KR20180031573A - Powerlink Wireless HART gateway for industrial automation - Google Patents

Abstract

The present invention relates to a method for integrating a wirelessHART network into an Ethernet powerlink backbone. In the field of industry automation, a function of a smart wireless device to be perfectly connected to a real-time Ethernet-based industry backbone having determinacy of high bandwidth becomes an important issue of the study. According to the method for integrating a wirelessHART network into an Ethernet powerlink backbone, a Linux-based open powerlink-wirelessHART gateway (PW-GW) solution is provided. The difference between a powerlink protocol and a wirelessHART protocol can be solved when an application layer transformation method according to the present invention is implemented in the PW-GW. In addition, according to the present invention, an experimental system for developing a prototype of the PW-GW solution and verifying functions and performance thereof is constructed to measure a communications delay of the system, thereby verifying whether the PW-GW of the present invention satisfies real-time requirements of time-sensitive industrial applications.

Description

Powerlink Wireless HART Gateway for Industrial Automation {Powerlink Wireless HART gateway for industrial automation}

The present invention relates to a power link wireless HART gateway (PW-GW) connecting a wireless HART (WirelessHART) system and a Powerlink system.

In industrial automation systems, wireless technology increases process insight, reduces installation and cabling costs, supports portability and rapid deployment, and improves the overall operational performance of industrial plants. Industrial wireless sensors detect plug lines, burner flame instability, agitator losses, wet gas, orifice wear, leaks, and cavitation to alert the user how well the system works and when maintenance is required.

This trend of industrial automation that has emerged in recent years will lead to greater demand for smart radio devices. At the same time, many industrial communications backbone relies on wired communications to exchange process information between the plant network, the control network, and the field network. Therefore, it will be important to seamlessly connect these smart radio functions to the latest high-bandwidth and deterministic real-time Ethernet-based backbone infrastructures.

Industry wireless standards such as wireless HART (WirelessHART), ISA100.11a, and wireless networks for industrial automation and process automation (WIA-PA) support the use of wireless monitoring and control solutions in harsh industrial environments .

Previous studies have compared the performance of wireless HART and ZigBee standards, and the results show that ZigBee standards are not suitable for industrial environments due to performance degradation. In addition, other prior studies have addressed the problems raised when integrating wireless HART devices in automation systems and proposed a framework approach to integrate wireless HART components into industrial host applications. However, their research was a conceptual approach without methods or implementation schemes. Methods for integrating wireless HART and legacy HART networks have been disclosed heretofore. The prior art presented an option for integrating wireless HART into PROFIBUS using mapping technology. However, using legacy HART or PROFIBUS as an industrial backbone provides relatively low real-time performance compared to real-time Ethernet-based fieldbus in the latest smart manufacturing scenarios.

PROFINET, Powerlink, EtherNet / IP, EtherCAT and SERCOS III (five of about 30 industrial Ethernet-based systems) are gaining popularity due to technical performance, standardization status and strategic market considerations. The first integration test of the wireless HART network and PROFINET was described in previous IEEE conferences. However, this suggests a design proposal without details of actual implementation. A related study developed this to implement the integration of a wireless HART network in a distributed control system using PROFINET IO. However, the results did not show the real-time performance of the system.

Table 1 compares the five most common industrial Ethernet standards. Table 1 shows that the Ethernet Powerlink is emerging as an excellent technology because of the free open source code of the protocol stack, the lowest hardware cost, high availability and high real-time performance. Therefore, the integration of the wireless HART system with the power link backbone is an important area for further investigation.

U.S. Patent No. 8,203,980

It is an object of the present invention to meet the end user expectations of the industry that there should be no difference between the protocols when the industrial automation network accesses the wireless network sensor system.

It is also an object of the present invention to integrate the wireless HART network into the Ethernet power link backbone by reducing the difference between the power link protocol and the wireless HART protocol.

To this end, the integrated power link wireless HART system according to the present invention comprises a power link management node (MN) for controlling industrial equipment connected to the Ethernet power link, a plurality of wireless HART devices (mote) And a Power Link Wireless HART Gateway (PW-GW) connected to the Ethernet Power Link to perform protocol conversion between the power link management node and the plurality of wireless HART devices between the power link protocol and the wireless HART protocol.

In addition, the power link wireless HART gateway according to the present invention includes a parser for receiving and parsing information of a plurality of wireless HART devices existing on a wireless HART network, a wireless HART command received from the power link management node, And a memory for storing information of each wireless HART device parsed by the parsing unit in a power link object dictionary.

The power link wireless HART integration method according to the present invention further includes the steps of the power link management node transmitting the wireless HART command to the power link wireless HART gateway, and the wireless HART gateway transmitting the wireless HART command to the power link object dictionary Wherein the wireless HART gateway configures a wireless HART network by a wireless HART command recorded in the power link object dictionary and communicates with a plurality of wireless HART devices to record information from the plurality of wireless HART devices Parsing the information of each wireless HART device collected by the wireless HART gateway and individually recording the information in the power link object dictionary; and transmitting the power link object dictionary to the power link object dictionary OD) from each of the wireless HART devices.

The power link wireless HART integration method according to the present invention further includes the steps of receiving a wireless HART command from a power link management node and recording the wireless HART command in a power link object dictionary, Collecting information from the plurality of wireless HART devices by communicating with a plurality of wireless HART devices, parsing the information of the collected wireless HART devices, and storing the parsed information in the power link object dictionary .

The power link wireless HART integration method according to the present invention further includes the steps of receiving a wireless HART command from a power link management node and recording the wireless HART command in a power link object dictionary, Receiving and parsing information of a plurality of wireless HART devices existing on a wireless HART network from the wireless HART manager, and transmitting information of each parsed wireless HART device to a power link object dictionary And recording.

As described above, when the application layer conversion method is implemented in the gateway (PW-GW) according to the present invention, the difference between the power link protocol and the wireless HART protocol can be solved.

In addition, the present invention develops a prototype of the PW-GW solution, builds an experimental system capable of verifying the function and performance, and measures the communication delay of the system, so that the PW-GW according to the present invention is real- You can verify that you meet the requirements.

This will enable PW-GW and wireless HART field devices (FDs) to be deployed in smart factories with legacy Ethernet power link systems to increase process insight, reduce cable and installation costs, and improve the overall operational performance of industrial facilities. .

1 is a configuration diagram of an integrated power link wireless HART system according to the present invention;
2 is a hardware block diagram of a power link wireless HART gateway (PW-GW) according to the present invention;
3 is an actual photograph of a gateway (PW-GW) according to the present invention.
4 is a software configuration diagram of a gateway (PW-GW) according to the present invention;
5 shows a cycle of a power link according to the invention;
6 shows a super frame of a wireless HART according to the present invention.
7 illustrates an application layer transformation method according to the present invention.
8 is a configuration diagram of a gateway experimental system for a gateway (PW-GW) experiment according to the present invention.
FIG. 9 is a photograph of a real system of a gateway (PW-GW) experimental system according to the present invention.
10 is a diagram showing a communication delay between the power link MN and the gateway (PW-GW);
11 is a diagram illustrating a communication delay between a wireless HART manager and a wireless HART device;

The present invention provides a Linux-based open Power Link-Wireless HART Gateway (PW-GW). The purpose of the PW-GW in accordance with the present invention is to meet the expectations of the end user of the industry that there should be no difference when accessing devices for the wired and wireless industries. The present invention considers low development cost, open solutions and real-time performance. Conventionally, there is no protocol conversion method between a power link and a wireless HART. However, the present invention proposes an application layer protocol conversion method for reducing a difference between a power link protocol and a wireless HART protocol. PW-GW hardware and software have been developed and experimental systems have been established to demonstrate their functionality and performance. The communication delay of the system is measured to ensure that the PW-GW according to the present invention meets real-time requirements in time-sensitive industrial applications.

1 shows an integrated power link wireless HART system according to the present invention.

The Ethernet power link network 20 operates as an industrial backbone due to its high bandwidth and deterministic real-time characteristics. The power link network 20 is comprised of power link managing nodes (MN) 10 and powerlink controlled nodes (CN) 30. The production process application (host application) is executed in the power link management node 10.

The controlled node (CN) 30 is composed of a power link PLC 31 connected to the Ethernet power link network 20 and an industrial equipment 33 connected to the power link PLC 31. The industrial equipment 33 includes a manipulator and a motor. The power link PLC 31 and the gateway (PW-GW) 40 according to the present invention are controlled by the power link MN 10 and in the present invention the power link PLC 31 and the PW- And belong to the set of link controlled nodes.

The PW-GW 40 includes a protocol conversion unit 41 and a wireless HART management unit 43. (PW-GW) 40 according to the present invention when the protocol conversion unit 41 and the wireless HART management unit 43 are incorporated in one package. However, when the wireless HART management unit 43 receives the wireless HART The protocol converting unit 41 constitutes a gateway PW-GW according to the present invention and the wireless HART managing unit 43 constitutes a separate It can be a wireless HART manager.

Hereinafter, a description will be given assuming that the protocol conversion unit 41 and the wireless HART management unit 43 are integrated with each other, and the wireless HART management unit and the wireless HART manager are mixed.

Wireless HART networks improve flexibility and reduce installation and maintenance costs. A typical wireless HART network consists of a network manager (NM), a security manager (SM), and an access point (AP), which are usually contained in a single box. This box is referred to as the wireless HART manager 43. In addition to these components, the wireless HART network has other components such as a field device (FD) 50, and the field device performs basic functions of sensing and operation in an industrial facility. The PW-GW 40 according to the present invention can connect thousands of wireless HART FDs 50 to the power link backbone network 20 throughout the industrial process. In this way, you can take advantage of the flexibility of the wireless HART network as well as the high bandwidth of the deterministic real-time power link backbone.

FIG. 2 shows a hardware configuration of the PW-GW gateway according to the present invention, and FIG. 3 shows an actual photograph of the PW-GW.

As shown in FIG. 2, the PW-GW gateway 40 is connected to the Ethernet power link network 20 and includes a protocol conversion unit 41 and a wireless HART management unit 43.

In the protocol conversion unit 41, a power link protocol stack and an application layer translation according to the present invention are performed. This application layer translation is executed in the AM3358 ARM Cortex-A8 microprocessor (MCU) in the Linux operating system, while the wireless HART protocol stack is executed in the wireless HART management unit 43. [ It also employs an online SmartMesh wireless HART manager solution.

Gateway software

Figure 4 shows the PW-GW software architecture.

The PW-GW software consists of a power link protocol stack, a wireless HART protocol stack, and an application layer translation method according to the present invention.

1) Power Link Protocol

In the OSI model, the power link protocol specifies a physical layer, a data link layer, and an application layer, as shown in FIG. The power link network access is managed by a dedicated node called a management node (MN). The MN can manage up to 239 controlled nodes (CN).

In the Power Link protocol, the Ethernet standard is extended with an additional bus scheduling mechanism. As shown in FIG. 5, the bus scheduling mechanism classifies time slots into an isochronous phase and an asynchronous phase. The power link cycle consists of one isochronous phase (phase) and one asynchronous phase (phase).

During the isochronous phase, the MN sends a start of cycle (SoC) frame to indicate the start of isochronous communication. This will synchronize all network stations. The MN then sends a Poll Request (PReq) frame with a time-critical payload (control signal) to each CN, and each CN sends real-time data (process data) to PReq, And transmits a Poll Response (PRes) frame together with the frame. During this phase, the data transmission time of each node is deterministic. Data transfer during this phase is called process data object (PDO) transfer.

During the asynchronous phase, the MN sends an Asynchronous Start (SoA) frame to indicate the start of asynchronous communication and to assign authority to a particular node (MN or CN) for asynchronous communication. An addressed node responds with an asynchronous transfer (ASnd) frame that transmits asynchronous data. The MN manages the scheduling of all asynchronous data transmissions. If the CN is to transmit an asynchronous frame, it notifies the MN via PRes. The asynchronous scheduler of the MN determines which node is authorized to transmit the asynchronous frame in accordance with the priority of the queue. Therefore, the data transmission at this stage is not deterministic, and is referred to as a Service Data Object (SDO) transmission.

Power link cycle times depend on industrial applications. Cycle times up to hundreds of milliseconds are sufficient for flexible real-time applications, such as temperature monitoring, and motion control applications require less than 1 millisecond cycle time. The bus scheduling mechanism guarantees deterministic communication by allowing only one determined node in a fixed time slot to access the network.

2) Wireless HART protocol

In the wireless HART protocol, the physical and MAC layers are based on the IEEE 802.15.4 standard operating in the 2.4 GHz ISM band (see FIG. 4). The network supports mesh topology. Other topologies can occur dynamically and depend on characteristics such as distance between nodes, number of devices, and so on. Wireless HART is a self-healing network and includes features such as channel hopping for each transmission and various routing mechanisms to improve stability. Wireless HART uses TDMA to control network access, providing conflicting, deterministic communications. The time of the network is composed of time slots, and the communication between wireless HART nodes is performed in the time slot. As shown in FIG. 6, this time slot constitutes a TDMA super frame. All these attributes provide high flexibility, security, reliability and determinism in poor industrial environments.

Application layer transformation method

The wireless HART application layer defines various commands and responses. Communication between the wireless HART device and the gateway is based on commands and responses. The application layer parses the message contents, extracts the command number, executes the specified command, and generates a response. The wireless HART manager uses application layer commands to configure and manage the entire wireless HART network. The present invention employs a SmartMesh wireless HART manager solution pioneered by Linear's Dust Networks group. The Smart Mesh Wireless HART Manager acts as a server that provides an interface between the gateway and the wireless HART network. This interface is called Smart Mesh Wireless HART Manager Command Application Programming Interface (API). As shown in FIG. 4, the application layer conversion method according to the present invention continues the gap between the smart mesh wireless HART manager command API and the power link application layer.

The PowerLink application layer employs an object-oriented CANopen protocol. A key element of this protocol is the Object Dictionary (OD). The OD is a structured list of CANopen-type objects that contain all the parameters that correspond to the communication stack (eg, node configuration) and process variables transferred between the MN and the CN. Each object, i. E., A parameter or process variable, has a unique hexadecimal numeric identifier (index). The power link OD structure is shown in Table 2.

PowerLink developers can freely define objects in the range 0x2000 to 0x5FFF (manufacturer unique profile area). The present invention defines a new power link object for use with PW-GW as Table 3.

7 illustrates an application layer conversion method according to the present invention.

7, the protocol conversion unit 41 includes a parsing unit 41-1 for parsing the response input from the wireless HART manager 43 and a memory 41-2 for storing the power link OD ).

First, using the power link OD, the host application (power link MN) 10 writes the wireless HART command to the memory 41-2 of the PW-GW OD (0x2000 / 0x01) via the power link PDO transmission (1) do. This command is immediately sent to the wireless HART manager 43 to configure, monitor and execute the wireless HART network. The wireless HART manager 43 configures the wireless HART network and communicates with the wireless HART device (mote) 50. The wireless HART manager 43 collects information from the wireless HART device 50 and sends a response to the PW-GW. The command and response formats are defined in the Smart Mesh Wireless HART Manager API Guide. The PW-GW parses the response via the parsing unit 41-1 and stores the information of the wireless HART device individually in the corresponding power link object of the memory 41-1 as defined in Table 3. [ The host application (Powerlink MN) 10 periodically reads the PW-GW OD (0x2001-0x20nn) of the memory 41-2 through the power link PDO transfer (2) to transfer the device information from the wireless HART device 50 .

Gateway experiment

A gateway experimental system is shown in Figures 8 and 9. In this system, the host application (Powerlink MN) is installed on a PC running the Linux OS. A prototype of the PW-GW that connects the wireless HART network to the Ethernet power link backbone was designed and implemented. Five wireless HART devices were provided in the Smart Mesh Wireless HART solution.

The gateway functional test was designed to verify the functionality of the PW-GW.

First, the host application (Powerlink MN) sends "getMotes" (wireless HART manager command) to the PW-GW via the Ethernet power link backbone. The "getMotes" command requests that the wireless HART manager collect information from all wireless HART devices. The PW-GW sends this command to the wireless HART manager. When this command is executed, the wireless HART manager sends a response containing all the information from the wireless HART device to the PW-GW. The PW-GW parses the response message and stores the information of each wireless HART device separately in the corresponding power link object defined in Table 3. Through the power link PDO transmission, the host application (Powerlink MN) obtains information from the wireless HART device by periodically reading the PW-GW OD (0x2001-0x20nn).

Table 4 shows some of the test results read by the host application (Powerlink MN).

"Good neighbors" means the number of adjacent devices with good quality (more than 50%) paths. For Mote # 1, there are five devices with good quality paths, including four different wireless HART devices (mote) and one AP in the PW-GW. "Voltage" refers to the voltage read from the last measurement of the power supply of the wireless HART device (mote).

Communication over the entire system can be divided into communication between the power link MN and the PW-GW, and communication between the wireless HART manager and the wireless HART device (mote). The PW-GW's MCU clock speed reaches 1 GHz and the internal delay is very short to measure, so the internal delay of the PW-GW can be ignored.

10 shows a communication delay between the power link MN and the PW-GW.

As shown in Fig. 7, the power link PDO transmission method was used to transfer data between the power link MN and the PW-GW. The measured Powerlink PDO transmission delay here is the time difference at the power link MN that sends the request (PReq CN1) and receives the response (PRes CN1) from CN1 (ie, PW-GW) We measured the delay using Wireshark (a free open source packet analyzer) and the average power link PDO transmission delay was 1.897ms.

Figure 11 shows the communication delay between the wireless HART manager and the wireless HART device (mote).

In a wireless HART network, a wireless HART manager and a wireless HART device communicate in a fixed time slot as shown in FIG. The measured wireless HART delay here is the time difference in the wireless HART manager which sends a request (STX) and receives an acknowledgment (ACK) from the wireless HART device. The delay was measured using a Texas Instruments Packet Sniffer. The average wireless HART delay was 3.198ms.

Figures 10 and 11 show that the PW-GW according to the present invention is sufficient for industrial applications requiring real-time performance of tens of milliseconds. Only one hop delay between the wireless HART manager and the wireless HART device without the message queue was considered. Multi-hop network delay is considered in the smart mesh wireless HART application node.

The present invention provides a Linux-based open PW-GW solution. One of the major problems with this solution is that there is no protocol conversion method between the power link protocol and the wireless HART protocol. Accordingly, the present invention proposes an application layer protocol conversion method for establishing a gap between a power link and a wireless HART. PW-GW hardware and software have been developed and an experimental system has been built to demonstrate its functions and performance. System communication delays were measured to ensure that the PW-GW meets real-time requirements for time-sensitive industrial applications.

Future developments can place PW-GW and wireless HART FDs in smart factories with legacy Ethernet power link systems to increase process insight, reduce cable and installation costs, and improve the overall operational performance of the industrial facility.

10: Power link management node (MN) 20: Ethernet power link
30: Power link control node (CN) 31: Power link PLC
33: Industrial Equipment 40: Power Link Wireless HART Gateway
41: Protocol conversion section 43: Wireless HART management section
50: Wireless HART device

Claims (16)

A power link management node (MN) for controlling industrial equipment connected to the Ethernet power link,
A plurality of wireless HART devices (mote) existing on a wireless HART network,
And a Power Link Wireless HART Gateway (PW-GW) connecting to the Ethernet Power Link to perform protocol conversion between the Power Link Management Node and the plurality of Wireless HART Devices between the Power Link Protocol and the Wireless HART Protocol. Wireless HART system. The method according to claim 1,
Wherein the power link wireless HART gateway comprises: a wireless HART manager for communicating with the plurality of wireless HART devices by the wireless HART command of the power link management node and receiving information from each of the wireless HART devices;
A parser for receiving and parsing information of each wireless HART device from the wireless HART manager,
And a memory for storing a wireless HART command of the power link management node and an object dictionary (OD) for recording information of each parsed wireless HART device. 3. The method of claim 2,
Wherein the power link management node transmits the wireless HART command to the power link wireless HART gateway via a power link process data object (PDO) transmission. 3. The method of claim 2,
Wherein the power link management node periodically reads an object dictionary (OD) of the memory periodically through transmission of a power link process data object (PDO) to obtain information of each wireless HART device. HART system. A parser for receiving and parsing information of a plurality of wireless HART devices existing on a wireless HART network,
And a memory for writing the wireless HART command received from the power link management node and the information of each wireless HART device parsed by the parsing section in a power link object dictionary. 6. The method of claim 5,
Further comprising a wireless HART manager for receiving information from each of the wireless HART devices while communicating with the plurality of wireless HART devices by a wireless HART command of the power link management node. Transmitting a wireless HART command to a power link wireless HART gateway;
The wireless HART gateway recording the wireless HART command in an internal memory power link object dictionary (OD)
The wireless HART gateway configuring a wireless HART network by a wireless HART command recorded in the power link object dictionary and communicating with a plurality of wireless HART devices to collect information from the plurality of wireless HART devices,
Parsing the information of each wireless HART device collected by the wireless HART gateway and individually recording the information in the power link object dictionary;
And the power link management node acquiring information of each of the wireless HART devices from the power link object dictionary (OD). 8. The method of claim 7,
Wherein the power link management node transmits the wireless HART command to the wireless HART gateway via a Power Link Process Data Object (PDO) transmission. 8. The method of claim 7,
Wherein the power link management node periodically reads the object dictionary (OD) periodically through transmission of a power link process data object (PDO) to obtain information of each wireless HART device. . Receiving a wireless HART command from a power link management node and writing it in a power link object dictionary,
Configuring a wireless HART network by a wireless HART command recorded in the power link object dictionary and communicating with a plurality of wireless HART devices to collect information from the plurality of wireless HART devices,
Parsing the collected information of each wireless HART device and storing the parsed information in the power link object dictionary. 11. The method of claim 10,
And receiving the wireless HART command via a power link process data object (PDO) transmission from the power link management node. 11. The method of claim 10,
Wherein each of the parsed wireless HART information is stored as an index and subindex for each object in the power link object dictionary. Receiving a wireless HART command from a power link management node and writing it in a power link object dictionary,
Sending a wireless HART command recorded in the power link object dictionary to a wireless HART manager;
Receiving and parsing information of a plurality of wireless HART devices existing on a wireless HART network from the wireless HART manager;
And writing information of each parsed wireless HART device to a power link object dictionary. 13. The method of claim 12,
And receiving the wireless HART command via a power link process data object (PDO) transmission from the power link management node. 13. The method of claim 12,
Wherein each of the parsed wireless HART information is stored as an index and subindex for each object in the power link object dictionary. A computer-readable recording medium storing a program for executing the method according to any one of claims 10 to 15.

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