点击图片查看原图
|
|
作者:
Russell Blake - G Systems, LP
产品:
CompactRIO, 实时模块, LabVIEW, FPGA模块
挑战:
Building a rugged, portable, automated tester that soldiers can easily transport and deploy in harsh environmental conditions to ensure their line-replacement units (LRUs) are combat ready.
解决方案:
Creating a compact and durable custom tester using CompactRIO and the LabVIEW FPGA Module for high-channel-count, analog input, and digital I/O to control I2C and serial communications.
"CompactRIO was chosen because of the ease and flexibility of programming along with environmental certifications. "
Creating a compact and durable custom tester using CompactRIO and the LabVIEW FPGA Module for high-channel-count, analog input, and digital I/O to control I2C and serial communications.
The field testing of military units is essential for success in combat. Automating this process reduces errors and time. This paper discusses the automation of a portable military tester.
A defense contractor decided to redesign and automate its test system and chose G Systems, a National Instruments Alliance Partner, to work on the project. The defense contractor’s system consisted of a software application and a separate hardware box with cables. The software application and user interface ran on a laptop with user instructions for the test procedure. The hardware box contained loads and relays, which were connected to the units being tested by the cables. During a typical test, the soldier needed to manually switch relays and measure analog readings with a separate handheld digital multimeter, or perform a self test on the hardware box using shorting plugs. The soldier then had to document the test results.
The new, portable system, designed by G Systems, automates the hardware steps and automatically logs test results, reducing test time and improving accuracy by eliminating error-prone manual tasks. The hardware can be remotely accessed by using a defined command set in the software application that runs on a laptop, which enables the tester to function like a test and measurement instrument.
Industrial and Rugged HardwareThe tester controller was an important consideration when selecting the hardware for the new system. The CompactRIO was chosen because of the ease and flexibility of programming along with environmental certifications. Because of the durability and versatility of the CompactRIO, the G Systems automated tester can operate in harsh and extreme conditions. The tester can be used anywhere with an AC or DC power source and complies with MIL-STD-1275B. The tester is also certified to handle shock and vibration defined by MIL-STD-810E. Due to the complexity and number of cables, the tester includes full self-test capabilities with embedded self-test connectors for all cables. This reduces the need for shorting plugs and provides better self-test coverage.
Software Overview and ArchitectureThe architecture is designed to be flexible and allow for remote communication and monitoring from the test application residing on the laptop.
The CompactRIO has an embedded LabVIEW Real-Time Module, which runs automatically using the built-in LabVIEW Real-Time executable startup feature. It handles all of the tester logic, self-test procedures, logging of results, network communications to the laptop, RS232 serial communications, and interfacing with the LabVIEW FPGA application. The LabVIEW FPGA application controls all the analog input and digital I/O functionality.
G Systems provided a DLL with a defined command set so that the test application could communicate with the portable tester. The DLL handles all network communications between the laptop and the CompactRIO.
The debugging and monitoring of the software and hardware was simplified using a reusable and efficient software component called the G`` Systems Event Tracker. This software component time stamps event messages to a millisecond resolution, logs event messages to the disk, and displays live event messages. These messages can be viewed from the G Systems Event Viewer application or incorporated into a custom application using the G Systems Event Viewer control.
Custom Hardware ControlAs described earlier, the previous system required the user to manually switch relays. Using the reconfigurable LabVIEW FPGA Module and a CompactRIO digital I/O module, G Systems developed a scalable, cost-effective solution for automating the process. The G Systems approach uses two digital inputs on the NI 9401 to generate the data and clock lines to control an I2C compatible 2-wire serial interface digital I/O chip. Because the data line from the chip is also connected to a digital input on the NI 9401, the software can poll the state of the digital I/O chip.
G Systems created a reusable driver using the LabVIEW FPGA Module to implement the I2C communications protocol. A modular chip-specific driver was developed using the LabVIEW Real-Time Module and the LabVIEW FPGA Read/Write Control function. The main LabVIEW Real-Time application uses the modular chip-specific driver to communicate with a custom PCB board designed in-house to control and monitor up to 56 relays. However, by adding additional I2C chips, the hardware can be expanded to control up to 448 relays through the same 2-wire serial interface.
G Systems designed and built a rugged, portable automated tester with an embedded controller, resulting in improved test accuracy, repeatability, and time savings.