KR20130058359A - Apparatus and method for network based control - Google Patents

Abstract

PURPOSE: A network based controller and a method thereof are provided to minimize time delay and to improve the performance of a system. CONSTITUTION: A network based controller connects at least one lower layer device to each network and forms two or more networks(31a,31b). A method to connect lower layer devices to a network is classified by the type of the lower layer device or operational characteristics, and a communication cycle of an upper layer device which communicates with the lower layer devices through each network is differently set according to the network. Lower layer devices connected to a first network and the lower layer devices connected to a second network are connected in a daisy chain method. [Reference numerals] (31) Upper layer device; (31a) First network; (31b) Second network; (33-1,33-2,33-3,35-1,35-2,35-3) Lower layer device

Description

Network-based control device and method thereof {Apparatus and Method for Network Based Control}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network-based control device and method thereof, and more particularly, to various types of sub-devices connected through a network such as a servo drive, an inverter, an input / output (I / O) device, a high speed counter, a vision sensor, and the like, such as a motion controller. The upper device controlling the control unit performs communication according to the communication cycle suitable for the operation characteristics of each lower device, so that more rapid and efficient control can be achieved.

A system having a structure in which an upper device (master device) is connected to various types of lower devices (slave devices) through a network to collect information and control the lower device based on the collected information is used in various fields.

For example, a motion controller that controls the movement of various devices or systems plays the role of a host device, and is connected to a subordinate device such as a servo drive, an inverter, an I / O device, a high speed counter, and a vision sensor through a network.

It communicates with the subordinate devices according to a certain communication cycle and controls each subordinate device and updates data.

In a system of such a structure, the conventional host device controls the subordinate devices through a single network, so that the communication period for communicating with the subordinate devices is always constant regardless of the type or operation characteristics of the subordinate devices.

For example, the communication cycle with sub devices that need to access data at high speed such as I / O devices or high-speed counters is the same as the communication period with sub devices that have relatively long data processing times such as servo drives or vision sensors. Falls.

With reference to Figures 1 and 2 will be described in detail the conventional problem.

1 illustrates a servo drive 13, an I / O device 14, a high speed counter 15, and a camera 12-4 in which a motion controller 11 serving as a host device controls a motor 12-1. ) Shows the state connected with the sub-device such as the vision sensor 16 to control.

In general, the lower devices have a communication port connected to the upper device or the previous lower device and a communication port connected to the next lower device.

The communication port of the servo drive 13, which is the first subordinate device, is connected to the communication port of the motion controller 11, and the next servo drive, I / O device, high-speed counter, and vision sensor are daisy-chained. Etc. are connected.

2 illustrates an operation timing related to the control of a subordinate device of a motion controller, and the motion controller 11 performs control on the subordinate devices according to a predetermined control period. Replace it.

The control period 20 is generally determined as a multiple of the communication period 21, and an example in which the control period 20 and the communication period 21 are the same is illustrated in FIG. 2.

The main function of the motion controller 11 is to receive an input signal from the lower devices through the network, perform a control operation internally, and then deliver the output signal to the output device. In this process, the motion controller 11 performs network processing 24 at the beginning of the control cycle, and the network processing is performed according to the communication cycle.

For example, data is read from the I / O device 14 in each communication cycle, and the input signal 18 or the output signal is processed in the corresponding control cycle (22-1, 23-1). The output signal processed by the motion controller 11 is transmitted to and reflected by the corresponding lower device 14 when performing the network processing function of the next communication period (19).

Conventionally, since only one network 11a is used and the communication period 21 is determined on the basis of the longest operation device, an unnecessary time delay occurs to receive an input signal and output an output signal.

That is, even when the input signal 18 is turned on at the time A, since network processing has already been completed, at the time B when the motion controller 11 processes the input signal, this state cannot be recognized and cannot be processed. In the network processing at the time point, the corresponding input signal 18 is taken and input processing at the time D point (22-2), and then output processing 23-2.

In addition, even if the corresponding output signal is turned ON in the output processing 23-2, the output signal is not immediately reflected on the output of the I / O device 14, and this output signal is the I / O at the next network processing point E. Is sent to the device 14 and reflected at the time point F.

As described above, a time delay 25 occurs when the motion controller 11 receives an input signal from the lower devices and sends an output signal to the output device. Particularly, the motion controller 11 receives the input signals from the lower devices. When the communication cycle is determined, inefficiency due to unnecessary time delay is more highlighted because data processing for lower devices with relatively short operation time is affected.

In addition, the input signal G which changes in the communication period 21 is not detected. However, the longer the communication period 21, the greater the problem.

Accordingly, the present invention has been made to solve the above problems, the process of receiving the input signal from the lower device connected to the network and processing the output signal to the output device is further processed according to the operation characteristics of the lower device The goal is to make it happen quickly and efficiently.

In order to achieve the above object, the network-based control device according to the present invention forms at least two networks that communicate separately in correspondence with at least two groups of sub-devices, and each of the sub-devices connected through each network; The communication cycle for communicating is configured to be set differently for each network.

The communication period for each network may be set as a multiple of the basic communication period, and the basic communication period may be the shortest communication period among the communication periods set for each network.

The network-based control device may perform synchronization of transmission of control commands to a lower device.

One method for the synchronization is to transmit the control command according to the longest communication period among the communication periods set for each network.

The network-based control method according to the present invention is a method for controlling a lower device while the upper device capable of forming at least two networks communicates with a lower device connected to each network according to a preset communication period.

Setting a communication period for each of the networks; And controlling the lower device while communicating with the lower device connected to each network according to the set communication period, and the communication period for each network is set differently according to the type of the lower device connected to the corresponding network.

Since the network-based control apparatus according to the present invention can form a plurality of networks, it can be connected separately through a network separated from other sub-device groups having different operating characteristics.

Accordingly, the communication cycle for each network can be set separately so that the data of the lower devices that need to access the data at high speed can be processed quickly and the performance of the system can be improved by minimizing unnecessary time delays.

For example, it is possible to shorten the data update time of the lower devices that need to recognize and process the state more quickly, such as I / O devices or high-speed counters.

Since the communication period set for each network can be arbitrarily determined, it is easy to implement synchronization to control the subordinate devices at the same time point as the subordinate devices are connected through one network.

In this regard, a communication cycle set for each network may be configured to be a multiple of each other, and an input signal received according to a short communication cycle may be output by synchronizing and outputting an event after processing an event.

In addition, when the communication period with the lower devices is shortened, the problem of not recognizing the input signal changing in the communication period can be reduced.

If the network-based control device according to the present invention is implemented using an improved means for network connection such as a central processing unit (CPU) in which a plurality of Ethernet controllers are built, the burden due to a plurality of network processing can be minimized.

1 is a conventional structure in which a motion controller and sub devices are connected;
2 is an operation timing associated with controlling a sub-device of a motion controller,
3 is an embodiment of a network-based control device according to the present invention;
4 is a structure in which a motion controller and sub devices are connected according to the present invention;
5 is an example of configuration of a network-based control device according to the present invention;
6 is an operation timing for controlling sub-devices according to the present invention;
7 is an embodiment of a network-based control method according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 3, the network-based control device 31 (hereinafter, referred to as an upper device) according to the present invention forms at least two or more networks 31a and 31b, and one or more subordinate devices are connected to each network. .

Which subordinate device is connected to which network may be classified according to the type or operation characteristics of the subordinate device, and a communication cycle in which the upper device 31 communicates with the subordinate device connected through each network is set differently for each network.

Sub-devices to be connected to each network may be classified according to the time that communication with the host device 31 is to be made.

In this case, the communication period of the network to which the lower device to which communication with the upper device 31 is to be quickly connected may be set to be shorter than the communication period of the network to which the lower device to which the upper device 31 is connected later.

3, the lower devices 331-˜ 33-3 connected to the first network 31 a and the lower devices 35-1 ˜ 35-3 connected to the second network 31 b are connected in a daisy chain manner. Although showing an example, the connection structure between the upper and lower devices may be configured in various ways as necessary.

4 shows an example in which a motion controller 41 serving as an upper device 31 is connected to each lower device through two networks 31a and 31b.

The motion controller 41 may transmit / receive data by connecting each subordinate device to a high speed fieldbus network, and may be configured in various forms such as PC (Personal Computer), PLC (Programmable Logic Controller), or standalone. Can be.

A servo drive 13 for controlling the motor 12-1 and a vision sensor 16 for controlling the camera 12-4 are connected to the first network 31 a as a subordinate device. 31b), the I / O device 14 and the high speed counter 15 are connected as a subordinate device.

Here, it is assumed that lower devices connected to the second network 31b should communicate with the motion controller 41 faster than lower devices connected to the first network 31a. That is, the servo drive 13 or the vision sensor 16 connected to the first network 31a is a subordinate device having a long control cycle in the motion controller 41 due to the large amount of data to be processed, and the second network 31b. The I / O device 14 and the high-speed counter 15, which are connected to the I / O device 14, are simple functions of low-level devices that have a relatively short control period in the motion controller 41 because the data to be processed is small.

Since the motion controller 41 forms two networks, two network controllers are required. In recent years, an industrial Ethernet-based fieldbus network (eg EtherCAT) is widely used, and a central processing unit (CPU) with a plurality of Ethernet controllers is built in. : Central Processing Unit is released, so you can easily configure network by connecting only communication port.

FIG. 5 shows an example of a motion controller 41 employing an Ethernet-based fieldbus network, and includes a central processing unit 41-1 and a CPU having two Ethernet controllers ECON-1 and ECON-2. The first network 31a and the second network 31b may be formed through the physical layers PHY-1 and PHY-2 and the communication ports 41-3 and 41-4, respectively.

This hardware configuration has the advantage of reducing the network processing time that is increased by using two networks.

In general, the communication period of each network may be determined according to the control period and the number of the connected lower devices.

For example, the servo drive 13 or the vision sensor 16 may operate according to a communication cycle of 1 ms, and the I / O device 14 or the high speed counter 15 may communicate several tens of μs in a recent fieldbus network. Periodically, data can be updated sufficiently.

FIG. 6 illustrates operation timings associated with subordinate device control of the motion controller illustrated in FIG. 4.

Since the second communication period 63 for the second network 31b is set to be shorter than the first communication period 62 for the first network 1 31a, the sub-devices connected to the second network 31b may be selected. Faster update is possible compared to the lower devices connected to one network 31a.

The communication period and the control period can be set in various ways as necessary, the control period 60 is usually determined as a multiple of the communication period (62, 63). In FIG. 6, it is assumed that the control period 60 of the motion controller 41 is the same as the first communication period 62 for the first network 31a for convenience of description.

The motion controller 41 communicates with the subordinate devices 13 and 16 connected to the first network 31a according to the first communication period 62 and with the subordinate devices 14 and 15 connected to the second network 31b. Communicate in accordance with the second communication cycle (63).

The actual communication takes place at the beginning of the communication cycle 64-1, 64-2. For example, when the input signal 18 of the I / O device 14 is ON at time a, the motion controller 41 may recognize this situation through communication through the second network 31b at time b. And the output of the I / O device 14 can be turned ON at time c of the control period 68. This setting data is transferred to the I / O device 14 at time d of the next communication cycle through the second network 31b, and at time e, the output signal 19 of the I / O device 14 is turned ON. ) do.

As a result, the delay time 65 after detecting the input signal from the I / O device 14 and before the output signal is reflected in the I / O device 14 is reduced than the corresponding delay time 25 in FIG. The delay time 25 of 2 can be reduced by up to n times, and the length of the detectable input signal can be improved by n times. n is a ratio of the first communication period 62 and the second communication period 63.

This effect is to configure each network separately according to the operation characteristics of the lower devices, the second communication period 63 for the second network 31b is shorter than the first communication period 62 for the first network 31a. Appears because you can set.

On the other hand, the communication period corresponding to each network may be set as a multiple of the basic communication period with respect to the synchronization in the motion controller 41 controls the lower devices. In this case, the shortest communication period among communication periods for each network may be used as the basic communication period.

In FIG. 6, the second communication period 63 is set to 1 / n (n is an integer) of the first communication period 62, and if the first communication period 62 is 1 ms, the second communication period 63 is It can be 200 μs, which is 1/5. In this case, five times communication with the lower devices connected to the second network 31b is performed while the lower devices connected to the first network 31a are once communicated.

If the motion controller 41 processes the point of time at which the control commands are collectively synchronized for each sub-device as "n x 2nd communication period", even if the motion controller 41 has two networks, it is always constant. The sub-devices can be controlled at this point in time, thereby giving synchronization to the control equipment application.

In addition, if the motion controller 41 wants to transmit a control command at a specific time point, the control command may be processed in the next control period, so that the input signal 18 of the I / O device 14 recognized through the communication at time point b is obtained. ) Can be registered and processed as an event at time c.

Here, event processing means executing a program that performs a specific function when a specific condition such as a rising edge of an input signal occurs.

An embodiment of a network-based control method according to the present invention will be described with reference to FIG. 7.

First, an upper device is a device capable of forming at least two or more networks, and connects one or more lower devices to each network of the upper device (S71). In this case, the connection structure between the upper device and the lower device may be variously configured as necessary.

And a communication cycle for each network is set (S72).

The communication period means a time interval in which the upper device and the lower device communicate with each other, and the communication period for each network may be set according to the type or operation characteristics of the lower device connected to the corresponding network.

That is, the communication period in which the upper device communicates with the lower device connected through each network is set differently for each network. The communication period of the network to which the lower device to which communication with the upper device should be quickly connected is set to be shorter than the communication period of the network to which the lower device to which the upper device is connected later.

Now, the upper device controls the lower device while communicating with the lower device connected to each network according to the communication period set through step S72 (S73).

The method of controlling the lower device while the upper device communicates with the lower device can be variously configured as necessary.

For example, the host device communicates with the subordinate device according to the communication cycle, reads data from the subordinate device, passes control output to achieve the desired purpose based on the input data, and delivers the output data to the subordinate device. Sub-devices can be controlled via

Referring to FIG. 4, the motion controller 41 communicates with the lower devices connected to the first network 31a every first communication period 62, and the second communication with the lower devices connected to the second network 31b. Communication is performed every period 63, and actual communication takes place at the beginning 64-1, 64-2 of each communication period 62, 63.

An example of a process (S73) in which the control of the lower devices connected to the second network 31 b is performed will be described.

When the input signal 18 of the I / O device 14 is ON at time a, the motion controller 41 can recognize this situation through communication through the second network 31b at time b. The output of the I / O device 14 is set to be ON at time c of the control period 68. This setting data is transferred to the I / O device 14 at time d of the next communication cycle through the second network 31b, and at time e, the output signal 19 of the I / O device 14 is turned ON. ) do.

As a result, the delay time 65 after detecting the input signal from the I / O device 14 and before the output signal is reflected in the I / O device 14 is reduced than the corresponding delay time 25 in FIG. The delay time 25 of 2 can be reduced by up to n times, and the length of the detectable input signal can be improved by n times.

On the other hand, the motion controller 41 may set the communication period corresponding to each network as a multiple of the basic communication period in step S72 with respect to the synchronization in the motion controller 41 controls the lower devices.

In this case, the shortest communication period among communication periods for each network may be used as the basic communication period.

In the example shown in FIG. 6, the second communication period 63 is set to 1 / n (n is an integer) of the first communication period 62, and if the first communication period 62 is 1 ms, the second communication period ( 63) may be 200 μs that is 1/5 of that. In this case, five times communication with the lower devices connected to the second network 31b is performed while the lower devices connected to the first network 31a are once communicated.

In step S73, if the motion controller 41 transmits the control commands collectively synchronized to each subordinate device and processes the time point as "n x 2nd communication period", even if it has two networks, it is always at a certain time point. The sub-devices can be controlled, giving synchronization to the control equipment application.

In addition, if the motion controller 41 wants to transmit a control command at a specific time point, the control command may be processed in the next control period, so that the input signal 18 of the I / O device 14 recognized through the communication at time point b is obtained. ) Can be registered and processed as an event at time c.

It is to be understood that the present invention is not limited to the above-described embodiment, and that various changes and modifications may be made by those skilled in the art without departing from the technical spirit of the present invention. to be.

11, 41: Motion Controller 13: Servo Drive
14: I / O Device 15: High Speed Counter
16: Vision Sensor 31: Host
31a: first network 31b: second network
33-1 to 33-3, 35-1 to 35-3: Subunit 41-1: Central Processing Unit (CPU)
41-3,41-4: Communication port
ECON-1, ECON-2: Ethernet Controller PHY-1, PHY-2: Physical Layer

Claims (10)

In the network-based control device for controlling the sub-device while communicating with a plurality of sub-devices connected via a network according to a predetermined communication period,
Form two or more networks that communicate with each other at least two groups of sub-devices separately,
Communication period for communicating with the sub-devices connected through each network is a network-based control device, characterized in that is set differently for each network. The method of claim 1,
The communication period for each network is a network-based control device, characterized in that set in multiples of the basic communication period. 3. The method of claim 2,
The basic communication period is a network-based control device, characterized in that the shortest communication period of the communication period set for each network. The method of claim 1,
Transmission of the control command to the lower device is a network based control device, characterized in that the synchronization. The method of claim 4, wherein
The synchronization is a network-based control device, characterized in that by transmitting the control command in accordance with the longest communication period of the communication period set for each network. In the network-based control method for controlling the lower device while the upper device capable of forming at least two networks communicate with the lower device connected to each network according to a predetermined communication period,
Setting a communication period for each of the networks; And
And controlling the lower device while communicating with the lower device connected to each network according to the set communication period.
The communication cycle for each network is set differently according to the type of the lower device connected to the network. The method according to claim 6,
The communication period for each network is a network-based control method, characterized in that the set in multiples of the basic communication period. The method according to claim 6,
The basic communication period is a network-based control method, characterized in that the shortest communication period of the communication period set for each network. The method according to claim 6,
The control method based on the network, characterized in that the transmission of the control command to the lower device is synchronized. The method of claim 9,
The synchronization is a network-based control method characterized in that by transmitting the control command according to the longest communication period of the communication period set for each network.

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