CN210721072U - Sensor data acquisition system based on LabVIEW and serial port communication - Google Patents

Abstract

The utility model belongs to the technical field of the measurement test, concretely relates to sensor data acquisition system based on LabVIEW and serial ports communication solves long time, the inefficiency that current displacement sensor calibration data acquisition method exists, easily makes mistakes or with high costs, development cycle length scheduling problem. Under the condition of not changing the existing manual calibration device, data transmission and collection with LabVIEW data collection software in a computer are realized through an RS232 serial port in the digital multimeter, linear precision calculation and uncertainty analysis are calculated, various defects of manually input data are avoided, and meanwhile, new equipment does not need to be purchased, and the cost is saved.

Description

Sensor data acquisition system based on LabVIEW and serial port communication

Technical Field

The utility model belongs to the technical field of the measurement test, a use digital multimeter RS232 interface and computer communication, utilize LabVIEW data acquisition system to carry out displacement sensor output signal collection system is related to.

Background

The displacement sensor is also called as a linear sensor and is widely applied to the fields of transportation, petroleum and coal, steel, ships, aerospace and the like.

Currently, there are two general methods for data acquisition related to displacement sensor calibration: the manual calibration device is used for analyzing and calculating an output electric signal by adopting a manual input computer; and the other one uses an automatic calibration device to realize automatic input of the output signals into a computer for analysis and calculation by using a DAQ automatic acquisition card and a GPIB bus. The disadvantages of the first method are: the calibration time is long, the efficiency is low, errors easily occur in hand input data, and the accuracy of a calibration result is influenced; although the second method overcomes the defects, corresponding automatic equipment and software need to be purchased, the cost is high, the investment is large, the design program code of the data acquisition software is complex, the development period is long, and certain programming knowledge requirements are provided for software development personnel.

SUMMERY OF THE UTILITY MODEL

In order to solve the long time that current displacement sensor calibration data acquisition method exists, inefficiency, easily make mistakes or with high costs, development cycle length scheduling problem, under the condition that does not change current manual calibrating device, the utility model provides a sensor data acquisition system based on LabVIEW and serial ports communication realizes carrying out data transmission collection with LabVIEW data acquisition software in the computer through the RS232 serial ports in the digital multimeter to calculate linear accuracy and calculate and the uncertainty analysis, avoided the various not enough of manual input data, simultaneously, also need not to purchase new equipment, practiced thrift the cost, solved the problem that exists among the prior art.

The technical solution of the utility model is to provide a sensor data acquisition system based on LabVIEW and serial ports communication, its special character lies in: the device comprises a displacement sensor calibration device, a direct-current voltage stabilizing source, a digital multimeter, a USB-to-RS 232 serial port line and a computer; the sensor to be calibrated is positioned on the displacement sensor calibration device, the direct-current voltage stabilizing source is connected with the power supply end of the sensor to be calibrated, and the digital multimeter is connected with the signal end of the sensor to be calibrated; two ends of the USB-to-RS 232 serial port line are respectively connected with the digital multimeter and the computer; LabVIEW data acquisition software is installed in the computer, and the digital multimeter is communicated with the LabVIEW data acquisition software and used for acquiring and storing the electric signals output by the sensor to be calibrated.

Further, the sensor to be calibrated is a linear displacement sensor or an angular displacement sensor.

Furthermore, in order to adjust the mutual position of the sensor to be calibrated and the calibration device, the system also comprises a lifting table and a pressing plate, wherein the pressing plate is used for fixing the sensor to be calibrated on the lifting table.

Further, the digital multimeter has a model number of Keithley 2000.

The utility model has the advantages that:

1. the utility model discloses on the basis of current manual calibrating device, make digital multimeter and LabVIEW data acquisition software communication in the computer, utilize LabVIEW data acquisition software to carry out data acquisition, collection precision, efficient, and need not to purchase new equipment, with low costs;

2. the LabVIEW data acquisition software adopted by the utility model has the advantages of good man-machine interface, high stability and simple operation, can greatly improve the calibration work efficiency and save the labor cost; meanwhile, the software is convenient to modify and debug due to the fact that graphical language programming is used.

Drawings

FIG. 1 is a schematic diagram of a sensor data acquisition system based on LabVIEW and serial port communication;

fig. 2 is a flow chart of the sensor data acquisition method based on LabVIEW and serial communication.

The reference numbers in the figures are: the device comprises a 1-linear displacement sensor calibration device, a 2-linear displacement sensor, a 3-lifting table, a 4-direct current voltage stabilizing source, a 5-digital multimeter, a 6-USB-to-RS 232 serial line and a 7-computer.

Detailed Description

The invention is further described with reference to the following drawings and specific embodiments.

As can be seen from figure 1, the utility model discloses sensor data acquisition system based on LabVIEW and serial communication has increased direct current steady voltage source 4, digital multimeter 5, USB commentaries on classics RS232 serial port line 6 and computer 7 on current displacement sensor calibrating device, and displacement sensor is linear displacement sensor in this embodiment, and computer 7 is notebook computer. In other embodiments the displacement sensor may also be an angular displacement sensor.

In order to reduce installation errors, a lifting table is installed on an existing linear displacement sensor calibration device, the mutual positions of a sensor to be calibrated and the calibration device are adjusted, the linear displacement sensor to be calibrated is fixed on the lifting table through a pressing plate, a power supply +, a power supply-, a signal + and a signal ground in a lead wire of the linear displacement sensor are respectively connected with a direct current voltage stabilizing source 4 and a digital multimeter 5, the digital multimeter 5 is connected with a notebook computer through a USB-to-RS 232 serial port wire 6, LabVIEW data acquisition software is installed in the notebook computer, the digital multimeter 5 is communicated with the LabVIEW data acquisition software, the linear displacement sensor calibration device 1 is moved, and an output electric signal completes data acquisition by clicking a corresponding button of the LabVIEW data acquisition software. The utility model discloses the relevant LabVIEW data acquisition software is prior art, the utility model discloses only improve the collection efficiency and the precision of displacement sensor correction data based on this software.

Mounting the linear displacement sensor on a special linear guide rail by using a tool (the total travel of the guide rail is 800mm, and the precision is +/-3 mu m); the direct current voltage stabilization source inputs voltage, an electric signal value is output by a digital multimeter (Keithley 2000), a guide rail is moved, a corresponding output signal is changed accordingly, the electric signal is sent to LabVIEW data acquisition software in an array form through an RS232 interface, and real-time acquisition and storage are carried out on the electric signal to a PC. When the sensor to be calibrated is an angular displacement sensor, the angular displacement sensor is placed on a high-precision rotary worktable for aligning and leveling (the rotary worktable is 0-360 degrees, and the precision is +/-1'), and when the calibration is carried out, the rotary worktable is rotated, corresponding output signals are changed along with the rotation, and the electric signals are sent to LabVIEW data acquisition software in an array form through an RS232 interface for real-time acquisition and storage to a PC.

Before formal data acquisition, the digital multimeter connected with the linear displacement sensor is used for carrying out front-end data acquisition, and then a Visa Write button of LabVIEW data acquisition software is used for programming a serial port of the digital multimeter, so that communication between the serial port of the digital multimeter and the LabVIEW data acquisition software is completed.

The main program for data acquisition by using LabVIEW data acquisition software adopts a state machine framework and is used for controlling the program to operate in different states and switch among the states. As can be seen from fig. 2, the state machine mainly includes several states of initialization, wait operation, reading test values, and saving files.

A computer port, such as COM1, can be arranged on a LabVIEW data acquisition software interface according to an RS232 interface with a USB; the linear displacement sensor or the angular displacement sensor can be set according to the type of the sensor; the type of the output electric signal can be used for selecting voltage or current; reasonably selecting the number of calibration data points according to the standard requirement; an initialization setting is performed and the measurement interval can be set in the table.

The following describes each step in detail:

initialization

1. Initialization of the digital multimeter:

and sending a serial port instruction to the digital multimeter, and reading a serial port return value returned from the digital multimeter by using a Visa Read button (data reading button) of LabVIEW data acquisition software. Searching corresponding characters or expressions in serial port return values by using a Match Pattern button, checking information returned by the digital multimeter through an instruction to confirm whether the digital multimeter is correctly connected, if the information returned by the digital multimeter is not received or the information is incorrect, jumping out of a digital multimeter initialization error dialog box, performing reconnection, and then performing re-initialization on the digital multimeter until the connection is correct.

2. Initialization of LabVIEW data acquisition software interface:

firstly, selecting a Read Excel button, and reading an Excel sample file; then selecting a Table Clear button to Clear the form, and filling corresponding information set by the measurement into the form, which is similar to generating an empty form; and thirdly, writing the calibration point information into the table according to the calibration standard requirement of the sensor to be calibrated, and finally selecting a CellBG button to set the background color of the corresponding row of the table to be white. The calibration point information includes sensor type, output electrical signal type, calibration interval, etc.

3. Parameter setting

Setting various parameters of a sensor to be calibrated in LabVIEW data acquisition software, wherein the parameters comprise the type of the sensor to be calibrated, the type of an electric signal, display precision, sampling rate, measuring range, calibration point number and the like;

wait for operation

And adopting an event structure to make corresponding event response according to the action event of the button on the interface.

Reading the test value

When the collect button is actuated, the current measurement value is read from the digital multimeter and the value is written to the corresponding location of the form.

Saving files

The data in the table is saved in Excel, and the file is automatically named according to the current saving time. According to the requirements of JJF1305-2011 'calibration specification of linear displacement sensor', the linearity calculation adopts a least square method to calculate a reference equation according to positive and negative stroke calibration values, the formula is very complicated, SLOPE and INTERCEPT values can be conveniently calculated by using a SLOPE function and an interrupt function of an EXCEL table, and therefore the optimal estimation value of each calibration point can be calculated. In this case, technical indexes such as linearity, return error, repeatability, sensitivity and the like can be easily calculated. Likewise, the uncertainty of the measurement can be calculated using the square and root SQRT functions.

Claims (4)

1. The utility model provides a sensor data acquisition system based on LabVIEW and serial communication which characterized in that: the device comprises a displacement sensor calibration device, a direct-current voltage stabilizing source, a digital multimeter, a USB-to-RS 232 serial port line and a computer; the sensor to be calibrated is positioned on the displacement sensor calibration device, the direct-current voltage stabilizing source is connected with the power supply end of the sensor to be calibrated, and the digital multimeter is connected with the signal end of the sensor to be calibrated; two ends of the USB-to-RS 232 serial port line are respectively connected with the digital multimeter and the computer; LabVIEW data acquisition software is installed in the computer, and the digital multimeter is communicated with the LabVIEW data acquisition software and used for acquiring and storing the electric signals output by the sensor to be calibrated.

2. The LabVIEW and serial port communication based sensor data acquisition system of claim 1, wherein: the sensor to be calibrated is a linear displacement sensor or an angular displacement sensor.

3. The LabVIEW and serial port communication based sensor data acquisition system of claim 2, wherein: the calibration device further comprises a lifting table and a pressing plate, wherein the pressing plate is used for fixing the sensor to be calibrated on the lifting table.

4. The LabVIEW and serial port communication based sensor data acquisition system of claim 3, wherein: the digital multimeter is Keithley 2000.

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