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Based LS7266R1 of electronic universal testing machine design

In Electronic Infomation Category: B | on April 13,2011

Abstract: material testing machine and SN74CBTLV3245ADBQR datasheet and other equipment required to measure or control the displacement of the tensile or compression, the general detection of photoelectric rotary encoder position signal, the output quadrature encoder pulse signal. If the position signal detected by other methods, will inevitably lead to the circuit design complexity, reliability decreased. Therefore, the proposed based on LS7266R1 of electronic universal testing machine design. Testing machine is given the controller works, LS7266R1 and SN74CBTLV3245ADBQR price and microcontroller interface hardware design, and SN74CBTLV3245ADBQR suppliers and main software flow chart. Skilfully force sensors, displacement sensors, pressure or mechanical tension state of motion and position coordinates, into a voltage signal and the electrical pulse digital signal for A / D measurement and LS7266R1 count, in order to achieve an independent control or through the completion of material testing PC serial port control command to complete material testing.

Electronic Universal Testing Machine Test Machine is a device that can achieve tensile, compression, peel, tear, and other mechanical properties out of the test and control. The test machine by collecting multi-channel pressure signal, the displacement encoder output pulse signal, and interference suppression, the analog signal amplifying and filtering and isolation transform processing, use the keyboard and display module man-machine interfaces, variable frequency control technology with machine breakpoint stop control, constant load control, constant stress control, positioning shift control, constant strain (elongation) control, power to maintain control, automatic return to control, limit control, multi-condition testing and other functions. And for the realization of the displacement measurement and positioning shift control, presents a photoelectric rotary encoder to capture a special counter LS7266R1 displacement encoder output pulse signal.

1 LS7266R1 Introduction

Axis quadrature phase detector LS7266R1 is a low cost, ultra high-precision, 24-bit dual-channel quadrature counter, programmable counter 4 way, 3 way and 1 quadrature quadrature method of non- , counting accuracy, with X and Y dual-channel count, each count up to 24-bit length, and has a binary / decimal count of two programmable way. It is particularly important function of the direction signs, measuring 2-way (X, Y) equal to the size of the encoder, but the direction of case 2, when the 2-way (X, Y) S symbol for the encoder the same, that the displacement positive direction; when the S symbol for the opposite, that displacement is the opposite direction. With this feature you can convert photoelectric rotary encoder on the electronic universal testing machine in tensile, compression, displacement of plus or minus the value of the implementation of the direction of displacement value judgments. In addition, 3 quadrature mode, the encoder of each channel can achieve 8-bit independent programmable digital filtering functions. Function of its internal register set can be found in the data LS7266R 1.

2 photoelectric rotary encoder

Photoelectric rotary encoder, also known as photoelectric angular position sensor, a binary code output cycle absolute photoelectric shaft encoder and output single or the two 90 phase difference pulse signal incremental photoelectric photoelectric shaft encoder device 3. This selection ZSP3.812-003G-3600BZ-type incremental photoelectric encoder, a complete revolution of the optical encoder with cable side out, 3 600 p / r, wide voltage 7 ~ 24 V, complementary output, integrated module with small size, low price, non-contact and so on. It is a set of optical, mechanical, electrical as one of the precision digital angle measurement device, which the shaft angle digital information into electrical pulse signal, such as through LS7266R1 counter connected with the microcontroller enables real-time dynamic measurement and automatic control.

3 Electronic Universal Testing Machine Figure 1 shows the test machine

machine appearance. The test machine is a base (in place of the single-phase motor and inverter), the control box, power sensors, displacement sensors, and chassis and other components. Control box of the controller is its core, by the force sensor, instrumentation amplifier, multiplexer, A / D measurement constitutes a test machine power unit; by the incremental photoelectric encoder, LS7266R1 counter constitute integral biaxial testing machine capture the displacement encoder output signal. Photoelectric method, the output shaft through the photoelectric conversion of mechanical volume. Geometric displacements into a corresponding electrical pulse signal, resulting in mechanical motion, the change in the location coordinates and other information. CPU Based on the above information, the D / A converter output control to achieve frequency conversion technology and servo control technology, to adjust or start and stop the motor, the speed of adjustment to achieve motor control, displacement control, force to maintain control and other functions; use of algorithms implementation phases of the power sensor calibration, unit conversion, a variety of protection to address the zero drift, ensure system reliability and stability. Human-machine interface to facilitate testing, the system function more cost-effective.

Figure 1 Tester machine

4 LS7266R1 application

4.1 Hardware Design

Figure 2 LS7266R1 in electronic universal testing machine in the block diagram of the hardware design. Winbond W78E58B using high-performance microcontroller, 24-bit ADC7710 converter, 24-bit DAC1210 converter, 24-bit LS7266R1 counter, 8 KB Flash RAM memory 28C64, built-in lithium-ion battery DS12887 clock, serial interface chip MAX232, with a view gate non-volatile memory X25045 a dog and so on. Through the three-bus (data, address, control) and LS7266R1 quadrature counter connected to the output 2 pulse, respectively, X and Y channel count.

Figure 2 Hardware Block Diagram

Figure 2, W77E58B 80C51 series microcontroller, 40 pin, 256 bytes of RAM and 36 kB of Flash EPROM flash memory can be programmed to write several times, there are two full duplex serial port, There are 12 interrupt sources, execution speed is the standard 1.5 to 3 times 8051. AD7710 using - conversion technique to realize up to 24 bits of no missing code performance, 0.001 5% nonlinearity. There are programmable gain controller and digital filter processors. Is a low frequency measurement applications for a complete analog front end, can be directly received from the strain gauge or sensor in the low-level signals, and generates a serial digital output. DAC1220 is a process control applications for low-power D / A converter. It uses the - conversion technology, a 20-bit linear conversion. Through the built-in full-scale, zero and linearity correction register, you can automatically calibrate the function to ensure the accuracy of the conversion. 28C64RAM: 8K bytes of Flash RAM memory, data can be stored for a long MAX232 RS-232 communications standard devices can be connected to two pairs of transmit / receive line, the UARTs RXD and TXD ended TTL / CMOS levels into RS-232 level . X25045 is the serial non-volatile memory, with a watchdog function can be used to monitor the microcontroller is functioning, and also offers on-reset, save the parameters, voltage monitoring function. DS12887 clock for the parallel interface chip, containing lithium batteries, can save 100-year calendar clock for data updates every minute.

4.2 system software design

Main software flow chart in Figure 3. The main system software, including serial port initialization, LCD initialization, 24 AD771O initialization, LS7266R1 initialization, the value of reading 24-bit AD7710, 24-bit LS7266R1 counter value reading, computing, processing, display and keypad scanning procedures.

main software flow chart in Figure 3

4.3 interface software design

LS7266R1 in electronic universal testing machine applications, we must first initialize LS7266R1 settings, initial setup process is this: write control word to XIOR or YIOR register, control the A / B input stop work; write control word to XRID or YRLD register, reset BT, CT, CPT, S, BP status value; write control word to XBLD or YRLD register, reset the value of E, and CNTR state; written to counter initial value # 00H to XPR2 XPR1XPR0 or YPR2 YPR1 YPR0 pre-register, the initial value to the counter CNTR; write control word to XIDR or YIDR register, enable INDEX bit; write control word to XCMR or YCMR register Select X1, Normal count work; write control word to XIOR or YIOR register, control A / B input starts work. Second, the process of reading LS7266R1 counter is this: write control word to XBLD or YRLD register pointer BP is reset, read XFLAG or YFLAG flag register; write control word to XRLD or YRLD register, send XCNTR or YCNTR counter value to XOL or YOL output register, output register read XOL or YOL value to W78E58B RAM within the microcontroller unit, and then computing.

5 test machine PC software design

Material testing machine system with a powerful PC software, materials testing can be realized independently or through the PC serial port control command to complete the materials testing control in two ways. PC VB using object-oriented programming language designed to achieve the test product data, the data show, the curve shows that the report set to print, a variety of test methods, data analysis, another module, printing, testing, statistics, unit switching ( F / X), sensor channel switch, the line machine platform, machine stops, the audience line machine, return to zero displacement, multi-correction functions. PC software can be realized through the machine speed and displacement control, real-time displays the current pressure data, displacement data, peak force and displacement. Breakpoint stop control, constant load control, positioning shift control, power to maintain control, automatic control and return control measurement. Function of a statistical inquiry, memory, last 10 times / sample test results were the same batch (force, displacement), statistics, query the results of each test. Testing machine software features one screen shown in Figure 4.

Figure Figure 4 test machine software

6 Conclusion This structural principle

start from LS7266R1, about features of the chip, the use of methods. Key to LS7266R1 and SCM W78E58B hardware interface circuit and software program design process, for example, about LS7266R1 in Electronic Universal Testing Machine method. Innovation of this paper is to skillfully force sensors, displacement sensors, pressure or mechanical motion state of tension and position coordinates, into a voltage signal and the electrical pulse digital signal for A / D measurement and LS7266R1 count, enabling the electronic Universal testing machine measurement and control. Materials testing to achieve independently or through a PC serial port control command to complete the materials testing control.

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