Method and system for smoothly displaying instantaneous waveform of human-computer interface

Abstract

The invention relates to the technical field of industrial automation control, in particular to a human-computer interface instantaneous waveform smooth display method and system. A frequency converter controller collects real-time data and stores the real-time data in a cache; the operation control unit reads the number of channels needing to be read in the real-time data command; the frequency converter controller extracts real-time data of the number of channels in the command at the same acquisition moment from the cache; a waveform display unit of the human-computer interface draws a continuous waveform; and the operation control unit judges whether the current waveform display is full of a screen or not, and if the current waveform display is not full of the screen, the data reading process continues to be executed. The method has the advantages that a high-precision acquisition timestamp is added to each data point, so that a human-computer interface can accurately draw on a time axis according to the real acquisition time of the data instead of depending on a fixed screen refresh cycle, the problem of waveform distortion caused by the fact that the data updating rate is lower than the display refresh rate is fundamentally solved, and the accuracy of the data updating rate is improved. The actual operation state of the frequency converter is truly reflected.

Description

Technical Field

[0001] This invention relates to the field of industrial automation control technology, and in particular to a method and system for smooth display of instantaneous waveforms in a human-machine interface. Background Technology

[0002] Displaying the inverter's operating waveforms (such as voltage and current waveforms) in real time on a human-machine interface (such as an industrial touchscreen) is an important means of monitoring the inverter's operating status and performing system debugging. Currently, the industry commonly uses industrial touchscreens from brands such as Kunlun Tongtai and Weintek as human-machine interfaces, and designs the interface using the configuration software provided by the manufacturers.

[0003] Configuration software typically provides dedicated real-time curve controls for waveform display. A typical implementation in existing technology involves the human-machine interface continuously reading the latest data points from the frequency converter controller via the Modbus protocol at a fixed refresh cycle and plotting them on the real-time curve control.

[0004] However, this traditional method has two significant drawbacks:

[0005] 1. The waveform display is distorted, showing a "virtual plateau":

[0006] The internal refresh rate of real-time curve controls in human-machine interfaces is typically high and fixed, while the data reading rate of Modbus communication is limited by factors such as protocol overhead and controller load, often lower than the display refresh rate. This results in waveform data not being updated within multiple display refresh cycles, forcing the real-time curve control to draw the same data value multiple times on the time axis, thus displaying a false, flat waveform on the screen, i.e., a "virtual plateau." For example, a smooth 50Hz sine wave will appear as a distorted waveform with obvious steps on the screen, severely affecting the user's judgment of the device's true operating status.

[0007] 2. Multi-channel data is out of sync, resulting in phase distortion:

[0008] When multiple waveforms with phase relationships need to be displayed simultaneously (such as three-phase voltage), existing technologies require reading data from each channel sequentially. Due to the time difference in the reading operation, the obtained U, V, and W three-phase voltage values ​​are not strictly sampled at the same moment. Using this asynchronous data to draw waveforms will distort the displayed phase relationship and fail to accurately reflect the working condition of the power grid or motor; this is known as a data integrity problem.

[0009] To address the aforementioned issues, some existing technologies have attempted to use interpolation algorithms to smooth waveforms. However, this method has significant shortcomings: interpolation itself does not add real sampling information, and the generated data points are also "false," failing to accurately reflect the instantaneous state of the frequency converter and potentially introducing misleading information. Furthermore, interpolation algorithms increase the system's computational overhead and implementation complexity. As for the data integrity issues caused by multi-channel data asynchrony, existing technologies lack effective and low-cost solutions.

[0010] Therefore, there is an urgent need for a method that can effectively eliminate "virtual platforms," ​​ensure synchronous display of multi-channel data, and achieve simple and low-cost waveform smoothing. Summary of the Invention

[0011] The purpose of this invention is to provide a method and system for smoothing instantaneous waveform display in a human-machine interface, which overcomes the two major problems of "virtual platform" and "data asynchrony" in waveform display in industrial sites in a simple and low-cost way, and significantly improves the display quality and data reliability of the monitoring interface.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] A method for smoothing instantaneous waveform display in a human-computer interface includes:

[0014] When the real-time curve display is started on the human-machine interface, the operation control unit sends a clear cache command to the frequency converter controller;

[0015] The inverter controller responds to the clear buffer command, starts collecting real-time data and storing it in the buffer, and pauses data collection after the buffer condition is met;

[0016] The operation control unit sends a command to the frequency converter controller to read real-time data. The command contains the number of channels to be read.

[0017] The inverter controller extracts the real-time data of the number of channels from the command at the same acquisition time from the cache according to the real-time data read command, and uploads the timestamp data together to the human-machine interface.

[0018] The waveform display unit of the human-machine interface draws continuous waveforms based on the received real-time data and its acquisition timestamp data;

[0019] The control unit determines whether the current waveform display is full. If it is not full, the data reading process continues. If it is full, the clear cache command is re-initiated and the above process is repeated.

[0020] The caching condition is that the data cache is full.

[0021] When the frequency converter controller collects real-time data, it collects signals from multiple channels each time it is interrupted, and records the collection time of each data point.

[0022] The system collects real-time data including the inverter's three-phase voltage, three-phase current, output frequency, speed, and DC bus voltage. Users can arbitrarily select and display channels via commands to display combined waveforms of various real-time data on the interface.

[0023] The packaged and uploaded data packets are transmitted via the Modbus protocol, and the packets contain address identifiers used to distinguish real-time curve data.

[0024] The human-machine interface uses real-time curve controls provided by the configuration software and continuously draws data based on the timestamp information of the data points.

[0025] A human-machine interface instantaneous waveform smoothing display system includes a frequency converter controller. The frequency converter controller includes a signal acquisition unit, a data storage unit, a data packaging unit, and a data transmission unit. The signal acquisition unit is used to acquire multi-channel real-time signals, the data storage unit is used to store the acquired real-time data, the data packaging unit is used to package multiple channel data at the same time with the acquisition time information, and the data transmission unit is used to upload the packaged data to the human-machine interface.

[0026] It also includes a human-machine interface, which includes a running control unit, a data storage and retrieval unit, a waveform display unit, and an optional data cache unit. The running control unit is used to control the data acquisition and reading process, the data storage and retrieval unit is used to communicate with the frequency converter controller, the waveform display unit is used to draw real-time curves, and the optional data cache unit is used to temporarily store the data read from the frequency converter.

[0027] The human-machine interface is an industrial touch screen.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. By attaching a high-precision acquisition timestamp to each data point, the human-machine interface can accurately draw on the timeline based on the actual acquisition time of the data, rather than relying on a fixed screen refresh cycle. This fundamentally solves the waveform distortion problem caused by the data update rate being lower than the display refresh rate, ensuring that the displayed waveform is continuous and smooth, and truly reflects the actual operating status of the frequency converter.

[0030] 2. By specifying the number of channels in a single read command, the inverter controller returns data from multiple channels at the same acquisition time, ensuring that waveform data with strict phase relationships, such as three-phase voltage and current, are synchronized. This avoids phase distortion caused by reading data from different channels at different times, providing a reliable basis for accurate system analysis and fault diagnosis.

[0031] 3. No complex interpolation algorithms or additional hardware support are required. The optimization of data acquisition, packaging and display logic can be achieved by making full use of the timing interrupt capability of existing frequency converter controllers (such as DSP) and the existing functions of human-machine interface configuration software (such as curve controls that support timestamps) through software-level improvements. It has extremely high cost performance and engineering practical value.

[0032] 4. It adopts an "on-demand acquisition" working mode, which only starts the data acquisition and transmission process when the user needs to view the waveform. This not only reduces the normal load on the inverter controller and communication bus, but also avoids the frequent transmission of invalid data, so that system resources can be more effectively used for core control tasks.

[0033] 5. This invention does not depend on specific hardware chips or configuration software brands. As long as the human-machine interface and the frequency converter controller can establish communication and support waveform display with timestamp concept, this method can be applied. It has good portability and broad applicability. Attached Figure Description

[0034] Figure 1 It is the structure of the instantaneous waveform smoothing display system for human-machine interface. Figure 1 .

[0035] Figure 2 This is a flowchart of a method for smoothing instantaneous waveforms in a human-machine interface.

[0036] Figure 3 It is the structure of the instantaneous waveform smoothing display system for human-machine interface. Figure 2 .

[0037] Figure 4 The real-time curve is displayed using a human-machine interface that does not employ the present invention.

[0038] Figure 5 It is a real-time curve displayed using the human-machine interface of this invention. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings, but it should be noted that the implementation of the present invention is not limited to the following embodiments.

[0040] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0041] Example 1

[0042] This invention places the operation control unit within the human-machine interface (HMI) and the data storage unit within the frequency converter controller. When the real-time curve on the HMI is not being viewed, the frequency converter does not collect new data, and the operation control unit on the HMI does not operate or read waveform data from the frequency converter. When the real-time curve is being viewed on the HMI, the operation control unit notifies the frequency converter to start collecting new real-time data via the data access unit, and then the operation control unit reads the real-time data from the frequency converter. The operation control unit ensures the integrity of the data read each time. When the frequency converter uploads the data it collects, it also uploads the acquisition time information for each data point. The waveform display unit on the HMI plots the waveform data sent by the frequency converter. Since each data point contains acquisition time information, the waveform plotted by the HMI based on the sampling time is continuous, without any virtual plateaus.

[0043] See Figure 1 A human-machine interface instantaneous waveform smoothing display system includes a frequency converter controller and a human-machine interface. The frequency converter controller uses a TMS320F28335 chip, but other models can also be used. The frequency converter controller includes a signal acquisition unit, a data storage unit, a data packaging unit, and a data transmission unit. The signal acquisition unit uses an ADS8555 chip, but other models can also be used, for acquiring multi-channel real-time signals. The data storage unit is used to store the acquired real-time data. The data packaging unit is used to package multiple channel data at the same time with the acquisition time information into corresponding transmission messages for data transmission. The data transmission unit is used to upload the packaged data to the human-machine interface for real-time curve plotting.

[0044] The human-machine interface (HMI) is an industrial touchscreen. The HMI includes a control unit, a data storage unit, a waveform display unit, and an optional data buffer unit. The control unit is responsible for starting the inverter controller's signal acquisition unit, specifying the number of real-time data channels to be packaged by the inverter controller's data packaging unit, reading data from the data buffer unit, and sending the data to the waveform display unit. The data buffer unit is responsible for buffering the real-time data read from the inverter controller. The waveform display unit is responsible for using the real-time data to draw real-time curves on the HMI and provides waveform scaling and screen clearing control functions. The data storage unit is used to communicate with the inverter controller.

[0045] See Figure 2 A method for smoothing instantaneous waveform display in a human-computer interface includes the following steps:

[0046] Step 1: Bring up the real-time curve display interface on the human-machine interface:

[0047] The operation control unit clears the curve display interface once;

[0048] The data access unit sends a clear buffer command to the frequency converter controller.

[0049] The frequency converter controller starts data acquisition and buffering; when the buffer is full, acquisition stops.

[0050] Step 2: The operation control unit issues a real-time data read command through the data access unit to read real-time data from the frequency converter controller; after receiving the read command, the frequency converter controller retrieves the required amount of real-time data from the data buffer unit, packages it together with the data collected at the time of acquisition, and uploads it to the human-machine interface through the data transmission unit.

[0051] Data integrity is guaranteed by the operation control unit. The read command issued by the operation control unit contains the number of channels of real-time data to be read. The real-time data of each channel is the data at the same acquisition time, ensuring that the phase relationship between waveforms will not be distorted when different waveforms are plotted, thereby ensuring data integrity.

[0052] For example, to read the input three-phase voltage data, the control command issued by the operation control unit contains information from three channels. Taking reading three-phase voltage as an example, it is necessary to read the voltage data of phase A, phase B, and phase C, which are these three channels. Since the frequency converter can collect data from 18 channels, the frequency converter needs to select these three channels of data from the 18 channels according to the channels in the command and upload them to the operation controller. The input three-phase voltage data collected at the same time is packaged together with the data at the time of collection and uploaded together.

[0053] Step 3: The waveform display unit 18 uses the newly obtained real-time data to plot a real-time curve on the human-machine interface.

[0054] Step 4: The control unit determines whether the currently set horizontal display width of the curve has displayed the complete curve. If it is not fully displayed, continue to step 2. If it is fully displayed, proceed to step 1 to collect new real-time data and draw it again.

[0055] Step 5: The inverter controller waits for commands from the HMI. When it receives the clear cache command from the HMI in Step 1, it executes Step 6; otherwise, it continues to wait.

[0056] Step 6: Clear the cache.

[0057] Step 7: Collect new data and save it to the data cache unit.

[0058] Step 8: If the cache is full, stop data collection and proceed to Step 5, waiting for commands from the human-machine interface. If the cache is not full, execute Step 7 to continue collecting real-time data.

[0059] Step 9: When the frequency converter controller receives the data reading command from the human-machine interface, it parses the reading command, retrieves the corresponding real-time data and the data collected at the time of acquisition from the data cache unit, packages them together, and uploads them to the human-machine interface through the data transmission unit.

[0060] Example 2

[0061] In this embodiment, the method and system for smoothing instantaneous waveform display of a human-machine interface are the same as in Embodiment 1, with the addition of a working process.

[0062] See Figure 3 The frequency converter controller is based on TI's TMS320F28335 chip, and the human-machine interface (HMI) uses Kunlun Tongtai's TPC1271Hi. The frequency converter controller and HMI communicate via Modbus RTU, with the HMI as the master station and the frequency converter controller as the slave station. Waveform plotting uses the real-time curve control provided by Kunlun Tongtai's configuration software, employing a relative clock curve mode. The operation control unit is implemented in the HMI using scripts, utilizing Kunlun Tongtai's Modbus device read / write interface to implement data access, sending commands to the frequency converter controller, including clearing the buffer and reading specific real-time data and channel numbers. The data buffer uses Kunlun Tongtai's real-time database. The frequency converter controller's signal acquisition unit uses three TI ADS8555 chips, capable of acquiring 18 analog signals. The data storage unit 12 utilizes the internal memory of the TMS320F28335 chip, implemented in an array-based queue format. Data packet 13 and data transmission unit are implemented in the Modbus communication protocol. They execute requests distinct from other Modbus data exchanges by parsing and reading addresses from the command, instead executing requests from data storage unit 12.

[0063] See Figure 4 and Figure 5 The figures show the three-phase input voltage curves of the frequency converter before and after using this invention, respectively. The input voltage is 10kV, which is converted into an analog signal of ±6V by a voltage sensor, and then converted into a digital quantity by the analog-to-digital converter chip ADS8555 and transmitted to the TMS320F28335 chip. These data are converted into actual voltage data, normalized, and then stored in the data storage unit. When the frequency converter controller receives a data transmission request, it first parses the channel information in the request, such as the three-phase input voltage in this example, and then extracts the three-phase voltage data from the data buffer according to this information and uploads it.

[0064] This invention addresses the waveform distortion caused by data update rates lower than display refresh rates by attaching a high-precision acquisition timestamp to each data point. This allows the human-machine interface to accurately plot data on the timeline based on the actual acquisition time, rather than relying on a fixed screen refresh rate. This ensures continuous and smooth waveforms, accurately reflecting the actual operating status of the inverter. By specifying the number of channels in a single read command, the inverter controller returns data from multiple channels at the same acquisition time, ensuring that waveforms with strict phase relationships, such as three-phase voltage and current, are synchronized. This avoids phase distortion caused by time-sharing reading of different channels, providing a reliable basis for accurate system analysis and fault diagnosis. Furthermore, it eliminates the need for complex interpolation algorithms or additional hardware support, simplifying data acquisition, packaging, and... The optimization of the display logic fully utilizes the timing interrupt capabilities of existing frequency converter controllers (such as DSPs) and the existing functions of human-machine interface configuration software (such as curve controls supporting timestamps). This can be achieved through software-level improvements, resulting in extremely high cost-effectiveness and practical engineering value. It adopts an "on-demand acquisition" working mode, initiating data acquisition and transmission only when the user needs to view the waveform. This not only reduces the normal load on the frequency converter controller and communication bus but also avoids frequent transmission of invalid data, allowing system resources to be more effectively used for core control tasks. This invention does not rely on specific hardware chips or configuration software brands. As long as communication can be established between the human-machine interface and the frequency converter controller, and waveform display with timestamps is supported, this method can be applied, demonstrating good portability and broad applicability.

Claims

1. A method for smoothing instantaneous waveform display in a human-machine interface, characterized in that, include: When the real-time curve display is started on the human-machine interface, the operation control unit sends a clear cache command to the frequency converter controller; The inverter controller responds to the clear buffer command, starts collecting real-time data and storing it in the buffer, and pauses data collection after the buffer condition is met; The operation control unit sends a command to the frequency converter controller to read real-time data. The command contains the number of channels to be read. The inverter controller extracts the real-time data of the number of channels from the command at the same acquisition time from the cache according to the real-time data read command, and uploads the timestamp data together to the human-machine interface. The waveform display unit of the human-machine interface draws continuous waveforms based on the received real-time data and its acquisition timestamp data; The control unit determines whether the current waveform display is full. If it is not full, the data reading process continues. If it is full, the clear cache command is re-initiated and the above process is repeated.

2. The method for smoothing instantaneous waveform display in a human-machine interface according to claim 1, characterized in that, The aforementioned caching condition is that the data cache is full.

3. The method for smoothing instantaneous waveform display in a human-machine interface according to claim 1, characterized in that, When acquiring real-time data, the inverter controller acquires signals from multiple channels each time it is interrupted, and records the acquisition time of each data point.

4. The method for smoothing instantaneous waveform display in a human-machine interface according to claim 3, characterized in that, The real-time data collected includes the inverter's three-phase voltage, three-phase current, output frequency, speed, and DC bus voltage. The channel to be read and displayed can be arbitrarily selected via commands, and the combined waveforms of various real-time data can be displayed on the interface.

5. The method for smoothing instantaneous waveform display in a human-machine interface according to claim 1, characterized in that, The packaged and uploaded data packets are transmitted via the Modbus protocol, and the packets contain address identifiers used to distinguish real-time curve data.

6. The method for smoothing instantaneous waveform display in a human-machine interface according to claim 1, characterized in that, The human-machine interface uses real-time curve controls provided by the configuration software and continuously draws based on the data collection timestamp information corresponding to the data points.

7. A human-machine interface instantaneous waveform smoothing display system for implementing the method of any one of claims 1-6, characterized in that, The system includes a frequency converter controller, which comprises a signal acquisition unit, a data storage unit, a data packaging unit, and a data transmission unit. The signal acquisition unit is used to acquire real-time signals from multiple channels, the data storage unit is used to store the acquired real-time data, the data packaging unit is used to package data from multiple channels at the same time with the acquisition time information, and the data transmission unit is used to upload the packaged data to the human-machine interface.

8. A human-machine interface instantaneous waveform smoothing display system according to claim 7, characterized in that, It also includes a human-machine interface, which includes a running control unit, a data storage and retrieval unit, a waveform display unit, and an optional data cache unit. The running control unit is used to control the data acquisition and reading process, the data storage and retrieval unit is used to communicate with the frequency converter controller, the waveform display unit is used to draw real-time curves, and the optional data cache unit is used to temporarily store the data read from the frequency converter.

9. A human-machine interface instantaneous waveform smoothing display system according to claim 8, characterized in that, The human-machine interface is an industrial touch screen.

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