JP7739716B2 - Communication unit, network system, output unit control method and control program - Google Patents

Description

The present invention relates to a control method and control program for a communication unit, a network system, and an output unit.

In the field of factory automation (FA), various types of devices that share work processes are controlled. To coordinate the operation of the various controllers, remote I/O, and manufacturing equipment used in work in a specific area such as a factory facility, industrial network systems, also known as field networks, are constructed to connect these devices.

General industrial network systems use master-slave networks consisting of various slave devices and master devices. Slave devices are devices that control or collect data from equipment installed in a factory. Master devices are devices called programmable logic controllers (PLCs), for example, that centrally manage these slaves. EtherCAT (registered trademark) and Ethernet/IP (registered trademark) are examples of industrial network system formats (ETHERNET (registered trademark)). In such industrial network systems, communication cables are laid between each device to create a network.

A related technology is disclosed in Patent Document 1 below. Patent Document 1 relates to a communications system for controlling factory automation equipment and the like in a bus-type network, which is composed of a master station that manages the network and slave stations that control I/O, etc. In this communications system, when a communication abnormality is detected, a partial communication suspension mode can be set as the master station's abnormality operation mode, which determines whether to continue communication with slave stations included in the remote I/O system. This mode suspends communication only with the slave station where the abnormality occurred, and continues the communication abnormality state without executing a subscription solicitation process to resume communication with that slave station, while continuing normal communication with other slave stations where no communication abnormality has occurred.

Japanese Patent Application Laid-Open No. 2007-312043

In the network system described above, a system may be constructed in which a communication unit for controlling the IO units is provided between the master device and IO units such as input units and output units. This communication unit controls the IO units in response to instructions from the master device, but if the instructions from the master device are lost due to debugging or other reasons, the communication unit will maintain the state of the output unit before the instructions from the master device were lost. Therefore, even if the output data sent to the output unit is invalid, the output unit will continue to output a constant value, resulting in a lack of flexibility as a system.

However, even if the technology disclosed in Patent Document 1 mentioned above is used, it is not possible to solve this problem.

The present invention was made in consideration of the above problems, and aims to realize a communication unit that can maintain system flexibility even when instructions from the master device are no longer received.

To solve the above-mentioned problems, the present invention adopts the following configuration.

A communication unit according to one aspect of the present invention includes a first communication unit that communicates with a master device via a network, a second communication unit that communicates with an output unit via a local bus, and a control unit that, when instructions cannot be received from the master device via the first communication unit, controls the second communication unit to notify the output unit that output data received from the master device and to be transmitted to the output unit is invalid.

With the above configuration, if the control unit is unable to receive instructions from the master device, it controls the second communication unit to notify the output unit that the output data received from the master device and sent to the output unit is invalid. This allows the output unit to output according to the user's settings, improving system flexibility.

In the communication unit according to the above aspect, the communication unit further includes a memory unit that stores load shedding data corresponding to the output unit, and the control unit controls the second communication unit to notify the output unit of the load shedding data stored in the memory unit when instructions cannot be received from the master device via the first communication unit.

The above configuration allows appropriate load shedding data to be set for the output unit.

A network system according to one aspect of the present invention comprises a master device and a communication unit. The communication unit includes a first communication unit that communicates with the master device via the network, a second communication unit that communicates with the output unit via a local bus, and a control unit that controls the second communication unit to notify the output unit that output data received from the master device and to be transmitted to the output unit is invalid when instructions from the master device cannot be received via the first communication unit.

With the above configuration, if the control unit is unable to receive instructions from the master device, it controls the second communication unit to notify the output unit that the output data received from the master device and sent to the output unit is invalid. This allows the output unit to output according to the user's settings, improving system flexibility.

A method for controlling an output unit according to one aspect of the present invention includes the steps of receiving from the master device that the master device is in a state where it is not issuing instructions, and notifying the output unit that the output data received from the master device and to be output to the output unit is in an invalid state.

With the above configuration, the output unit is notified that the output data received from the master device and output to the output unit is invalid, allowing the output unit to output according to the user's settings, thereby increasing system flexibility.

A control program according to one aspect of the present invention is a computer program for causing a computer to execute a control method for an output unit, the control method including the steps of receiving from the master device that the master device is in a state where it is not issuing instructions, and notifying the output unit that the output data received from the master device and to be output to the output unit is in an invalid state.

With the above configuration, the output unit is notified that the output data received from the master device and output to the output unit is invalid, allowing the output unit to output according to the user's settings, thereby increasing system flexibility.

Any of the communication unit according to one aspect of the present invention, the network system according to one aspect of the present invention, the control method for an output unit according to one aspect of the present invention, and the control program for an output unit according to one aspect of the present invention can provide system flexibility.

FIG. 2 is a block diagram showing a functional configuration of a communication gateway device according to an embodiment of the present invention. 1 is a diagram showing a schematic configuration of a network system according to an embodiment of the present invention; 4 is a flowchart illustrating a processing procedure of the communication gateway device according to the embodiment of the present invention.

Below, an embodiment of one aspect of the present invention (hereinafter also referred to as "this embodiment") will be described with reference to the drawings.

1 is a block diagram showing the functional configuration of a communication gateway device 10 included in a network system 1 according to an embodiment of the present invention. The network system 1 includes the communication gateway device 10, a master device 20, external input devices 61a, 61c and external output devices 61b, 61d controlled by a unit 11 belonging to a stand-alone system, and external input devices 71a, 71c and external output devices 71b, 71d controlled by a unit 12 belonging to a remote IO system. Hereinafter, the input units and output units may be collectively referred to as IO units.

The master device 20 is connected to the communication gateway device 10 via a communication network (hereinafter referred to as the upper network) such as EtherNet/IP (registered trademark), and controls the communication gateway device 10 via the upper network. The master device 20 may also be a device such as a PLC.

When the master device 20 is controlling the communication gateway device 10 via the upper network (operating mode), the communication gateway device 10 controls the IO units 41a-41d and 51a-51d in response to instructions from the master device 20. When the master device 20 is in operating mode, it is called the Run state, and the master device 20 notifies the communication gateway device 10 that it is in the Run state and sends output data to be set in the output units to the communication gateway device 10.

Furthermore, when the master device 20 is debugging a program or the program is operating abnormally during operation (program mode), the communication gateway device 10 is unable to receive instructions from the master device 20 and operates as described below. When the master device 20 is in program mode, it is in what is called the Idle state, and the master device 20 notifies the communication gateway device 10 that it is in the Idle state. The Run state and Idle state described above are referred to as upper communication modes.

The communication gateway device 10 includes a communication unit 10A, a unit 11 belonging to a standalone system, and a unit 12 belonging to a remote IO system. The communication unit 10A also includes a first communication unit 13 and a second communication unit 14. The first communication unit 13 is connected to the master device 20 via a communication network (higher-level network) such as EtherNet/IP (registered trademark).

The second communication unit 14 includes a control unit 141 and a local bus communication unit 142. Under the control of the control unit 141, the local bus communication unit 142 communicates with the logic control unit 111, input units 41a, 41c, 51a, 51c, and output units 41b, 41d, 51b, 51d, which are connected to the local bus (lower network).

The standalone system can independently control the IO units 41a to 41d without instructions from the master device 20. The standalone system includes a logic control unit 111, input units 41a and 41c, and output units 41b and 41d.

The logic control unit 111 controls the input units 41a and 41c and the output units 41b and 41d via the local bus communication section 142. For example, the logic control unit 111 controls the input units 41a and 41c to receive input data from the external input devices 61a and 61c. The logic control unit 111 then performs calculations based on the input data, controls the output units 41b and 41d in accordance with the calculation results, and controls the external output devices 61b and 61d.

The master device 20 monitors the operation of the standalone system and communicates with it as appropriate. Therefore, the standalone system can operate independently whether the upper communication mode is in Run or Idle state.

On the other hand, the remote IO system includes input units 51a and 51c and output units 51b and 51d. It controls IO units 51a to 51d in response to instructions from master device 20. For example, in response to instructions from master device 20, the remote IO system transmits input data from external input devices 71a and 71c connected to input units 51a and 51c to master device 20 via first communication unit 13. In response to the received input data, master device 20 transmits instructions (output data) to the remote IO system, and the remote IO system sets the output data in output units 51b and 51d in response to instructions from master device 20. This enables control of external output devices 71b and 71d.

When the control unit 141 receives a higher-level communication mode in the Run state from the master device 20 via the first communication unit 13, it controls the local bus communication unit 142 in response to instructions from the master device 20. That is, in response to instructions from the master device 20, the control unit 141 receives input data from external input devices 71a and 71c via input units 51a and 51c and transmits it to the master device 20 via the first communication unit 13, and controls external output devices 71b and 71d by controlling output units 51b and 51d in response to the output data received from the master device 20.

The output unit 51b includes a control unit 511 and a memory unit 512. The memory unit 512 is composed of RAM (Random Access Memory), flash memory, etc., and stores setting data (hereinafter also referred to as load shedding data) to be set in the output unit 51b when the upper communication mode is in the Idle state. Different load shedding data is stored for each of the multiple output units.

When the control unit 141 receives an upper communication mode in the Idle state (a state in which instructions cannot be received from the master unit 20) from the master device 20 via the first communication unit 13, the control unit 511 reads the load shedding data stored in the memory unit 512 and sets the load shedding data in the output unit 51b. This allows the output unit 51b to output according to the user's settings, making the system more flexible.

In addition, the communication unit 10A may have a memory unit that stores the load shedding data to be set for the output units 51b and 51d, and when it receives an upper communication mode in the Idle state from the master device 20, it may refer to the memory unit and set the load shedding data for all output units.

§2 Configuration example (overall overview of network system 1)
2 is a diagram showing a schematic configuration of a network system 1 including a communication gateway device 10 according to an embodiment of the present invention. The network system 1 includes the communication gateway device 10, a master device 20, a hub device 30, external input devices 61 a and 61 c and external output devices 61 b and 61 d controlled by a stand-alone system, and external input devices 71 a and 71 c and external output devices 71 b and 71 d controlled by a remote IO system.

The master device 20 and communication gateway device 10 are connected by a higher-level network via a hub device 30. The communication gateway device 10 comprises a communication unit 10A, a unit 11 belonging to a standalone system, and a unit 12 belonging to a remote IO system. As shown in Figure 2, the standalone system and remote IO system are provided with multiple IO units for connecting external input and output devices, and connections to external input and output devices are possible by connecting cables.

In FIG. 2, external input devices 61a, 61c and external output devices 61b, 61d connected to unit 11 belonging to the standalone system belong to standalone system group 60 and are assigned to the standalone system. Furthermore, external input devices 71a, 71c and external output devices 71b, 71d connected to unit 12 belonging to the remote IO system belong to remote IO system group 70 and are assigned to master device 20.

Table 1 below shows an example of the specifications of an output unit. This output unit is an analog output unit, and lists the settings that are set in the output unit when the upper communication mode transitions from Run state to Idle state.

As shown in the first setting in Table 1, when "Hold Output" is selected, the output unit will hold the value immediately before the abnormality occurred and output that value. In Run mode, the output range voltage can be set between -10V and +10V, and the current can be set between 4 and 20mA. In Idle mode, the upper limit can be set to 11V or 20.8mA, and the lower limit can be set to -11V or 3.2mA.

As shown in the second setting in Table 1, when "Lower limit output" is set, the output unit will output the lower limit of each output range (-11V, 3.2mA). Also, as shown in the third setting in Table 1, when "Upper limit output" is set, the output unit will output the upper limit of each output range (11V, 20.8mA).

As shown in the fourth setting in Table 1, when "User-specified value output" is set, the output unit will output the value specified by the user. Also, as shown in the fifth setting in Table 1, when "0 output" is set, the output unit will output the analog value when the output setting value for each output range is "0."

Table 2 below shows an example of the specifications of an output unit. This output unit is a digital output unit, and lists the settings that are set in the output unit when the upper communication mode transitions from Run state to Idle state.

As shown in Table 2, output contacts 00 and 01 can be set to output when a load is cut off; if 0 (FALSE), the output is turned OFF; if 1 (TRUE), the current output value is maintained. The initial values of output contacts 00 and 01 are both FALSE.

When the upper communication mode is in Run state, the remote IO system is in OP (operation) state, and is running while performing IO refresh. Here, IO refresh is divided into IN refresh and OUT refresh. IN refresh is the operation of inputting input data from the input unit. OUT refresh is the operation of updating the output of the output unit.

When the upper communication mode is in the Idle state, the remote IO system is in the SafeOP (safe operation) state, and only IN refresh is performed, not OUT refresh. Therefore, only input data from the input unit is valid. At this time, as described above, the control unit 511 reads the load shedding data stored in the memory unit 512 and sets it in the output unit 51b.

An example of an external output device controlled by the output unit is a device that performs temperature control. If this temperature control device is at a high temperature and the upper communication mode transitions to Idle, the temperature control device will remain at a high temperature, compromising safety. Safety may also be compromised if the temperature drops suddenly when the output of the temperature control device is turned off. The setting data (load shedding data) stored in the memory unit 512 is set to a value that will set the temperature so that this situation does not occur.

Furthermore, when the output unit controls a servo motor, if the drive waveform for driving the servo motor becomes fixed or if the drive waveform continues to be output, the safety of the device controlled by the servo motor may be compromised. When such external output equipment is controlled by the output unit, when the upper communication mode enters the Idle state, the control unit 511 reads the load shedding data stored in the memory unit 512 and sets it in the output unit 51b, thereby preventing safety from being compromised.

3 is a flowchart for explaining the processing procedure of the communication gateway device 10 according to the embodiment of the present invention. First, the control unit 141 receives output data from the master device 20 via the first communication unit 13 (S1).

Next, the control unit 141 receives the upper communication mode from the master device 20 via the first communication unit 13 (S2). If the previously received upper communication mode was the Run state and the currently received upper communication mode is the Idle state (S3, Run to Idle), the control unit 141 transitions the IO units 51a to 51d belonging to the remote IO system group 70 to the SafeOP state (S4), and processing proceeds to step S7.

At this time, the control unit 141 notifies the output units 51b and 51d via the local bus communication unit 142 that they have transitioned from the OP state to the SafeOP state, and that the output data from the master device 20 is invalid.

When the control unit 511 of the output unit 51b receives from the communication unit 10A a notification that the state has transitioned to the SafeOP state, it reads the load shedding data stored in the memory unit 512 and outputs the value to the external output device 71b. The control unit 511 determines the load shedding data according to the settings shown in Tables 1 and 2 and outputs the value to the external output device 71b.

Furthermore, output unit 51d does not have a control unit 511 or a memory unit 512 like output unit 51b. In this case, communication unit 10A notifies output unit 51d that it has transitioned to the SafeOP state, and notifies output unit 51d of the load shedding data stored in a memory unit (not shown). When output unit 51d receives notification from communication unit 10A that it has transitioned to the SafeOP state, it receives the load shedding data from communication unit 10A and outputs the value to external output device 71d.

Also, if the upper communication mode received last time is the same as the upper communication mode received this time (S3, same as last time), the control unit 121 does not perform any particular processing (S5) and the process proceeds to step S7.

Furthermore, if the previously received upper communication mode was Idle and the currently received upper communication mode is Run (S3, Idle to Run), the control unit 141 transitions the IO units 51a to 51d belonging to the remote IO system group 70 to OP state (S6), and processing proceeds to step S7.

In step S7, the control unit 141 saves the currently received upper communication mode (S7), returns to step S1, and repeats the subsequent processes. Note that steps S1 to S7 are performed periodically, with the cycle being predetermined.

§4 Functions and Effects According to the embodiment of the present invention, when the control unit 141 receives an upper communication mode in the Idle state from the master device 20 via the first communication unit 13, the control unit 511 reads out the setting data stored in the storage unit 512 and sets it in the output unit 51b. Therefore, the output unit 51b can cut off the output, preventing the external output device 71b from malfunctioning or entering an unexpected state, and ensuring safety.

Furthermore, when the upper communication mode is in the Idle state, the control unit 141 reads the load shedding data stored in the memory unit and sets the load shedding data corresponding to each of the output units 51b and 51d. Therefore, appropriate setting data can be set for each of the output units 51b and 51d.

Furthermore, even if the standalone system is unable to receive instructions from the master device 20 via the first communication unit 13, it will control the output units 41b and 41d independently. Therefore, there is no need for configuration data corresponding to the output units 41b and 41d.

[Software implementation example]
The functional blocks of the communication unit 10A (particularly, the control unit 141) may be realized by a logic circuit (hardware) formed on an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the communication unit 10A includes a computer that executes program instructions, which are software that realizes each function. This computer includes, for example, one or more processors and a computer-readable recording medium that stores the program. The object of the present invention is achieved when the processor in the computer reads and executes the program from the recording medium.

The processor may be, for example, a CPU (Central Processing Unit). The recording medium may be a "non-transitory tangible medium," such as a ROM (Read Only Memory), tape, disk, card, semiconductor memory, or programmable logic circuit. The computer may also include a RAM for expanding the program. The program may be supplied to the computer via any transmission medium capable of transmitting the program (such as a communications network or broadcast waves). One aspect of the present invention may also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments and examples, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments and examples are also included within the technical scope of the present invention.

REFERENCE SIGNS LIST 1 Network system 10 Communication gateway device 10A Communication unit 11 Unit belonging to stand-alone system 12 Unit belonging to remote IO system 13 First communication unit 14 Second communication unit 20 Master device 30 Hub device 41a, 41c, 51a, 51c Input unit 41b, 41d, 51b, 51d Output unit 60 Stand-alone system group 61a, 61c, 71a, 71c External input device 61b, 61d, 71b, 71d External output device 70 Remote IO system group 141, 511 Control unit 142 Local bus communication unit 512 Storage unit

Claims (5)

a first communication unit that communicates with a master device via a network;
a second communication unit that communicates with the output unit via the local bus;
a control unit that, when receiving a notification from the master device via the first communication unit that the master device is in an idle state in which it is not issuing instructions , controls the second communication unit to notify the output unit that output data received from the master device and to be transmitted to the output unit is invalid. the communication unit further includes a storage unit configured to store load shedding data corresponding to the output unit;
2. The communication unit according to claim 1, wherein the control unit controls the second communication unit to notify the output unit of the load shedding data stored in the memory unit when the control unit is unable to receive instructions from the master device via the first communication unit. A network system including a master device and a communication unit,
The communication unit includes a first communication section that communicates with the master device via a network;
a second communication unit that communicates with the output unit via the local bus;
a control unit that, when receiving a notification from the master device via the first communication unit that the master device is in an idle state in which it is not issuing instructions , controls the second communication unit to notify the output unit that output data received from the master device and to be transmitted to the output unit is invalid. 1. A computer-implemented method for controlling an output unit, comprising:
receiving a notification from the master device that the master device is in an idle state in which the master device is not issuing instructions;
and when receiving the notification from the master device, notifying the output unit that the output data received from the master device and to be output to the output unit is invalid. A computer program for causing a computer to execute a control method for an output unit,
The control method includes the steps of: receiving a notification from the master device that the master device is in an idle state in which the master device does not issue instructions;
and notifying the output unit, upon receiving the notification from the master device, that the output data received from the master device and to be output to the output unit is invalid.