessary, the steps from the master side verification step to the master side adjustment step are repeatedly executed. A method for adjusting the intensity of light emission, characterized by the following features.