Design of network virtual oscilloscope system based on virtual instrument technology and data acquisition network

With the rapid development of semiconductor and software technology, automotive electronics accounts for an increasing proportion of the automotive industry. From the realization of car comfort to stability and even safety, automotive electronic products play a vital role and are playing an increasingly wider role. Automotive electronics manufacturers are also facing huge market challenges - improving product quality, accelerating production cycles, reducing production costs, etc.

Under such conditions, the requirements for test equipment for automotive electronic products are increasing day by day, which are mainly reflected in the following aspects.

Complex testing requirements

The proportion of automotive electronic products in the vehicle system and the functions they implement are constantly increasing, requiring them to have rich functions; with the development of body networks based on CAN, K-Line, LIN and other buses, it is also necessary to realize the integration of individual devices and the entire vehicle. Reliable real-time communication between networks. This requires automotive electronic products to undergo complex functional and parameter testing processes before leaving the factory to ensure that the products meet the many functional and quality requirements stipulated by the car manufacturer.

Strict quality management process

In addition to being able to implement testing functions, testing equipment also needs to save test data, provide online analysis of test data, and be able to easily perform production process statistics (SPC) based on this, such as measurement system analysis (MSA) and process capability index (Cpk), etc. , thus serving as a data source for enterprise quality management.

Development and testing cycle

At present, the cycle for automobile manufacturers to launch new models is getting shorter and shorter to meet the evolving market requirements. For automotive electronic products designed abroad and produced domestically, domestic manufacturers need to establish a complete test line in a short time; for automotive electronic products designed independently in China, the test line is often required to not only perform pre-factory testing, but also Undertake part of the design verification task, so the test system must be implemented during the product development stage. At the same time, changes in test equipment due to product improvements need to be considered in advance.

Strict time requirements are also reflected in improving test efficiency. For mass-produced products, it is difficult to meet time and quality requirements using traditional testing equipment with single functions and manual operation by operators. Therefore, the use of automated testing equipment has become an indispensable condition for improving product quality and output.

Cost Control

Automotive electronics manufacturers often need to produce multiple models of products with similar testing requirements, which requires test equipment to be reusable. Multiple products can simply share the same test line to achieve the purpose of reducing production costs. At the same time, It also reduces equipment maintenance expenses.

If imported testing equipment is completely used, the equipment introduction and maintenance costs will be high and the maintenance cycle will be long. More and more manufacturers are considering localizing imported equipment, using local suppliers or developing and maintaining it themselves.

From the above, it can be seen that in the testing of automotive electronic products, the testing equipment used is a software and hardware platform that needs to be quickly and flexibly customized according to the different products under test, can provide rich testing functions, and facilitates rapid development and maintenance by local engineers. .

testing platform

In response to the above application requirements, this article introduces an automotive electronics test platform based on virtual instrument technology, which can greatly facilitate manufacturers to test automotive electronic products.

Figure 1 Composition of automotive electronics test platform

As shown in Figure 1, the test platform is built based on virtual instrument technology and consists of two parts - software and hardware. The hardware uses National Instruments (NI) PXI modular instrument; the software is developed using NI's LabVIEW graphical programming language and TestStand test management software.

Hardware composition

PXI is a modular instrument platform tailor-made for industrial data acquisition and automation applications. It has outstanding features such as system modularity, easy integration, easy loading, unloading and connection, as well as the convenience of improving equipment synchronization and triggering accuracy.

At the same time, PXI modular instruments have a wealth of products. For example, the PXI modules produced by NI are suitable for various analog and digital signal acquisition, conditioning, signal multiplexing and matrix connection control, and various Bus interface, radio frequency and arbitrary signal generator, etc. It can provide automotive electronics manufacturers with a wide range of choices.

Figure 2 shows a typical set of PXI modular instruments for automotive electronic product testing, which includes a Pentium CPU-based PXI controller, multiple current and voltage circuits composed of digital multimeters, multiplex switches and matrix switches. Test systems, RF signal generators for generating car radio station signals, car radio audio analyzers and other equipment. In order to achieve automated testing, automotive electronics manufacturers usually use the bus of the product itself, such as CAN, K-Line, etc., to open specific control instructions for product status control, thus eliminating the need for manual intervention. Therefore, these modular instruments usually include a bus controller (such as CAN, K-Line, LIN controller, etc.). In addition, a DIO card with wide voltage input and output and optical isolation is usually configured for timing synchronization and fixture control with the automated production line.

Figure 2 Typical configuration of PXI modular instrumentation

The example in Figure 2 includes various commonly used automotive electronic product testing instruments. In most applications, the above-mentioned modular instruments can be customized, and some of them can be used to implement functions such as car radios (including VCD/DVD/navigation), instrument panels, driving recorders, HVAC (Heating, Ventilation and Air Conditioning) and other products in the PCB and complete machine state function and parameter testing.

Software composition

As shown in Figure 3, the software part of the automotive electronics test platform consists of product driver, test equipment driver, test project implementation, test sequence (Test Sequence) and user customized programs (such as user operation interface, test database management software), etc. Partially composed.

Product driver - used to implement program control of the product under test, usually controlled by various bus methods (such as CAN, K-Line, serial port, etc.). In order to achieve the purpose of testing without manually setting the product status. For a specific type of product, the parameters that need to be controlled are usually uniform and independent of the model. For example, for the audio test of car radios, regardless of the model, the parameters that need to be controlled usually include volume, band, tuning frequency, sound effect control, etc. This ensures that when developing test software for new models of products, there is no need to modify the functions that call them, and only need to re-develop a set of radio control programs that conform to the predefined interface types.

Figure 3 Software structure of automotive electronics test platform

Test equipment driver - mainly refers to the driver of PXI modular instruments, which is used to ensure the normal operation of the instrument and provide application program interfaces (APIs) to developers. This part does not need to be developed by users. The manufacturers of PXI modular instruments will provide corresponding drivers with the hardware. They usually also have a hardware management environment with a simple interface and easy operation (such as NI's MAX). Through this hardware management environment, users do not need to Programming can realize hardware self-test, manual testing, hardware configuration and other functions.

The test project implementation part is the combination of product driver and test device driver. Automotive electronics manufacturers have specific test specifications for different products, and the test specifications for the same type of products are usually the same. Once the development is completed according to the manufacturer's requirements, there is no need or little change in the execution program of the test project when building a test line for similar products.

Test sequence - according to all the manufacturer's test requirements, the test items are combined to form a test sequence. In this platform, the test sequence is represented as a .seq file (TestStand file). All data collection, analysis, and recording functions are implemented in this test sequence.

User-customized programs - including user interface and test database management software, etc. In this test platform, the user operation interface and test database management software serve as a common component and can be applied to the test lines of various products without any modification.

The software platform has the following features:

* The same testing software platform can test different models of similar products.

Since the test content and test methods of similar products are usually similar, the test project implementation part of the software only needs to be configured accordingly for different products, and can be used for all test projects with the same test method, without the user having to rewrite the code.