JP2021136481A - Transmission apparatus - Google Patents

Abstract

To achieve a trial frequency according to the nature of each access to a common memory for internal process in a transmission system in which each transmission apparatus has a common memory.SOLUTION: The transmission apparatus includes: a common memory; a first processing unit which accesses the common memory when performing data transmission/reception to/from another transmission apparatus; a second processing unit which accesses the common memory for internal processing; an arbitration unit which, when the first processing unit is not accessing the common memory, permits accessing from the second processing unit to the common memory, whereas when the first processing unit is accessing the common memory, does not permit accessing from the second processing unit to the common memory; and a notification unit which notifies the second processing unit of a network configuration information transmission time zone. An access trial frequency to the common memory is different dependent on the network configuration information transmission time zone and a control data transmission time zone.SELECTED DRAWING: Figure 2

Description

Embodiments of the present invention relate to transmission devices.

Conventionally, for example, in an industrial plant or the like, in a transmission system in which transmission devices such as PLC (Programmable Logic Controller) and input / output devices are connected by a network, a technique of arranging a common memory for sharing data in each transmission device has been used. be.

Then, in general, when a common memory is used when transmitting / receiving data to / from another transmission device, each transmission device is transferred to the common memory for internal processing (processing in its own transmission device). Access is not allowed. Further, when the network configuration information transmission time zone and the control data transmission time zone are periodically repeated in the transmission system, the network configuration information transmission time zone is generally the time used rather than the control data transmission time zone. The ratio is small.

Japanese Patent No. 4335327 Japanese Patent No. 3766377 Japanese Unexamined Patent Publication No. 2011-059915

However, in the above-mentioned conventional technique, when it becomes necessary to access the common memory for internal processing in the transmission device, the common memory is returned to the common memory at a constant frequency regardless of which of the above-mentioned time zones. Since I was trying to access the device, I could not realize the frequency of trying according to the nature (urgency, etc.) of each access.

Therefore, this embodiment has been made in view of the above circumstances, and in a transmission system in which each transmission device has a common memory, the frequency of trials according to the property of each access to the common memory for internal processing is set. An object is to provide a feasible transmission device.

The transmission device of the embodiment includes a common memory that stores data transmitted / received by broadcast communication with another transmission device in a transmission system in which a plurality of transmission devices are connected by a network, and the other transmission device. A first processing unit that accesses the common memory when transmitting and receiving data, a second processing unit that accesses the common memory for internal processing, and the first processing unit are connected to the common memory. When not accessing, the second processing unit is allowed to access the common memory, and when the first processing unit is accessing the common memory, the second processing unit is allowed to access the common memory. In the second transmission system, the arbitration unit that does not allow access to the data, the network configuration information transmission time zone, and the control data transmission time zone are periodically repeated, and the network configuration information transmission time zone is defined as the network configuration information transmission time zone. It includes a notification unit that notifies the processing unit. The second processing unit makes the frequency of trials for access to the common memory different between the network configuration information transmission time zone and the control data transmission time zone.

FIG. 1 is a diagram showing an outline of the overall configuration of the transmission system of the first embodiment. FIG. 2 is a diagram showing an outline of the configuration of the transmission device of the first embodiment. FIG. 3 is an explanatory diagram of a transmission time zone in the transmission system of the first embodiment. FIG. 4 is a flowchart showing processing by the transmission device of the first embodiment. FIG. 5 is a diagram showing an outline of the configuration of the transmission device of the second embodiment. FIG. 6 is a diagram showing an outline of the configuration of the transmission device of the comparative example.

Hereinafter, the transmission device of the embodiment will be described with reference to the drawings. In order to facilitate understanding, first, a comparative example (conventional technique) will be described. FIG. 6 is a diagram showing an outline of the configuration of the transmission device of the comparative example.

In a transmission system in which a plurality of transmission devices are connected by a network, when the CPU tries to access the common memory in the transmission device and the common memory access unit does not access the common memory, the arbiter circuit is transmitted from the CPU. Allow access to common memory.

When the common memory access unit is accessing the common memory, the arbiter circuit outputs a wait signal to the CPU, and the CPU holds the access and waits. The CPU accesses the common memory after releasing the wait signal. When the CPU and the common memory access unit try to access the common memory at the same time, the arbiter circuit gives priority to the access from the common memory access unit. That is, when the CPU tries to access the common memory, it is affected by the access status from the common memory access unit to the common memory.

Further, in the transmission device, when it becomes necessary to access the common memory for internal processing, it is common at a constant frequency regardless of whether the time zone is the network configuration information transmission time zone or the control data transmission time zone. Since we were trying to access the memory, we could not realize the trial frequency according to the nature (urgency, etc.) of each access.

Therefore, in the following, in a transmission system in which each transmission device has a common memory, a technique capable of realizing a trial frequency according to the property of each access to the common memory for internal processing will be described.

(First Embodiment)
FIG. 1 is a diagram showing an outline of the overall configuration of the transmission system S of the first embodiment. The transmission system S includes a plurality of transmission devices 1 connected by a network N. The transmission system S is used, for example, in an industrial plant or the like. In that case, the transmission device 1 is, for example, a PLC or an input / output device.

Further, in the transmission system S, the transmission right of each transmission device 1 is determined by, for example, a token passing method. That is, among the plurality of transmission devices 1, the transmission device 1 that has received the token has the right to transmit data. The transmission device 1 that has acquired the right to transmit data transmits data to all other transmission devices 1 by broadcast communication.

FIG. 2 is a diagram showing an outline of the configuration of the transmission device 1 of the first embodiment. The transmission device 1 includes a transmission board 2, a memory 3, a CPU 4 (second processing unit), an arbiter circuit 5 (arbitration unit), and a common memory 6. In FIG. 2, the arrows indicate the main flow of data, and data is transmitted and received as needed even in the portion without the arrows (the same applies to FIG. 5).

The transmission board 2 includes a transmission / reception unit 21, a common memory access unit 22 (first processing unit), a control unit 23, and a notification unit 24.

The transmission / reception unit 21 transmits / receives data to / from another transmission device 1 via the network N. When the transmission / reception unit 21 transmits / receives data to / from another transmission device 1, the common memory access unit 22 accesses the common memory 6 to read / write data.

The control unit 23 controls the transmission / reception unit 21 and the notification unit 24. Further, in the transmission system S, the network configuration information transmission time zone and the control data transmission time zone are periodically repeated. Here, FIG. 3 is an explanatory diagram of a transmission time zone in the transmission system S of the first embodiment. The network configuration information transmission time zone is, for example, a time zone in which information (network configuration information) is transmitted / received when the transmission device 1 is added or deleted from the transmission system S. The control data transmission time zone is a time zone for transmitting and receiving data related to the control of the transmission device 1 and sensing data by various sensors (not shown) under the control device 1. In general, since the transmission device 1 is not frequently added or deleted from the transmission system S, the network configuration information transmission time zone has a smaller ratio of the time used than the control data transmission time zone.

Returning to FIG. 2, the notification unit 24 notifies the CPU 4 that it is the network configuration information transmission time zone according to the command from the control unit 23 (details will be described later).

The memory 3 is, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), a flash memory, or the like.

The CPU 4 uses the memory 3 to execute various arithmetic processes. Further, the CPU 4 accesses the common memory 6 for internal processing. The CPU 4 accesses the common memory 6 in order to write the sensing data of various sensors (not shown) under the transmission device 1 to the common memory 6, for example.

Further, the CPU 4 makes the frequency of trying to access the common memory 6 different between the network configuration information transmission time zone and the control data transmission time zone (details will be described later).

The arbitr circuit 5 allows the CPU 4 to access the common memory 6 when the common memory access unit 22 is not accessing the common memory 6, and the CPU 4 when the common memory access unit 22 is accessing the common memory 6. Do not allow access to common memory 6 by.

The common memory 6 shares data with another transmission device 1. That is, the common memory 6 stores data transmitted / received by broadcast communication with another transmission device 1. The memory space of the common memory 6 is divided into, for example, a storage area for storing transmission data and a storage area for storing data broadcast from another transmission device 1. Further, the storage area of the storage destination of each data is predetermined.

Next, the operations of the notification unit 24 and the CPU 4 will be described in detail. For example, the notification unit 24 notifies the CPU 4 of the start timing of the network configuration information transmission time zone. Then, the CPU 4 recognizes the time within a predetermined time after receiving the start timing as the network configuration information transmission time zone. Then, for example, the CPU 4 makes the trial frequency of the network configuration information transmission time zone higher than the trial frequency of the control data transmission time zone. As described above, in general, the network configuration information transmission time zone has a smaller percentage of the time used than the control data transmission time zone, which improves the success rate of the access try to the common memory 6 by the CPU 4. be able to. This is particularly effective when the urgency of the access is low.

Further, for example, the notification unit 24 may notify the CPU 4 of the start timing and the end timing of the network configuration information transmission time zone.

Further, for example, the CPU 4 may set the try frequency in the network configuration information transmission time zone to be less than the try frequency in the control data transmission time zone. This is particularly effective when the urgency of the access is high. That is, although the success rate of access trials is low in the control data transmission time zone, the time required for successful access can be shortened by increasing the trial frequency.

Next, the process by the transmission device 1 of the first embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing processing by the transmission device 1 of the first embodiment.

First, in step S1, the CPU 4 determines whether or not it is necessary to access the common memory 6 for internal processing. If Yes, the process proceeds to Step S2, and if No, the process returns to Step S1.

In step S2, the arbiter circuit 5 determines whether or not the common memory 6 is being used by the common memory access unit 22, and in the case of Yes, the CPU 4 is not allowed to access the common memory 6 and the step S4 is performed. If No, the CPU 4 is allowed to access the common memory 6, and the process proceeds to step S3.

In step S3, the CPU 4 accesses the common memory 6.

In step S4, the control unit 23 determines whether or not the current network configuration information transmission time zone is set, and if Yes, the process proceeds to step S5, and if No, the process proceeds to step S6.

In step S5, the CPU 4 tries to access the common memory 6 with high frequency (higher frequency than the control data transmission time zone). In step S6, the CPU 4 tries to access the common memory 6 at a normal frequency.

After steps S5 and S6, in step S7, the CPU 4 determines whether or not the access to the common memory 6 is successful, and if Yes, the process ends, and if No, the process returns to step S2.

In this way, according to the transmission device 1 of the first embodiment, the CPU 4 makes the access trial frequency to the common memory 6 different between the network configuration information transmission time zone and the control data transmission time zone, so that the internal processing can be performed. It is possible to realize the trial frequency according to the property of each access to the common memory 6.

For example, when the urgency of access is low, the CPU 4 makes the try frequency of the network configuration information transmission time zone higher than the try frequency of the control data transmission time zone. As a result, the success rate of the access try to the common memory 6 by the CPU 4 can be improved.

Further, for example, when the urgency of access is high, the CPU 4 tries more frequently in the control data transmission time zone than in the try frequency in the network configuration information transmission time zone. As a result, the time required for the CPU 4 to successfully access the common memory 6 can be shortened.

(Second Embodiment)
Next, the transmission device 1 of the second embodiment will be described. Overlapping description of the same items as in the first embodiment will be omitted as appropriate. FIG. 5 is a diagram showing an outline of the configuration of the transmission device 1 of the second embodiment. The transmission device 1 of FIG. 5 is different from the transmission device 1 of FIG. 2 in that a counter 7, a bus interface 8 and 9 are added.

The counter 7 is a means for counting the time according to a command from the notification unit 24. The counter 7 may be realized by either software or hardware. The CPU 4 is connected to the arbiter circuit 5 via the bus interfaces 8 and 9.

The notification unit 24 sets the network configuration time in the counter 7. By accessing the counter 7, the CPU 4 can identify whether or not the current network configuration information transmission time zone is set.

In this way, according to the transmission device 1 of the second embodiment, the CPU 4 accesses the counter 7 to identify whether or not the current network configuration information transmission time zone is present, and the network configuration information transmission time. The frequency of access trials to the common memory 6 can be different depending on the band and the control data transmission time zone. As a result, it is possible to realize a trial frequency according to the property of each access to the common memory 6 for internal processing.

The program executed by the transmission device 1 of each embodiment is provided, for example, by being incorporated in a ROM or the like in advance. In addition, the program is recorded on a computer-readable recording medium such as a CD-ROM, flexible disk (FD), CD-R, or DVD (Digital Versatile Disk) as an installable or executable file. May be configured to provide.

Further, the program may be stored on a computer connected to a network such as the Internet and provided by downloading via the network. Further, the program may be configured to be provided or distributed via a network such as the Internet.

Further, the program has a module configuration including each part in the transmission device 1, and as actual hardware, the CPU (processor) reads the program from the ROM and executes the program so that each part is on the main storage device. It is designed to be loaded and generated.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Transmission device, 2 ... Transmission board, 3 ... Memory, 4 ... CPU, 5 ... Arbiter circuit, 6 ... Common memory, 7 ... Counter, 8 ... Bus interface, 9 ... Bus interface, 21 ... Transmitter / receiver, 22 ... Common Memory access unit, 23 ... control unit, 24 ... notification unit, S ... transmission system

Claims (5)

A common memory that stores data transmitted and received by broadcast communication with other transmission devices in a transmission system in which multiple transmission devices are connected via a network, and
A first processing unit that accesses the common memory when transmitting / receiving data to / from another transmission device,
A second processing unit that accesses the common memory for internal processing,
When the first processing unit is not accessing the common memory, the second processing unit is permitted to access the common memory, and when the first processing unit is accessing the common memory. Is an arbitration unit that does not allow access to the common memory by the second processing unit, and
In the transmission system, the network configuration information transmission time zone and the control data transmission time zone are periodically repeated, and the notification unit notifies the second processing unit that the network configuration information transmission time zone is set. , Equipped with
The second processing unit is a transmission device that makes the frequency of trials for access to the common memory different between the network configuration information transmission time zone and the control data transmission time zone. The notification unit notifies the second processing unit of the start timing of the network configuration information transmission time zone.
The transmission device according to claim 1, wherein the second processing unit recognizes the network configuration information transmission time zone within a predetermined time after receiving the start timing. The transmission device according to claim 1, wherein the notification unit notifies the second processing unit of the start timing and the end timing of the network configuration information transmission time zone. The transmission device according to claim 1, wherein the second processing unit increases the try frequency in the network configuration information transmission time zone to be higher than the try frequency in the control data transmission time zone. The transmission device according to claim 1, wherein the second processing unit reduces the try frequency in the network configuration information transmission time zone to be lower than the try frequency in the control data transmission time zone.

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