Application aware Modbus gateway

Abstract

The invention relates to an application aware Modbus gateway. A Modbus gateway is disclosed that includes a processor, an application memory, and a data acquisition module for receiving field data from an industrial process running in a plant that includes processing equipment with associated field devices. The data acquisition module is coupled to provide the field data to a data agent, the data agent having at least one memory that stores the field data in accordance with a data register associated with the field device. The data broker is coupled to the application memory, the application memory containing at least one data mapping organized according to an application context requested by a subscribed client device for an application executing at the client device. The data broker is coupled to associate the data register to a packet of field data according to the data mapping, wherein the processor causes the packet of field data to be sent to a client device subscribing to the data mapping.

Description

Technical Field

[0001] The present disclosure generally relates to the field of industrial networks. More specifically, the present disclosure relates to an application-aware gateway device operating under the Modbus protocol. Background Art

[0002] Process control systems, such as those used in chemical, petroleum or other processes, typically include at least one central process controller that is communicatively coupled to at least one host or operator workstation and one or more field devices via analog and / or digital buses or other communication lines or channels. Field devices, such as valves, valve positioners, switches, transmitters (e.g., temperature, pressure and flow rate sensors), etc., perform functions within the process, such as opening or closing valves and measuring process parameters.

[0003] The process controller receives signals indicative of process measurements made by field devices and / or other information about the field devices via input / output (I / O) devices, uses this information to implement a control routine, and then generates control signals that are sent to the field devices via the input / output devices over a bus or other communication channel to control the operation of the process. Information from the field devices and controllers is typically made available to one or more applications executed by an operator workstation to enable an operator to perform any desired function related to the process, such as viewing the current state of the process, modifying the operation of the process, configuring the process, documenting the process, etc.

[0004] In the past, standard communication protocols were developed to enable controllers and field devices from different manufacturers to exchange data using a standard format. The Modbus protocol can define the message structure that controllers will recognize and use, regardless of the type of network they communicate over. The Modbus protocol creates a common format for the layout and content of message fields. Modbus defines processes for controllers to request access to other devices, for controllers and devices to respond to requests, and for error detection and reporting. During communication on a Modbus network, the protocol determines how each controller or device will know its device address, identify messages addressed to it, determine the type of action to be taken, and extract any data or other information contained in the message. If a reply is required, the controller or device will construct a reply message and send it using the Modbus protocol. The Modbus protocol is known in the art and is described in detail in many articles, manuals, and specifications that have been published, issued, and can be obtained from manufacturers of devices using the Modbus protocol. Therefore, the details of the Modbus communication protocol will not be described in detail unless they relate to the embodiments disclosed in the present invention.

[0005] Modbus uses a master-slave query-response cycle to exchange information between a controller and a field device. Each device can be assigned an address ranging from, for example, 1 to 255. A device (i.e., a "master") can initiate a transaction, such as a query, set point change, diagnosis, etc., by transmitting a message addressed to another device (i.e., a "slave"). Under the Modbus protocol, the message transmitted by the master is formatted to include the device address of the slave, the function code defining the requested action, any data to be sent to the slave, and error checking information. The slave detects and receives messages from the master based on the address in the message, and processes the transaction or function indicated by the function code in the message. After processing the transaction or executing the requested function, the slave transmits a response message constructed using the Modbus protocol and containing information confirming the action taken, any data to be returned to the master, and error checking information.

[0006] The response message transmitted by the slave device will typically include a register map to which configuration, input, and output data can be written and read from. The Modbus data model includes four basic mapping tables organized into a flat table structure consisting of discrete inputs, coil outputs, input registers, and holding registers. Data is organized based on data type and access type (i.e., holding, discrete, etc.). The discrete input mapping table allows random access to digital / Boolean inputs. The coil output mapping table is used for read / write access to digital / Boolean output data. The input register mapping table is used for read-only access to analog / 16-bit integer, while the holding register mapping table is used for read / write access to analog / 16-bit integer output data.

[0007] The Modbus flat table model described above is generally sufficient to provide a master-slave query-response cycle for exchanging information between a single controller and the assigned field devices. However, in some Modbus configurations, a Modbus data concentrator is used to act as a Modbus master for multiple Modbus slave devices. The Modbus concentrator is connected to several slave devices at the same time and provides access to data from all slave devices. However, as the flat data table becomes larger and larger due to the large number of slave devices, it becomes difficult to organize four basic mapping tables to associate any meaning or context with the data received from the slave devices.

[0008] Different applications may need to access different sets of data based on specific use cases from one or more field devices. For example, in order to control a slide, it may be necessary to access data from all elements of the slide, such as control data from a programmable logic controller (PLC) or input / output (I / O) modules. Certain applications need to access data at different priorities. For example, a control application will be interested in the key inputs and outputs of the system. However, a diagnostic / display application will need access to more data items, but at a slower rate for display / monitoring purposes.

[0009] The current Modbus data model does not provide a method to group or manage data at a level that a single application may need and monitor storage to manage field devices. Therefore, the present disclosure defines an application-aware gateway device that uses the Modbus protocol. Summary of the invention

[0010] This Summary is provided to introduce a brief selection of disclosed concepts in a simplified form, which are further described below in the Detailed Description including the provided figures. This Summary is not intended to limit the scope of the claimed subject matter.

[0011] A first disclosed embodiment includes a method for exchanging process data between processing equipment of an industrial process and at least one application executed at a client device. The method includes sending process data from the processing equipment of the industrial process to a gateway device. Sending a request for process data associated with an application context to the gateway device, creating a data map for the application context in at least one memory of the gateway device, and assigning a unit ID to the data map. The method associates the process data sent from the processing equipment to the gateway device with the data map to create a packet of process data for the application context, wherein the client device subscribes to the gateway device using the unit ID to receive the packet of process data.

[0012] A second disclosed embodiment includes a gateway device comprising a processor, an application memory, and a data acquisition module for receiving field data from an industrial process running in a plant, the plant comprising processing equipment with associated field devices. The data acquisition module is coupled to provide the field data to a data agent, the data agent having at least one memory, the at least one memory storing the field data according to a data register associated with the field device. The data agent is coupled to the application memory, the application memory comprising at least one data map, the at least one data map being organized according to an application context requested by a subscribed client device for an application executed at the client device. The data agent is coupled to associate the data register to a group of field data according to the data map, wherein the processor causes the group of field data to be sent to a client device subscribed to the data map.

[0013] The third disclosed embodiment includes a computer program product including a non-transitory data storage medium including program instructions executable by a processor to enable the processor to perform a method for exchanging process data between processing equipment of an industrial process and at least one application executed at a client device, the method comprising sending field data from the processing equipment to a gateway device from a field device associated with the industrial process. An application context representing an application use case executed at the client device is defined, and a data map for the application context is created in at least one memory of the gateway device, and a unit ID is assigned to the data map. Field data sent to the gateway device is selected to be associated with the data map, thereby creating a grouping of field data for the application context, wherein the client device subscribes to the gateway device using the unit ID to receive the grouping of field data.

[0014] Other technical features will be apparent to those skilled in the art from the following drawings, descriptions and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] For a more complete understanding of the present disclosure, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0016] Figure 1 is a flow chart illustrating steps in a method for exchanging data between a field device and a client using an application-aware Modbus gateway according to an example embodiment;

[0017] Figure 2 is a schematic diagram illustrating the communication organization of a field device and a client with a Modbus gateway according to an example embodiment;

[0018] Figure 3 is a diagram of data grouping of a Modbus mapping register table of a Modbus gateway according to an example embodiment;

[0019] Figure 4 is an illustration of a system configured to create application-aware packets of field data in a Modbus gateway according to an example embodiment;

[0020] Figure 5 is a flow chart illustrating a method for creating application-aware grouping of data using a system of Modbus gateways according to an example embodiment. DETAILED DESCRIPTION

[0021] These figures discussed below and the various embodiments for describing the principles of the present invention in this patent document are carried out by way of example only and should not be construed as limiting the scope of the present invention in any way. Those skilled in the art will appreciate that the principles of the present invention can be implemented in any type of suitably arranged device or system.

[0022] However, those skilled in the art will readily recognize that the subject matter disclosed herein can be practiced without one or more specific details or other methods. In other cases, known structures or operations are not shown in detail to avoid blurring certain aspects. The present disclosure is not limited by the order of the actions or events shown, because certain actions can occur in different orders and / or simultaneously with other actions or events. In addition, not all actions or events shown are necessary to implement the method according to the embodiments disclosed herein.

[0023] Additionally, the terms "coupled to" or "coupled with..." (etc.) as used herein without further qualification are intended to describe either an indirect or direct electrical connection. Thus, if a first device is "coupled" to a second device, the connection may be through a direct electrical connection, where only parasitics are present in the path, or through an indirect electrical connection via intermediary items including other devices and connections. For indirect coupling, the intermediary items generally do not modify the information of the signal, but may adjust its current level, voltage level, and / or power level.

[0024] As previously indicated, there are thousands of traditional industrial communication devices (e.g., Modbus field devices) in industrial plants, such as actuators, industrial power measurement instruments, process measurement transmitters, and other process measurement devices, and there is a need to facilitate communications between such devices and the control room and other systems and equipment.

[0025] It should be noted that the term "Modbus" as used in this article refers to a serial communications protocol for programmable logic controllers that was released by Modicon (now Schneider Electric) in 1979. Simple and robust, it has since become the de facto standard communications protocol and is now a common means of connecting industrial electronic equipment. The main reasons for using Modbus in industrial environments are that it was developed with industrial applications in mind, is easy to deploy and maintain, and can move raw bits or words without placing many restrictions on vendors. Modbus enables communication between many devices connected to the same network, such as a system that measures temperature and humidity and transmits the results to a computer. Modbus is often used to connect monitoring computers to RTUs in SCADA (Supervisory Control and Data Acquisition) systems.

[0026] It should be noted that although the example embodiments disclosed herein discuss various Modbus devices and systems, it should be understood that the disclosed embodiments are not limited to the use of the Modbus communication protocol, and other serial communication protocols may be considered. However, for exemplary purposes, Modbus is discussed herein as an example of a serial communication protocol present in many traditional devices in industrial applications.

[0027] The disclosed embodiments may help customers and other users allow any device (eg, a Modbus-enabled device) to group data from field devices at an industrial plant for use by applications executing at a client device, such as in a control room of the industrial plant.

[0028] Figure 1 is a flow chart showing steps in a method 10 for exchanging data between a field device and a client using an application-aware Modbus gateway according to an example embodiment. Step 15 includes sending a data packet from a factory (see Figure 2 Field data of an industrial process running in an industrial plant 115) in the embodiment of the present invention, the plant includes processing equipment with associated field devices 114a, 114b, 114c-114n. Figure 2 As shown in the schematic diagram of , the field devices 114a-114n may be composed of sensors and actuators (collectively referred to as field devices 114) operating using a serial Modbus communication protocol. The field data is transmitted uplink to the Modbus gateway 112 using a communication network 118, which acts as a concentrator for processing the field data from the field devices 114 so as to transmit the field data to clients 116a, 116b, and 116c (collectively referred to as clients 116) along a second communication network 119.

[0029] Figure 2The Modbus gateway 112 shown in is connected to field devices 114 and Modbus clients 116. Field devices 114 and clients 116 can be coupled to Modbus gateway 112 using serial communication protocol or Modbus TCP / IP communication protocol, and the Modbus TCP / IP communication protocol transmits Modbus protocol through Ethernet IP network. Field devices 114 may also include a Modbus TCP serial converter that converts serial data streams into Modbus TCP / IP protocol. Modbus gateway 112 is arranged to periodically poll field devices 114 to obtain data based on preconfigured data registers defined by Modbus clients 116. Modbus gateway 112 utilizes acquisition modules (such as, for example, scanners) to scan and poll field devices 114. The scanner ensures that field data is obtained regularly. The incidental task of the scanner is to cause an event when field devices 114 do not respond for some reason. However, field data can be streamed to Modbus gateway 112 in other ways. In another embodiment, the field device 114 may be a "smart" field device that is programmed to periodically (at regular or predetermined intervals) transmit field data to the gateway 112 rather than scanning measured field data as scanned data.

[0030] In step 20 of method 10, field data from field device 114 is coupled to Modbus gateway 112 using communication network 118. Communication network 118 can be made up of Ethernet IP bus or serial bus using Modbus remote terminal unit (RTU), and this serial bus uses serial communication protocol. Field data from field device 114 is cached in Modbus gateway 112 and is mapped to Modbus register mapping table. Field data in mapping register table is grouped into data table based on the specific context required by the application executed at client 116. Each client 116 can subscribe to Modbus gateway 112 with access to the grouped field data from being included in the data mapping for application use using using the unit ID of the data table.

[0031] Figure 3A diagram of data grouping of a Modbus mapped register table 305 included in a memory 310 of a Modbus gateway 112 is illustrated. The mapped register table 305 includes a plurality of data maps 301a, 301n based on a client application context. Field data from field devices 114a and 114b are collected from field device registers and stored in data maps 301a-301n according to the application context. For example, the application context of mapping 301a may include field data related to use by a control or diagnostic application of a client 116. The client 116 will subscribe to the Modbus gateway 112 to receive data from the data map 301a for use by the control or diagnostic application. The Modbus mapped register table 305 may also include at least a second data map 301n organized for another application context containing field data from field devices 114b-114n. The data map 301n is organized to provide field data for an application context of another client 116. For example, field data from data map 301n can be used by an application executing on client 116 using a display device in a control room of an industrial plant. Data map 301n is created to convey process data information, such as pressure, temperature, and device status, for display on the display device. Data map 301n is configured, depending on the context, to collect field data from field devices 114c-114n that is important in monitoring the process plant or the process controlled by the plant.

[0032] Based on the user-defined context of the client 116 application coupled to the Modbus gateway 112, the registers of the field devices 114a-114n can be set by the user to be associated with one or more data maps in the data maps 301a-301n. Each individual data map 301a-301n includes a unit ID that provides an identification to a unique data map. For example, the client 116 requesting data from the data map 301a will use a Modbus address containing a unit ID of 1. Another client 116 requesting data from the data map 301n will use a Modbus address containing a unit ID of 25.

[0033] like Figure 1 As shown in step 25 of , the field data contained in each data map 301a - 301n will be updated with any new or updated field data from its associated field device 114a - 114e.

[0034] Figure 4 is an illustration of a system 300 associated with an industrial plant 105 configured to create application-aware groupings of field data in a Modbus gateway 112 according to an example embodiment. Figure 4The embodiment of the system 300 illustrated in the block diagram is for illustration only. Other embodiments may be used without departing from the scope of the present disclosure.

[0035] The Modbus gateway 112 includes a data acquisition module 335 that functions as an input / output (I / O) module. The data acquisition module 335 may include an intelligent communication interface unit (CIU) that may provide an intelligent I / O interface that understands field devices or process equipment (e.g., instruments, tanks) installed at the industrial plant 105. Such a CIU may be responsible for acquiring field data from the field devices 114a-114n, performing data calculations, and presenting the data from the field devices to other modules of the Modbus gateway 112, such as the data agent 340, the processor 360, the visualization module 370, and the application memory 310.

[0036] Field devices 114a-114n in the industrial plant 105 provide measured field data. The field devices 114a-114n may also include actuators coupled to process equipment, such as storage tanks and valves configured to control industrial processes in a refining or distillation system, for example. The field devices 114a-114n are coupled to the data acquisition module 335 via a bus 118. The bus 118 may be a serial bus used in serial communication, such as MODBUS RTU, which utilizes a compact binary representation of data for protocol communication.

[0037] The process data from the plant 105 collected by the data acquisition module 335 is stored in a cache memory 335a of the data acquisition module 335. The data agent 340 periodically scans the cache memory 335a (e.g., random access memory) to collect new field data. This means that two asynchronous communication routines work with the same cache memory 335a. The data acquisition module 335 polls the field data from the field devices 114a-114n and stores the data in the cache memory 335a, while the data agent 340 polls the same cache memory 335 for updates. The field data from the acquisition module 335 cache memory 335a is coupled to the data agent memory 340a (e.g., random access memory), which stores the field data according to the data registers of the connected field devices.

[0038] The processor 360 may include a microprocessor, a digital signal processor (DSP), or a microcontroller unit (MCU). The processor 360 is communicatively coupled to the internal communication network 338 for receiving field data from a data agent 340 executing an operating program for managing the system 300. The processor 360 may also be communicatively coupled to an application memory 310 that stores a mapping register table 305 and associated data maps 301a-301n generated for client applications. The visualization module 370 is used by the system 300 as an interface to a graphical user interface (GUI) 385a executed at an operator station that serves as an engineering station 385 of the system 300. The visualization module 370 may include a visualization protocol for operating with the GUI 385a for displaying parameters that can be obtained from field devices based on data fields such as, for example, temperature, pressure, flow, commissioning and configuration, diagnostics, alarms, etc. The visualization protocol may also be accessed to operate within a browser on a PC serving as an engineering station. The visualization module 370 may also be arranged to provide a visualization protocol for display to a GUI operating on a mobile device or a mobile application running on a smart phone or tablet. The visualization module 370 may also support the GUI 385a to perform a variety of functions, such as extracting information, handling rounding and formatting of decimal places, and displaying the correct dimension units. Depending on the requirements, the value needs to be converted to another dimension and displayed with another number of decimal places. Colors with special meanings may be provided, and states generally need to be determined and displayed.

[0039] The processor 360 with input from the user via the engineering station 385 defines a data mapping to the field data contained in the data register, which is generated for a specific client application context data packet. The processor 360 builds a data map and assigns a unique user ID to the data map to identify it. The defined data maps 301a-301n are stored in the application memory 310 in the mapping register table 305. Each data map 301a-301n stored in the application memory 305 is subscribed by the client 116a-116c through a specific unit ID, and is arranged to be pushed from the application memory 310 to the communication network 119 for use by the client 116a-116c and its associated application. The communication network 119 can be a serial bus such as MODBUS RTU or MODBUS TCP / IP using the TCP / IP protocol, the latter coupling an Ethernet-enabled device through an Ethernet network using MODBUS message transmission.

[0040] Figure 5 is a flow chart illustrating a method 500 for creating application-aware packets of data using the system 300 of the Modbus gateway 112 according to an example embodiment.

[0041] In step 505, a user (such as, for example, a plant operator using an engineering station 385) enters a list of Modbus device addresses of field devices 114a-114n that will be used to define the application context of the client device. Figure 4 Client 116a in.

[0042] In step 510 , the engineering station 385 receives a request from a user and presents a list and selection menu to the user via the GUI 385 to define an application context.

[0043] In step 515, the user uses the list and selection menus presented by the GUI 385a to define an application context representing an application use case of the client application. For example, the user will define an application context representing a use case for control, diagnostics, display, processing area, etc.

[0044] In step 520, processor 360 receives the use case of the client application transmitted downlink from engineering station 385 via communication network 119. Processor 360 creates data map 301 in map data register 305 of application memory 310 for the use case selected by the user and assigns a unit ID to the data map.

[0045] Then, in step 525, the data registers contained in the data proxy memory 340a for the field device address identified in step 505 are selected by the user using the GUI 385a at the engineering station 385. The identified field device address is transmitted to the processor 360 to associate the field device registers with the data map. The data proxy memory 340a contains field data from the data registers of the field devices connected to the Modbus gateway 112.

[0046] Then, in step 530, the data registers contained in the memory 340a of the data agent 340 are associated with the data map 301 and the unit ID, thereby generating a group of field data for the application context contained in the data registers. Figure 3 As explained in , the selected field data may be from a data register of a single field device 114a - 114n , or from a data register of another field device 114a - 114n .

[0047] Then, in step 535, the user specifies a particular access priority to the data map based on the importance of the client application to the plant 150. For example, an application monitoring a safety system will have a higher access priority to field data than, for example, a diagnostic application context.

[0048] In step 540 , the user may request construction of additional context-related groupings by repeating steps 510 - 535 to create another data map 301 for another client application.

[0049] As mentioned above Figure 1 As discussed in , the client devices 116a - 116c may subscribe to the data map contained in the Modbus gateway 112 using a unique ID that couples field data from selected data registers to an application executing at the client device.

[0050] It may be advantageous to set forth the definitions of certain words and phrases used throughout this patent document. The term "communication" and its derivatives cover both direct communication and indirect communication. The terms "include" and "comprising" and their derivatives mean including but not limited to this. The term "or" is inclusive, meaning and / or. The phrase "associated with..." and its derivatives may mean including, included within, interconnected with, included within, connected to, or connected with, coupled to, or coupled with, can communicate with, collaborate with, interlace, juxtapose, approach, be coupled to, or be combined with, have, have the property of, have a relationship with, or have a relationship with. When used with a list of items, the phrase "at least one of..." means that different combinations of one or more items in the listed items may be used, and only one item in the list may be needed. For example, "at least one of A, B, and C" includes any combination of A, B, C, A and B, A and C, B and C, and A and B and C.

[0051] The description in this application should not be construed as implying that any particular element, step, or function is an essential or critical element that must be included within the scope of the claims. The scope of subject matter protected by a patent is limited only by the claims as allowed. In addition, none of the claims is intended to invoke 35 U.S.C. §112(f) with respect to any of the appended claims or claim elements, unless the exact words "means for..." or "step for..." followed by a participle phrase identifying the function are expressly used in a particular claim. The use of terms such as (but not limited to) "mechanism", "module", "device", "unit", "component", "element", "member", "device", "machine", "system" or "controller" within the claims is understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and is not intended to invoke 35 U.S.C. §112(f).

[0052] Although the present disclosure has described certain embodiments and generally associated methods, changes and permutations of these embodiments and methods will be apparent to those skilled in the art. Therefore, the above description of the exemplary embodiments does not limit or restrict the present disclosure. Other changes, substitutions and variations are also possible without departing from the spirit and scope of the present disclosure as defined in the following claims.

Claims

1. A method for exchanging process data between processing equipment of an industrial process and at least one application executed at a client device, comprising: sending process data from said processing equipment of said industrial process to a gateway device; sending a request for process data associated with the application context to the gateway device; creating a data map for the application context in at least one memory of the gateway device and assigning a unit ID to the data map; associating the process data sent from the processing equipment to the gateway device with the data map to create a grouping of process data for the application context, The client device subscribes to the gateway device using the unit ID to receive packets of the process data.

2. The method according to claim 1, wherein the step of sending process data from the processing equipment includes sending field data from a field device associated with the processing equipment of the industrial process to a data acquisition module at the gateway device, wherein the data acquisition module stores the field data in a data acquisition memory according to an address of the field device.

3. The method of claim 2, wherein the gateway device is communicatively coupled to an operator station executing a graphical user interface (GUI), the method comprising sending a visualization protocol from the gateway device to the GUI for displaying field data parameters from the field device.

4. A method according to claim 3, wherein the method includes a list of addresses of the field devices being input by a user using the GUI, the addresses to be used to define an application context for an application executed at the client device, and wherein the method includes using the GUI to define an application context representing an application use case of the application executed at the client device. 5 . The method according to claim 4 , wherein the user sends the application context and use case to the gateway device to create the data map.

6. The method of claim 5, wherein the method includes using the GUI to select by the user the field device to be associated with the data map, wherein the address of the field device is sent to the gateway device.

7. A gateway device, comprising: processor; Application memory; a data collection module for receiving field data from an industrial process operating in a plant including processing equipment having associated field devices; The data acquisition module is coupled to provide the field data to a data agent, the data agent having at least one memory, the at least one memory storing the field data according to a data register associated with the field device; wherein the data proxy is coupled to the application memory, the application memory containing at least one data map, the at least one data map being organized according to an application context requested by a subscribing client device for an application executing at the client device; The data agent is coupled to associate the data registers to groups of field data according to the data map; and Wherein the processor causes packets of the live data to be sent to the client devices subscribed to the data map.

8. The gateway device of claim 12, wherein the gateway device is communicatively coupled to an operator station executing a graphical user interface (GUI), and the gateway device includes a visualization module that sends a visualization protocol to the GUI for displaying field data parameters from the field device.

9. The gateway device of claim 13, wherein a user uses the GUI to input a list of addresses of the field devices to be used to define an application context for an application executing at the client device.

10. The gateway device of claim 9, wherein the user sends the application context and use case to the gateway device, where the processor creates the data map and stores the data map in the application memory along with a unit ID, wherein the user uses the GUI to select the field device for the data map, and wherein the address of the field device is sent to the gateway device, where the processor associates the data proxy field data register with the data map.

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