Profibus-DP communication interface circuit and Profibus-DP communication system

Abstract

The invention discloses a Profibus-DP communication interface circuit and a Profibus-DP communication system, the Profibus-DP communication interface circuit comprises an isolation conversion circuit, a single-chip microcomputer signal processing circuit and a power supply circuit, the power supply circuit is used for supplying power to the whole Profibus-DP communication interface circuit, the isolation conversion circuit is connected with a DP connector, and the isolation conversion circuit is connected with the DP connector. A DP communication protocol processing circuit is arranged between the isolation conversion circuit and the single-chip microcomputer signal processing circuit, and the single-chip microcomputer signal processing circuit exchanges data with slave station speed regulation control equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of speed control electric drive systems, and particularly to a Profibus-DP communication interface circuit and a Profibus-DP communication system. Background Art

[0002] In the field of speed control electric drive systems, by adopting Profibus-DP communication technology, remote monitoring and precise control of frequency converters can be achieved, which simplifies operations while improving the reliability of the system, and flexible function modification can be carried out according to process requirements. As a widely used fieldbus technology, Profibus-DP has advantages such as high reliability, high real-time performance, and easy expansion. It can realize digital communication between devices, thus simplifying wiring, improving the reliability and flexibility of the system.

[0003] Currently, some frequency converters provide RS485 communication interfaces and use the internationally standard Modbus communication protocol for master-slave communication. If a frequency converter with Profibus-DP communication function is produced, adding Profibus-DP communication function to the main control board or operation panel of the frequency converter will greatly increase the cost of the frequency converter. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and provides a Profibus-DP communication interface circuit and a Profibus-DP communication system.

[0005] The technical solution of the present invention is realized as follows: The present invention discloses a Profibus-DP communication interface circuit, including an isolation conversion circuit, a single-chip microcomputer signal processing circuit, and a power supply circuit. The power supply circuit is used to supply power to the entire Profibus-DP communication interface circuit. The isolation conversion circuit is connected to a DP connector, and a DP communication protocol processing circuit is provided between the isolation conversion circuit and the single-chip microcomputer signal processing circuit.

[0006] Further, the isolation conversion circuit includes an isolator chip U8. One end of the first differential signal line A of the isolator chip U8 is connected to one end of a matching resistor R26. The other end of the matching resistor R26 is connected to one end of the second winding of a common-mode inductor L2. The other end of the second winding of the common-mode inductor L2 is connected to the third pin of a connector. One end of the second differential signal line B of the isolator chip U8 is connected to one end of a matching resistor R24. The other end of the matching resistor R24 is connected to one end of the first winding of the common-mode inductor L2. The other end of the first winding of the common-mode inductor L2 is connected to the eighth pin of the connector. The RXD pin of the isolator chip U8 is respectively connected to one end of a resistor R18, one end of a capacitor C79, and one end of a resistor R22. The other end of the resistor R18 is connected to a first voltage. The other end of the capacitor C79 is grounded. The other end of the resistor R22 is connected to the RXD pin of a DP communication protocol processing circuit. The TXD pin of the isolator chip U8 is respectively connected to one end of a resistor R19, one end of a capacitor C80, and one end of a resistor R28. The other end of the resistor R19 is connected to the first voltage. The other end of the capacitor C80 is grounded. The other end of the resistor R28 is connected to the TXD pin of the DP communication protocol processing circuit. The RTS pin of the isolator chip U8 is respectively connected to one end of a resistor R20, one end of a capacitor C81, and the RTS pin of the DP communication protocol processing circuit. The other end of the resistor R20 is connected to the first voltage. The other end of the capacitor C81 is grounded.

[0007] Further, the Profibus-DP communication interface circuit further includes an OR gate U4. The first input pin of the OR gate U4 is connected to one end of a resistor R16, the second input pin of the OR gate U4, and one end of a resistor R17. The other end of the resistor R16 is respectively connected to the other end of the resistor R17, the RTS pin of the DP communication protocol processing circuit, and the RESET pin of the DP communication protocol processing circuit. The output end of the OR gate U4 is connected to the RTS pin of the isolator chip U8. The RESET pin of the DP communication protocol processing circuit is connected to one end of a resistor R8. The other end of the resistor R8 is connected to the first voltage.

[0008] Further, the isolation conversion circuit further includes an ESD static protection diode D3 and an ESD static protection diode D4. One end of the ESD static protection diode D3 is connected to the first differential signal line A of the isolator chip U8 and one end of the matching resistor R26. The other end of the ESD static protection diode D3 is grounded. One end of the ESD static protection diode D4 is connected to the second differential signal line B of the isolator chip U8 and one end of the matching resistor R24. The other end of the ESD static protection diode D4 is grounded;

[0009] Or / and,

[0010] The isolation conversion circuit further includes a capacitor C76 and a capacitor C75. One end of the capacitor C76 is connected to the other end of the matching resistor R26 and one end of the second winding of the common-mode inductor L2, and the other end of the capacitor C76 is grounded. One end of the capacitor C75 is connected to the other end of the matching resistor R24 and one end of the first winding of the common-mode inductor L2, and the other end of the capacitor C75 is grounded;

[0011] Or / and,

[0012] The isolation conversion circuit further includes a resistor R21 and a resistor R29. One end of the resistor R21 is connected to the other end of the matching resistor R24 and one end of the first winding of the common-mode inductor L2, and the other end of the resistor R21 is grounded; One end of the resistor R29 is connected to the other end of the matching resistor R26 and one end of the second winding of the common-mode inductor L2, and the other end of the resistor R29 is grounded;

[0013] Or / and,

[0014] The isolation conversion circuit further includes a TVS diode D11 and a TVS diode D10. One end of the TVS diode D11 is connected to the other end of the first winding of the common-mode inductor L2 and the eighth pin of the connector, and the other end of the TVS diode D11 is grounded. One end of the TVS diode D10 is connected to the other end of the second winding of the common-mode inductor L2 and the third pin of the connector, and the other end of the TVS diode D10 is grounded.

[0015] Further, the DP communication protocol processing circuit is used to process the protocol data of Profibus-DP and transmit the processed data to the single-chip microcomputer signal processing circuit. The single-chip microcomputer signal processing circuit controls the Profibus-DP communication process by driving the DP communication protocol processing circuit.

[0016] Further, the DP communication protocol processing circuit adopts a VPC3+CLF3 protocol chip.

[0017] Further, the single-chip microcomputer signal processing circuit exchanges data with the slave speed control device;

[0018] The slave speed control device includes a main control circuit and a buffer circuit. The buffer circuit is connected between the main control circuit and the single-chip microcomputer signal processing circuit. The buffer circuit is used to buffer the SPI protocol data of the single-chip microcomputer signal processing circuit and then send it to the main control circuit.

[0019] Further, the main control circuit adopts a DSP chip.

[0020] The present invention also discloses a Profibus-DP communication system, which includes a slave station and a PLC master station. The slave station includes a DP communication interface board and a slave station speed control device. The DP communication interface board communicates with the slave station speed control device, and the DP communication interface board adopts the Profibus-DP communication interface circuit as described above.

[0021] Further, the DP communication interface board communicates with the slave station speed control device through an SPI bus.

[0022] Further, the DP communication interface board is connected to the PLC master station through a DP cable.

[0023] The present invention has at least the following beneficial effects: The Profibus-DP communication interface circuit of the present invention includes an RS485 isolation conversion circuit, a DP communication protocol processing circuit, and a single-chip microcomputer signal processing circuit. The RS485 isolation conversion circuit is used for the DP communication signal transmission between the slave station drive device and the PLC master station, and isolates the signal to improve the anti-interference ability of the system. The DP communication protocol processing circuit integrates all Profibus-DP protocols and is used to analyze the PROFIBUS-DP protocol. The single-chip microcomputer signal processing circuit is used to implement the configuration and management of the Profibus-DP slave station module and realize protocol data exchange. The Profibus-DP communication interface circuit of the present invention has stable communication quality and can perform serial communication for multiple units.

[0024] The present invention can use the DP communication interface board as a peripheral device of the frequency converter, convert the Modbus communication protocol data of the frequency converter into Profibus-DP protocol data through this communication expansion card, so as to realize network communication with other Profibus-DP fieldbus industrial devices, reduce costs, and at the same time do not affect the normal use of the frequency converter. The same terminal on the frequency converter can switch the board card according to different communication types, and the DP communication interface board is only one of the expansion board cards. Different expansion board cards adopt a compatible method, insert and remove the terminals, and the board cards are easy to install and replace. Moreover, the DP communication expansion circuit board of the frequency converter product has a simple circuit and a small board card area. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a Profibus-DP communication system architecture diagram.

[0026] Figure 2 It is a schematic diagram of the Profibus-DP communication interface circuit provided by an embodiment of the present invention;

[0027] Figure 3 It is a circuit diagram of the isolation conversion circuit provided by an embodiment of the present invention;

[0028] Figure 4 The circuit diagram of the DP communication protocol processing circuit provided by an embodiment of the present invention;

[0029] Figure 5 The circuit diagram of the single-chip microcomputer signal processing circuit provided by an embodiment of the present invention;

[0030] Figure 6 The circuit diagram of the buffer circuit provided by an embodiment of the present invention;

[0031] Figure 7 The circuit diagram of the power supply circuit provided by an embodiment of the present invention. Detailed implementation manners

[0032] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0033] Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meanings understood by those of ordinary skill in the art to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. In the description of the present invention, unless otherwise stated, the meanings of "a plurality of", "several" are two or more. Similarly, terms such as "one", "a" or "the" do not indicate a quantity limitation, but indicate the existence of at least one. Terms such as "including" or "comprising" mean that the elements or objects appearing before this term cover the elements or objects listed after this term and their equivalents, without excluding other elements or objects. Terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "lower", "left", "right", etc. are only used to represent relative positional relationships, and when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0034] In each of the accompanying drawings, the same elements are denoted by similar reference numerals. For the sake of clarity, not all parts in the drawings are drawn to scale. In addition, some well-known parts may not be shown in the figures.

[0035] In the following text, many specific details of the present invention are described, such as the structure, materials, dimensions, processing techniques and technologies of components, in order to better understand the present invention. However, as those skilled in the art can understand, the present invention can be implemented without these specific details.

[0036] See Figures 1 to 7, an embodiment of the present invention discloses a Profibus-DP communication interface circuit, including an isolation conversion circuit, a single-chip microcomputer signal processing circuit, and a power supply circuit. The power supply circuit is used to supply power to the entire Profibus-DP communication interface circuit. The isolation conversion circuit is connected to a DP connector. A DP communication protocol processing circuit is provided between the isolation conversion circuit and the single-chip microcomputer signal processing circuit. The single-chip microcomputer signal processing circuit exchanges data with a slave speed control device.

[0037] See Figure 7 , the power supply circuit is used to convert a 24V voltage into the voltages required by the Profibus-DP communication interface circuit, such as 5V1 and 3.3V, etc.

[0038] Further, the isolation conversion circuit is an RS485 isolation conversion circuit. The RS485 isolation conversion circuit is used for the DP communication signal transmission between the slave drive device and the PLC master station, and isolates the signal to improve the anti-interference ability of the system.

[0039] Further, the isolation conversion circuit includes an isolator chip U8. One end of the first differential signal line A of the isolator chip U8 is connected to one end of a matching resistor R26. The other end of the matching resistor R26 is connected to one end of the second winding of a common mode inductor L2. The other end of the second winding of the common mode inductor L2 is connected to the third pin of the connector. One end of the second differential signal line B of the isolator chip U8 is connected to one end of a matching resistor R24. The other end of the matching resistor R24 is connected to one end of the first winding of the common mode inductor L2. The other end of the first winding of the common mode inductor L2 is connected to the eighth pin of the connector. The RXD pin of the isolator chip U8 is respectively connected to one end of a resistor R18, one end of a capacitor C79, and one end of a resistor R22. The other end of the resistor R18 is connected to a first voltage. The other end of the capacitor C79 is grounded. The other end of the resistor R22 is connected to the RXD pin of the DP communication protocol processing circuit. The TXD pin of the isolator chip U8 is respectively connected to one end of a resistor R19, one end of a capacitor C80, and one end of a resistor R28. The other end of the resistor R19 is connected to a first voltage. The other end of the capacitor C80 is grounded. The other end of the resistor R28 is connected to the TXD pin of the DP communication protocol processing circuit. The RTS pin of the isolator chip U8 is respectively connected to one end of a resistor R20, one end of a capacitor C81, and the RTS pin of the DP communication protocol processing circuit. The other end of the resistor R20 is connected to a first voltage. The other end of the capacitor C81 is grounded.

[0040] In some embodiments, the isolator chip U8 uses the ADM2486BRWZ chip, which has an isolation function and can improve the anti-interference ability of the circuit. The bus-side signals of the isolator chip U8 are DP-A and DP-B, and these signals are connected to the DP connector through a matching resistor and a common-mode inductor. The DP connector is connected to an external PLC master station through a DP cable. The matching resistor is adjusted according to the actual situation on site, and 10 ohm is generally recommended; the common-mode inductor plays a role in suppressing common-mode interference. The chip logic-side signals are the request-to-send signal, the receive signal, and the send signal. Among them, the request-to-send signal is active high. When this signal is at a high level, the chip driver is enabled; otherwise, the driver is invalid. The receive signal is to receive DP data from the PLC master station and transfer it to the transmission equipment, and the send signal is to send DP data from the transmission equipment to the PLC master station.

[0041] Further, the Profibus-DP communication interface circuit further includes an OR gate U4. The first input pin of the OR gate U4 is connected to one end of a resistor R16, the second input pin of the OR gate U4 and one end of a resistor R17. The other end of the resistor R16 is respectively connected to the other end of the resistor R17, the RTS pin of the DP communication protocol processing circuit, and the RESET pin of the DP communication protocol processing circuit. The output end of the OR gate U4 is connected to the RTS pin of the isolator chip U8. The RESET pin of the DP communication protocol processing circuit is connected to one end of a resistor R8, and the other end of the resistor R8 is connected to a first voltage. The OR gate U4 is used as a logical OR and has a buffering and filtering effect on the input signals.

[0042] In some embodiments, the first voltage is 3.3V.

[0043] Further, the isolation conversion circuit further includes an ESD protection diode D3 and an ESD protection diode D4. One end of the ESD protection diode D3 is connected to the first differential signal line A of the isolator chip U8 and one end of a matching resistor R26, and the other end of the ESD protection diode D3 is grounded. One end of the ESD protection diode D4 is connected to the second differential signal line B of the isolator chip U8 and one end of a matching resistor R24, and the other end of the ESD protection diode D4 is grounded.

[0044] Further, the isolation conversion circuit further includes a capacitor C76 and a capacitor C75. One end of the capacitor C76 is connected to the other end of the matching resistor R26 and one end of the second winding of the common-mode inductor L2, and the other end of the capacitor C76 is grounded. One end of the capacitor C75 is connected to the other end of the matching resistor R24 and one end of the first winding of the common-mode inductor L2, and the other end of the capacitor C75 is grounded.

[0045] Further, the isolation conversion circuit further includes a resistor R21 and a resistor R29. One end of the resistor R21 is connected to the other end of the matching resistor R24 and one end of the first winding of the common mode inductor L2, and the other end of the resistor R21 is grounded; one end of the resistor R29 is connected to the other end of the matching resistor R26 and one end of the second winding of the common mode inductor L2, and the other end of the resistor R29 is grounded.

[0046] Further, the isolation conversion circuit further includes a TVS tube D11 and a TVS tube D10. One end of the TVS tube D11 is connected to the other end of the first winding of the common mode inductor L2 and the eighth pin of the connector, and the other end of the TVS tube D11 is grounded; one end of the TVS tube D10 is connected to the other end of the second winding of the common mode inductor L2 and the third pin of the connector, and the other end of the TVS tube D10 is grounded. The TVS tube D11 and the TVS tube D10 have the functions of preventing surges and static electricity.

[0047] Further, the DP communication protocol processing circuit analyzes the PROFIBUS-DP protocol by using a dedicated chip, and the single-chip microcomputer signal processing circuit is used to implement the configuration and management of the Profibus-DP slave module and to implement protocol data exchange.

[0048] In some embodiments, the DP communication protocol processing circuit uses a VPC3 + CLF3 protocol chip. This chip integrates all the Profibus-DP protocols, enabling it to easily communicate with the Profibus-DP master station, automatically identify and support data transfer rates up to 12 Mbit / s, thus meeting the requirements of high-speed communication. Through the VPC3 + CLF3 protocol chip, information processing, address recognition, data security sorting, and protocol processing of Profibus-DP are completed to ensure the accurate transmission of data and the stability of communication, and the processed data is transmitted to the single-chip microcomputer signal processing circuit. The single-chip microcomputer signal processing circuit controls the Profibus-DP communication process by driving the VPC3 + CLF3, including communication interface inspection, sending diagnostic data and data exchange in normal and faulty situations, analyzing the response frame (or communication timeout) of the input / output module to determine the status of the module and the channel status of the module, filling the data of the diagnostic domain of Profubus-DP according to the module status information, and controlling the gateway status (normal communication, reporting error or warning information) based on this.

[0049] The diagnostic domain of Profibus-DP has a specific format and definition. It usually contains fields for representing information such as device status, fault type, fault location, etc. According to the module status and channel status information parsed from the response frame of the input / output module, it is mapped according to the requirements of the Profibus-DP diagnostic domain. For example, if a module has a certain specific fault type, find the corresponding fault code field in the diagnostic domain, and write the fault code into this field and feedback it to the master unit for communication status monitoring through the upper computer.

[0050] Control the gateway status based on the diagnostic domain data: According to specific application requirements, formulate the gateway status control logic based on the Profibus-DP diagnostic domain data. For example, if the diagnostic domain shows that the module has a serious fault, the gateway may be set to enter the error handling mode, stop data forwarding or send alarm information to other related devices. By reading the diagnostic parameters of Profibus-DP, change the working status of the gateway according to the predefined control logic.

[0051] See Figures 1 to 7 , the embodiment of the present invention also discloses a Profibus-DP communication system, including a slave station and a PLC master station. The slave station includes a DP communication interface board and a slave station speed control device. The DP communication interface board communicates with the slave station speed control device, and the DP communication interface board adopts the Profibus-DP communication interface circuit as described above.

[0052] Furthermore, the slave station speed control device includes a main control circuit.

[0053] Furthermore, the slave station speed control device further includes a buffer circuit. The buffer circuit is connected between the main control circuit and the single-chip microcomputer signal processing circuit. The buffer circuit is used to buffer the SPI protocol data of the single-chip microcomputer signal processing circuit and then send it to the main control circuit.

[0054] In some embodiments, the buffer circuit adopts a buffer chip with the model number 74LVTH244MTC.

[0055] Furthermore, the main control circuit adopts a DSP chip.

[0056] Furthermore, the DP communication interface board communicates with the slave station speed control device through the SPI bus.

[0057] Furthermore, the DP communication interface board is connected to the PLC master station through a DP cable. The PLC master station sends or receives DP communication data through the DP communication interface circuit. The DP communication interface circuit parses the DP data and transfers it to the slave station device using the SPI protocol.

[0058] The communication expansion card for Profibus-DP protocol data has the advantages of simple structure, low cost, easy installation, etc., and can be widely applied to various electric drive control systems.

[0059] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A Profibus-DP communication interface circuit, characterized in that: It includes an isolation conversion circuit, a single-chip microcomputer signal processing circuit and a power supply circuit. The power supply circuit is used to supply power to the entire Profibus-DP communication interface circuit. The isolation conversion circuit is connected to a DP connector, and a DP communication protocol processing circuit is provided between the isolation conversion circuit and the single-chip microcomputer signal processing circuit.

2. The Profibus-DP communication interface circuit according to claim 1, characterized in that: The isolation conversion circuit includes an isolator chip U8. One end of the first differential signal line A of the isolator chip U8 is connected to one end of a matching resistor R26. The other end of the matching resistor R26 is connected to one end of the second winding of a common-mode inductor L2. The other end of the second winding of the common-mode inductor L2 is connected to the third pin of the connector. One end of the second differential signal line B of the isolator chip U8 is connected to one end of a matching resistor R24. The other end of the matching resistor R24 is connected to one end of the first winding of the common-mode inductor L2. The other end of the first winding of the common-mode inductor L2 is connected to the eighth pin of the connector. The RXD pin of the isolator chip U8 is respectively connected to one end of a resistor R18, one end of a capacitor C79 and one end of a resistor R22. The other end of the resistor R18 is connected to a first voltage. The other end of the capacitor C79 is grounded. The other end of the resistor R22 is connected to the RXD pin of the DP communication protocol processing circuit. The TXD pin of the isolator chip U8 is respectively connected to one end of a resistor R19, one end of a capacitor C80 and one end of a resistor R28. The other end of the resistor R19 is connected to a first voltage. The other end of the capacitor C80 is grounded. The other end of the resistor R28 is connected to the TXD pin of the DP communication protocol processing circuit. The RTS pin of the isolator chip U8 is respectively connected to one end of a resistor R20, one end of a capacitor C81 and the RTS pin of the DP communication protocol processing circuit. The other end of the resistor R20 is connected to a first voltage. The other end of the capacitor C81 is grounded.

3. The Profibus-DP communication interface circuit according to claim 2, wherein: It also includes an OR gate U4. The first input pin of the OR gate U4 is connected to one end of a resistor R16, the second input pin of the OR gate U4 and one end of a resistor R17. The other end of the resistor R16 is respectively connected to the other end of the resistor R17, the RTS pin of the DP communication protocol processing circuit and the RESET pin of the DP communication protocol processing circuit. The output end of the OR gate U4 is connected to the RTS pin of the isolator chip U8. The RESET pin of the DP communication protocol processing circuit is connected to one end of a resistor R8. The other end of the resistor R8 is connected to a first voltage.

4. The Profibus-DP communication interface circuit according to claim 2 or 3, characterized in that: The isolation conversion circuit also includes an ESD static protection diode D3 and an ESD static protection diode D4. One end of the ESD static protection diode D3 is connected to the first differential signal line A of the isolator chip U8 and one end of the matching resistor R26. The other end of the ESD static protection diode D3 is grounded. One end of the ESD static protection diode D4 is connected to the second differential signal line B of the isolator chip U8 and one end of the matching resistor R24. The other end of the ESD static protection diode D4 is grounded; Or / and, The isolation conversion circuit further includes a capacitor C76 and a capacitor C75. One end of the capacitor C76 is connected to the other end of the matching resistor R26 and one end of the second winding of the common mode inductor L2. The other end of the capacitor C76 is grounded. One end of the capacitor C75 is connected to the other end of the matching resistor R24 and one end of the first winding of the common mode inductor L2. The other end of the capacitor C75 is grounded; Or / and, The isolation conversion circuit further includes a resistor R21 and a resistor R29. One end of the resistor R21 is connected to the other end of the matching resistor R24 and one end of the first winding of the common mode inductor L2. The other end of the resistor R21 is grounded; One end of the resistor R29 is connected to the other end of the matching resistor R26 and one end of the second winding of the common mode inductor L2. The other end of the resistor R29 is grounded; Or / and, The isolation conversion circuit further includes a TVS tube D11 and a TVS tube D10. One end of the TVS tube D11 is connected to the other end of the first winding of the common mode inductor L2 and the eighth pin of the connector. The other end of the TVS tube D11 is grounded. One end of the TVS tube D10 is connected to the other end of the second winding of the common mode inductor L2 and the third pin of the connector. The other end of the TVS tube D10 is grounded.

5. The Profibus-DP communication interface circuit according to claim 1, characterized in that: The DP communication protocol processing circuit is used to process the protocol data of Profibus-DP and transmit the processed data to the single-chip microcomputer signal processing circuit. The single-chip microcomputer signal processing circuit controls the Profibus-DP communication process by driving the DP communication protocol processing circuit.

6. The Profibus-DP communication interface circuit according to claim 1, characterized in that: The single-chip microcomputer signal processing circuit exchanges data with the slave speed control device; The slave speed control device includes a main control circuit and a buffer circuit. The buffer circuit is connected between the main control circuit and the single-chip microcomputer signal processing circuit. The buffer circuit is used to buffer the SPI protocol data of the single-chip microcomputer signal processing circuit and then send it to the main control circuit.

7. The Profibus-DP communication interface circuit according to claim 6, characterized in that: The main control circuit uses a DSP chip.

8. A Profibus-DP communication system, characterized in that: It includes a slave station and a PLC master station. The slave station includes a DP communication interface board and a slave speed control device. The DP communication interface board communicates with the slave speed control device. The DP communication interface board adopts the Profibus-DP communication interface circuit as described in any one of claims 1 to 7.

9. The Profibus-DP communication system according to claim 1, characterized in that: The DP communication interface board communicates with the slave speed control device through the SPI bus.

10. The Profibus-DP communication system according to claim 1, characterized in that: The DP communication interface board is connected to the PLC master station through a DP cable.

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