PLC analog module with hart transparent interface

Abstract

The present application relates to a PLC analog module supporting HART protocol, which can make a resource management server effectively manage a plurality of HART supporting devices by supporting modulation / demodulation of HART signal and interface of PLC system, thereby having an effect of saving time and cost required for maintenance and management.

Description

Technical Field

[0001] This invention relates to PLC (Programmable Logic Controller) modules, and more particularly to a PLC simulation module that supports the HART protocol. Background Technology

[0002] The HART (Highway Addressable Remote Transducer) protocol was developed by Rosemount in the mid-1980s. The HART protocol allows monitoring of the status of intelligent transmitters configured to remotely perform intelligent functions. Therefore, intelligent transmitters need built-in communication capabilities, employing industry standards such as HART, Foundation Fieldbus, and Profibus (Procedure Field Bus).

[0003] The HART protocol utilizes existing lines with common transmitters offering 4 to 20 mA current output to perform digital communication. It transmits data modulated using FSK (Frequency Shift Keying) over existing analog lines. HART communication is used to transmit status diagnostics, additional measurements, or calculated values ​​from smart transmitters. Such smart devices play a crucial role in equipment and asset management in today's industrial sectors.

[0004] PLCs are control devices widely used in industrial settings for automatic control and monitoring. A PLC operates based on user-input programs, sequentially processing the program logically and controlling connected external devices according to the results. For example, if an input signal enters a switch, it will be processed by the program's internal operating mechanism, and the result will ultimately be output to a coil.

[0005] Although over 30 million transmitters worldwide support the HART protocol, it is difficult to find PLC modules that support it. Therefore, in PLC systems, the HART protocol cannot be used unless a HART communication module compatible with the PLC device is used.

[0006] Figure 1 This is an example of the configuration of an existing PLC system using the HART protocol, as described above.

[0007] In addition to the existing basic module 10 and the control management device 20 that executes control management software, the PLC system also needs to include an intelligent transmitter interface 30 for receiving signals from the HART transmitter 40 and an analog module 12 for converting HART protocol signals, which are analog signals, into digital signals and providing them to the PLC system.

[0008] Therefore, in order to support the HART protocol in the PLC system, additional devices such as the intelligent transmitter interface 30 are required. Representative devices include HART handheld communicators and HART multiplexers.

[0009] However, since HART handheld communicators can only be used in the field where smart transmitters are installed, there are issues with the cost and time required to move them to the field. The disadvantage of HART multiplexers is that they occupy panel space in the PLC system and consume additional power.

[0010] To address the problems with existing smart transmitter interfaces, the inventors of this invention have conducted continuous research. After considerable effort, this invention was completed, developing a method for effectively managing multiple smart transmitters in a PLC system without using additional smart transmitter interfaces. Summary of the Invention

[0011] The problem the invention aims to solve

[0012] The purpose of this invention is to optimize remote PLC systems in real time and diagnose and resolve problems by adding the HART protocol to the control layer of a PLC system and utilizing intelligent transmitters that support HART communication even without additional devices for HART communication.

[0013] On the other hand, other objects not mentioned in this invention may be considered in addition to those that can be readily deduced from the following detailed description and their effects.

[0014] means for solving problems

[0015] The PLC analog module with a HART pass-through interface of the present invention is characterized by comprising: a HART interface for converting HART signals received from a plurality of HART-supporting devices into digital signals; a CPU interface for communication with a PLC CPU module; an AMS interface for communication with asset management software (AMS) of an asset management server; a memory shared with the PLC CPU module or the asset management server; and a control unit including one or more processors; wherein the HART interface supports HART pass-through.

[0016] The control unit can use the CPU interface to transmit HART instructions received from the asset management server to the PLC CPU module, and receive HART instructions from the PLC CPU module again and transmit them to a plurality of HART-supported devices using the HART interface.

[0017] The memory is shared by the control unit and the PLC CPU module, and message exchange between the PLC simulation module and the PLC CPU module is implemented using the memory.

[0018] Preferably, the memory structure includes message status, message order, message size, and HART message field to exchange messages between the PLC simulation module and the PLC CPU module.

[0019] The control unit will directly transmit the HART messages received from multiple HART-supported devices to the resource management server via the AMS interface using the HART Pass Through function of the HART interface.

[0020] Another embodiment of the present invention provides a HART communication method executed by a PLC simulation module, which includes a HART interface supporting HART pass-through function and PLC communication function. The method includes: receiving HART instructions from an asset management server; transmitting the HART instructions to a PLC CPU module; receiving the HART instructions with additional metadata from the PLC CPU module; and transmitting the HART instructions to a HART support device.

[0021] After the step of transmitting the HART instruction to the HART support device, the method may further include: receiving a HART response generated by the HART support device by appending metadata to the HART instruction; transmitting the HART response to the PLC CPU module; and receiving the HART response from the PLC CPU module and transmitting it to the asset management server.

[0022] Preferably, passing the HART instruction to the PLC CPU module means writing the HART instruction into the common memory of the PLC CPU module and the PLC simulation module so that the PLC CPU module can read it.

[0023] The effects of the invention

[0024] According to the present invention, no additional device for supporting the HART protocol is required in the PLC system, thus providing a simpler remote HART communication path. Therefore, it has the advantage of improving the productivity and availability of the entire system.

[0025] In addition, because the entire system can be integrated, it is easy to maintain and can save costs.

[0026] On the other hand, it should be clarified that even effects not explicitly mentioned herein, the effects and potential effects expected through the technical features of the present invention as described in the following specification are all considered to be described in the specification of the present invention. Attached Figure Description

[0027] Figure 1 This is a diagram illustrating the configuration of a PLC system that supports the HART protocol in existing technology.

[0028] Figure 2 This is a configuration diagram of a PLC system supporting the HART protocol according to any preferred embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram of a PLC system supporting the HART protocol according to another embodiment of the present invention.

[0030] Figure 4 This is a more detailed structural diagram of the HART module according to another embodiment of the present invention.

[0031] Figure 5 This is a schematic diagram of a PLC system supporting the HART protocol according to another embodiment of the present invention.

[0032] Figures 6 to 8 A flowchart illustrating the sending and receiving of HART commands according to a preferred embodiment of the present invention is shown.

[0033] Figure 9 This is an example of parameter setting for performing HART communication in any preferred embodiment of the present invention.

[0034] It should be clarified that the accompanying drawings are provided for reference only to understand the technical concept of the present invention, and do not limit the scope of protection of the present invention. Detailed Implementation

[0035] Hereinafter, with reference to the accompanying drawings, the various embodiments of the present invention and the effects obtained from the higher configurations will be described. Detailed descriptions of known functions relevant to the description of the present invention will be omitted where they are obvious to those skilled in the art and are judged to potentially obscure the essence of the invention.

[0036] The terms "first," "second," etc., can be used to describe various constituent elements, but these constituent elements should not be limited to the terms used above. The terms used above are only used to distinguish one constituent element from another. For example, without departing from the scope of the invention, "first constituent element" can be named "second constituent element," and similarly, "second constituent element" can be named "first constituent element." Furthermore, unless the context clearly specifies otherwise, singular expressions include plural expressions. Unless otherwise defined, the terms used in the embodiments of the invention can be interpreted as having meanings known to those skilled in the art.

[0037] Hereinafter, with reference to the accompanying drawings, the various embodiments of the present invention and the effects obtained from the present invention will be described.

[0038] Figure 1 The configuration of a conventional PLC system supporting the HART protocol is briefly shown.

[0039] The PLC system consists of a CPU module 10 that uses a CPU to control the entire system and an expansion module (addition module).

[0040] CPU module 10 is controlled by control management software called PADT (Programming and Debugging Tool) from control device 20. Control device 20 is composed of a desktop PC, laptop PC, etc., and executes user programs, and transmits the results to CPU module 10 to control the added module.

[0041] A plurality of HART transmitters 40, 42, and 44 transmit analog signals to a smart transmitter interface 30. The smart transmitter interface 30 includes: a terminal block 34 for connection between the smart transmitter interface 30 and the plurality of HART transmitters 40, 42, and 44; and a communication module 32 for converting HART signals into digital signals.

[0042] The HART analog signal input to terminal block 34 is transmitted to the analog module 12 of the PLC system or to the communication module 32 and converted into a digital signal. A HART multiplexer (MUX) can be used as the smart transmitter interface 30, and a HART modem can be used as the communication module 32. The HART protocol has a master / slave structure; when the master requests communication, the measuring instrument, acting as a slave, responds to form a communication. In the master / slave structure, up to two masters can be designated, and in the data link layer, the two masters can communicate with each other alternately with the slaves. Therefore, other master devices can be attached to the HART transmitter 40 connected to the PLC analog module 12. As an additional master device, a measuring instrument used for diagnosing the HART transmitter is typically used.

[0043] HART networks can be constructed in either Single Mode or Multi-Drop Mode. In Single Mode, analog signals ranging from 4 to 20 mA can be used, but in Multi-Drop Mode, the analog output value needs to be fixed at a minimum value.

[0044] The asset management server 50 is used to manage field devices such as HART transmitters. Depending on the field situation, the number of HART transmitters can increase to dozens or hundreds, thus requiring a device for managing these HART transmitters. Therefore, the asset management server 50 uses asset management software to manage multiple HART transmitters.

[0045] However, when using the smart transmitter interface 30 to connect multiple HART transmitters in this way, there is a problem that although wiring and operation costs increase, the communication throughput allocated to each transmitter actually decreases. Furthermore, as the number of HART transmitters increases, not only does the number of smart transmitter interfaces 30 need to increase, but the number of managed objects also increases, thus increasing management costs as well.

[0046] Therefore, the present invention addresses the problems of the prior art by adding a module to the PLC system itself to support the HART protocol, thereby building an integrated environment.

[0047] Figure 2 This is a schematic structural diagram of a PLC system including a HART module that supports the HART protocol, according to any preferred embodiment of the present invention.

[0048] The PLC system includes a CPU module 112, a communication module 114, and a HART module 116.

[0049] CPU module 112 is used to transmit instructions from control management device 120 to multiple PLC extension modules. In control management device 120, PADT is executed to execute the user's program, and CPU module 112 is used to transmit multiple control instructions.

[0050] Communication module 114 enables asset management server 130 to connect to a PLC system. For this purpose, the asset management software of asset management server 130 needs to be able to recognize multiple PLC devices, and a software driver called DTM (Device Type Manager) provided by the PLC manufacturer is installed in asset management server 130.

[0051] HART module 116 receives multiple HART analog signals from multiple HART transmitters 142, 144, 146 and converts them into digital signals for transmission to control management device 120 or asset management server 130. Conversely, HART messages intended for transmission in control management device 120 or asset management server 130 are converted into HART analog signals and transmitted to multiple HART transmitters 142, 144, 146. For this purpose, an analog module with HART modulation / demodulation capabilities is required.

[0052] HART module 116 includes memory that can be shared with CPU module 112 for transmitting HART data. Message passing between HART module 116 and CPU module 112 is implemented using this memory. Table 1 below shows an example of the memory structure used for message passing.

[0053] [Table 1]

[0054] meaning Message Status Message order Message size HART News byte size 2 2 2 64

[0055] The "Message Status" field contains code used to confirm whether the HART module 116 has read the HART message written by the CPU module 112. The "Message Order" field contains code used to confirm the pairing of the message requested by the CPU module 112 and the message responded to by the HART module 116. The "Message Size" field contains the size of the message transmitted by the asset management server 130 or responded to by multiple HART transmitters 142, 144, and 146. The "HART Message" field contains the actual HART message transmitted.

[0056] As described above, in this invention, by enabling the control management device 120 to support a pass-through mode that only transmits HART messages without parsing them, the control management server 130 can directly send or receive HART messages through PLC programming.

[0057] Figure 3 The configuration of a PLC system according to another embodiment of the present invention is shown.

[0058] The PLC system consists only of CPU module 212 and HART module 214, and is connected to control management device 220 and asset management server 230.

[0059] Since the HART module 214 performs the functions of the PLC communication module, a communication module for connecting to the asset management server 230 is not required.

[0060] Figure 4 A more detailed structure of the HART module 214 used here is shown.

[0061] HART module 214 includes HART terminal block 2141, HART interface 2142, CPU interface 2143, Asset Management Server (AMS) interface 2144, control unit 2145, and memory 2146.

[0062] HART terminal block 2141 connects HART-supported devices, such as HART transmitters, to HART module 214.

[0063] The HART interface 2142 performs modulation / demodulation functions to extract digital signals from HART analog signals or to convert digital signals into HART analog signals.

[0064] CPU interface 2143 is used for communication between HART module 214 and CPU module 212, and AMS interface 2144 is used to connect asset management server 230 to PLC system. DTM (Device Type Manager) needs to be installed in the asset management software of asset management server 230 to connect asset management server 230 to PLC system.

[0065] The memory 2146 is used to send and receive HART messages with the CPU module 212. HART messages are transmitted by writing or reading HART messages into the publicly accessible memory 2146, the structure of which is described above.

[0066] The control unit 2145 includes one or more processors. It receives HART messages from the asset management server 230 or the control management device 220 and transmits them to a plurality of HART-supported devices via the HART interface 2142, or it transmits HART messages received from a plurality of HART-supported devices to the asset management server 230 or the control management device 220.

[0067] Figure 5 This is a structural diagram of a PLC system according to another embodiment of the present invention.

[0068] When there are few HART-supported devices, the control and management device 320 directly manages multiple HART-supported devices without using a resource management server.

[0069] Figure 6 This is a flowchart of the HART message transmission process of the PLC system supporting the HART protocol according to the present invention.

[0070] The asset management server transmits HART instructions to the PLC communication module (S10), and the communication module then transmits the HART instructions to the CPU module (S20).

[0071] The CPU module passes the metadata to the HART module after including it in the HART instruction (S30).

[0072] The HART module modulates HART commands into analog signals and transmits them to the HART transmitter (S40).

[0073] The HART transmitter generates a HART response by appending metadata to the received HART command and then passes it to the HART module (S50).

[0074] The HART module demodulates the HART analog signal received from the HART transmitter into a digital signal and transmits it to the CPU module (S60).

[0075] The CPU module passes the HART response to the communication module without parsing or managing it (S70), and the communication module passes the HART response to the asset management server (S80).

[0076] Thus, by supporting the pass-through function in the CPU module to directly transmit multiple HART messages to the asset management server without parsing, it has the advantages of reducing the load on the control and management device and the CPU module, and enabling the asset management server to manage multiple HART-supported devices in an integrated manner.

[0077] Figure 7 This is a flowchart of HART message passing according to another embodiment of the present invention.

[0078] In addition to the modulation / demodulation function of HART analog signals, the HART module can also include the function of a communication module for communication between the asset management server and the CPU module. Therefore, communication between the asset management server and multiple HART-enabled devices can be simplified as follows: Figure 7 As shown.

[0079] The asset management server can use PLC instructions to directly transmit HART instructions to the HART module (S110) without going through the communication module or CPU module.

[0080] The HART module modulates HART commands into analog signals and transmits them to the HART transmitter (S120).

[0081] If the HART transmitter generates a HART response by appending metadata to the HART instruction and transmits it to the HART module (S130), the HART module demodulates the analog signal into a digital signal and transmits it to the asset management server (S140).

[0082] Figure 8 This is a flowchart of transmitting HART messages in user mode.

[0083] In such Figure 5 In the small system shown, multiple HART-supported devices can be directly managed using a control and management device included in the PLC system without using a pass-through mode.

[0084] The control device transmits HART instructions to the CPU module (S210), and the CPU module appends metadata to the HART instructions and transmits them to the HART module (S220).

[0085] The HART module modulates HART commands into analog form and sends them to the HART transmitter (S230).

[0086] The HART transmitter generates a HART response by appending metadata to the HART instruction, and then passes it to the HART module (S240).

[0087] The HART module converts the HART analog signal into a digital signal and transmits it to the CPU module (S250). The CPU module then transmits the HART response to the control device (S260).

[0088] As mentioned above, a user interface is needed to distinguish between pass-through mode and user program mode.

[0089] Figure 9 An example of this user-defined mode is shown.

[0090] The display allows you to set the HART module to Disable, User Program Mode, or Pass-through Mode.

[0091] Through the various embodiments of the present invention described above, users have the advantage of being able to freely expand HART-supported devices and more conveniently integrate and manage multiple HART-supported devices.

[0092] The scope of protection of this invention is not limited to the embodiments described and illustrated above. Furthermore, it is reiterated that obvious modifications or substitutions within the technical field to which this invention pertains should not limit the scope of protection of this invention.

Claims

1. A PLC analog module with a HART transparent transmission interface, characterized in that, include: PLC CPU module; as well as The HART module is connected to the PLC CPU module, multiple HART-supporting devices, and the AMS of the asset management server. The PLC CPU module includes metadata in the HART message received from the control and management device and then passes it to the HART module. The PLC CPU module transmits the HART messages without parsing them. The HART module includes: The HART interface converts HART signals received from a plurality of HART-enabled devices into digital signals; CPU interface, used for communication with the PLC CPU module; The AMS interface is used for communication with the AMS of the asset management server; The memory is shared with the PLC CPU module or asset management server; and The control unit includes one or more processors; The asset management server is equipped with a device type manager for communicating with the PLC device; The AMS interface will transmit HART messages received from a plurality of HART-supported devices to the asset management server using a pass-through function. The memory is shared by the control unit and the PLC CPU module, and message exchange between the HART module and the PLC CPU module is implemented using the memory; The memory stores and shares message status, message order, message size, and HART message fields.

2. A HART communication method executed by a PLC simulation module, wherein the PLC simulation module includes a HART interface supporting HART pass-through function and PLC communication function, characterized in that, The HART communication method includes: The steps to set up the device type manager in the asset management server for communicating with PLC devices; The steps to receive the first HART message from the asset management server; The step of transmitting the first HART message to the HART-supported device using the pass-through function; The step of transmitting the first HART protocol-enabled response received from the HART-enabled device to the asset management server using a pass-through function. The steps for receiving a second HART message from the control and management device; The step of passing the second HART message to the PLC CPU module; In the PLC CPU module, the step of transmitting the second HART message containing metadata to the HART module; In the HART module, the step of transmitting the second HART message containing the metadata to the HART support device; The step of storing a second HART protocol-supporting response received from the HART-supporting device in a shared memory without parsing it; The step of the PLC CPU module accessing the shared memory to obtain the second response; and The step of the PLC CPU module transmitting the second response to the control and management device; The memory stores and shares message status, message order, message size, and HART message fields.

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