Brief introduction
Board Test System (PTS, Pcb Test System) refers to the control of the computer can automatically complete the excitation , measurement, data processing, display or output the test results collectively a class system. circuit board test for the completion of the test Pcb performance testing , based on the analysis of the test results , diagnosis and fault location can also be expanded into a diagnostic system . Circuit board test system with high-speed, high-precision , multi-function , multi-parameter and wide measurement range and many other features . The computer technology, microelectronics , electronic measurement technology are the three cornerstones to build a circuit board testing.
Classification
Circuit board test by test subjects were divided into : a dedicated circuit board test systems and circuit board test systems.
Dedicated circuit board test system: PCB testing specific task or a specific test object and the development of test systems. Often named by the test object , such as the BTS control panel testing, remote control circuit board testing , power meter circuit board testing.
Universal circuit board test : a test for certain areas and developed PCB circuit board test systems. The C3065 series such as Teradyne board test machine can complete space laboratory tests Nano- circuit board , and HBM's SmartA2000 circuit board test systems belong to the scope of universal circuit board testing .
Composition
Board Test System (PTS) consists of three major components: tester , test software, test procedures .
Test machine: used to complete all the testing tasks appropriate operating system hardware and software in general. Such as cabinets, a variety of test equipment, measurement and control computers are.
Test software: and tested circuit board and test tasks are closely related to special test equipment and special test software in general. Such as device-specific test software components dedicated test interface adapter ( including interface devices, fasteners and cables ), tested various files needed for the board.
Testing procedures: required to develop a series of test software tools referred to testing procedures, also known as the serial configuration files, such as ARINC's foreign SMAR manager, domestic oriental beacon GPTE configuration set, Houde company HOUDECOM sequence manager , are all testing procedures.
Abroad from the beginning of the 20th century began to grind circuit board test systems, initially mainly used in the military field. According to statistics, after the use of circuit board test, to test the efficiency of the equipment can make more than 10 times, cost savings in its whole life cycle of more than 20 %. In view of the circuit board test for excellence in production and maintenance functions, the developed countries in the world have invested their own circuit board test technologies that facilitate the rapid development of this industry. Emerging object-oriented technology , has also been broad application , which directly promote the birth of a new language ATLAS, CASS has been in the United States, RADA France's ATEC, Israel has been engineering applications.
Architecture
1, measurement and control computer
Early automatic test system to use more minicomputers and workstations , along with a substantial increase in performance of a modern PC, minicomputer performance has been far higher than before, and now tend to adopt widely popular modern PC ( also known as plug-in processor ) this facilitates the use of the latest achievements in the development of computer technology , easy to update. To meet the requirements of miniaturization and portable test system circuit board testing, also developed based on VXI bus and PXI embedded PC, can be inserted directly VXI chassis or PXI chassis, so that the test system more compact, more compact form factor. When using plug-in processor integrated system, you can use MXI-VXI or MXI-PXI bus, GPIB bus, IEEE-1394 ( commonly known as FireWire ) bus , USB through a variety of ways to communicate with VXI or PXI chassis serial bus, etc., these types of communication methods have advantages and disadvantages, the choice of the specific factors to be considered cost of communication, data transmission rate, and their respective physical and mechanical properties.
2, the operating system
Operating system available for many of the circuit board test selection , such as UNIX, OS, Windows, Solaris , etc., select the operating system is limited by the hardware device support, technical level program staff , and the popularity of the operating system features , such as the operating system itself many other factors, it tends to be adopted widely popular Windows operating system.
3, bus technology
Circuit board test technology development and the development of instrument control bus is always closely related instrument control buses updates promote updated every circuit board test technology. Currently there GPIB instrument control bus bus, VXI and PXI bus three, which are in turn the development process appeared bus technology represents the development process of circuit board test technology. GPIB bus is the early stage of the instrument interface control bus , used now common on desktop machines, using a large volume of the integrated system bus, the data transfer rate is low ( maximum data transfer rate of 1MB / s) on the same system bus and up even 15 instruments. VXI bus is a computer bus VME industrial computer bus extension to the formation of the instrument, using the bus system volume between the GPIB bus system and the communication speed between PXI bus system, the cost is the highest. PXI bus is a Compact PCI Industrial Computer bus to the bus after the instrument is extended to form a computer, using the volume of the smallest of the bus system, the communication rate is relatively high, and the cost center. PXI PCI bus directly to the use of computer technology achievements bus , absorbing the advantages of VXI bus. Overall , VXI and PXI bus instrument instrument performance is quite high equipment costs VXI bus, PXI bus instrument is rapidly developing process, and now use more integrated PXI bus system.
4, the interface technology
Currently for testing different circuit board has a variety of common interface standards emerge. Such as ARINC, CASS military field , the field of aviation MATE other commercial areas. ARINC Interface widely used in the commercial area of the current rapid development, instruction and complete , but higher costs for large , medium-sized enterprises and institutions use.
Currently the board has been tested to universal, standardized , open, modular , serialized direction, but also to keep pace with technological developments related to high-tech to keep pace , taking advantage of the results achieved in the industrial sector has become interdisciplinary , interdisciplinary , multi-disciplinary an integrated technical disciplines.
PCB circuit board tester functions and applications
First, PCB circuit board tester main function
The basic principles of digital functional test chip is to detect and record the input of the chip / output state and the state of its recording state truth table compares the standard , in order to determine the correct function of the test chip .
Circuit tester using online testing techniques that can be used online or offline test a variety of small and medium -scale common failure analysis of integrated circuit chips , testing analog, digital devices V / I characteristic .
The state of the digital chip testing circuit boards each digital device , after power has features three states: the logic state of each pin ( power, ground , high impedance , signal, etc. ) , the connection between the relationship pin input logical relationship between the outputs . When the device fails, its state characteristics are generally required to change. Tester able to state the good characteristics of each circuit board IC devices extracted, stored in the database of the computer, and then with the same faulty circuit board compares to accurately identify the fault location.VI characteristics of the test function test analysis based on simulation technology based on the characteristics of the analysis can be used to test analog, digital , special devices, and large-scale programmable devices , ultra- large-scale devices. Tester probes or test clip by automatically extracting characteristic curve of the measured points out , displayed on a computer screen , and finally into the computer. Typical feed fault diagnosis will be measured to a standard curve and curve VI for comparison stored in advance , and then find fault .
Since node voltage tester test object includes not only a digital circuit device , including a large number of analog circuit components , to further enhance the scope of the tester , the tester used in the node voltage testing techniques . By applying the operating voltage of the measured object , the value is read by the computer in response to the test voltage node and create a standard test information database for the operator to analyze and determine the fault location.
In addition to these other functional tester main function, but also have electronic manuals, test development , system self- test and other auxiliary functions .
Second, the composition of the tester
1 , the hardware module
Tester by a portable computer , microcontroller test platform and test analysis software composition. SCM test platform which completed the data collection of the measured object under computer control . Each part functions and are described as follows:Microcontroller circuit mainly for data acquisition, control , command processing , and computer data exchange. In the tester design using the MCS-51 series of 8031 , the choice of 2764 as an expansion ROM, 6264 as an extension of RAM. Decoding chip circuit as 74LS138. Serial communication with the computer, using MCl488 and mutual MC1489 RS-232C level converter with TTL levels. MCU system clock frequency selection 6MHz crystal, communication baud rate selection of 2400, SCM work three serial communication. Timer T1 is set to mode 2 . Set SMOD = 1, the time constant F3H. Bus Driver microcontroller bus expansion to improve drive capability , selection 74LS244, 74LS245 line driver.
The main drive control circuit to complete the testing process TTL, CMOS test threshold control , the choice of four heavy SPST ( single pole single throw ) DG211 analog switch , switch control over to the decoding circuit and 74LS373 latch. To ensure that the boot is normally open when the DG211 (OFF) state, control lines increased pull-up resistor (10kΩ). Test drive circuit chip test applied to the measured input signal, the input signal is a miniature relay control, test signal 74ACT244 generated by the data buffer. To ensure that the input current to meet the design requirements, using 4-way parallel . To prevent damage to the device , increasing the LC network of high-current buffer , and diode protection circuit design.
Reads the data acquisition circuit in response to the measured output of the chip , LM393 dual voltage comparator output signal. Its low power consumption, high precision comparison , and is compatible with TTL logic. LM393 output data latch 74LS373 associated , controlled by the microcontroller reads comparative data.
Driving voltage D / A circuit is completed during testing VI stepped voltage output. 8- bit parallel D / A converter MC1408. Chip supply voltage of +5 V,-12V two kinds. Constant reference voltage provided by the voltage source TL431. Output Select bipolar output by two LM348 amplifier circuit is completed .
Current conversion acquisition A/D circuit test point current implementation of data collection. And a load resistor in the circuit of the differential amplifier circuit LM343 voltage follower of the test points, the test point the current value converted into voltage A / D converting circuit can handle. Selection of eight successive comparison AD7574 high-speed A / D conversion circuit . Conversion time 15μS, single +5 V supply. Selection of a reference voltage VREF =-8V. Input voltage range of 0 ~ + | VREF |. RD program control chip client generates a negative pulse can start A / D conversion.
2, a software module
The portable tester is controlled by the host computer via serial port , single-chip platform to complete the test stimulus control , data acquisition , etc., all of the data analysis and processing and command and control is done by a portable host computer . Test software package by the master software, data communications software , offline test software, test software online features , online testing software , VI characteristics of the test software , the node voltage test software, electronic manuals, test development software, system software , and several self-test The main module.
Third, the circuit online testing technology
To ensure that the device on the circuit board functional test , you must force the logic level device drivers , each driver must be able to absorb foot or output sufficient current . According to the international protection standards document ( 00-53/1 ) recommended driver safety standards , the maximum drive current tester is designed to 240mA, the test time is less than 200ms. Through the experiment, the substantially better able to isolate the device under test , but also to ensure the security of the device under test .
1, online test principle
The basic principle of the test line is a printed circuit board tester to the chip under test to provide input excitation , and collect output responses automatically recording the measured values and states under computer control chip , the computer records the value of all the state and standard state truth table , thereby judging the fault condition of the measured object .
2, the driving test technology
After driving test technology is mainly used for online testing of digital circuits . Its essence is in the input stage of the DUT ( pre- driver IC output stage ) sink or large transient currents , forcing its potential becomes high on demand or low , to applied testing of the device under test online incentive purposes.
About PCBway
Since 2003 PCBWAY has been the leading PCB quick turn manufacturer specializing in both Prototype and Production quantities, Initially produced single-sided and double-sided printed circuit boards for the consumer electronics market. PCBWAY is ranked among the top 4 board fabricators in asia and is well-known for its expedited turn time capabilities and its reliable best on-time shipping record.
Today, we have over 450 operators with high modern facilities to manufacture multi-layer PCB up to 12 layers. Backing up with a group of professional engineers, and well established quality system. PCBWay has grown to become a major PCB manufacturer in Asia to serve in diverse customers base such as electronics appliance, communication, educational electronics, power supplies, Automationsetc.
Our mission is to become one of leading PCB manufacturer that provide in high quality product with total customer satisfaction.
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