NI provides products for Boeing 787 avionics equipment testing

Korry Electronics uses the power of virtual instrumentation to design the control panel used on the Boeing 787 Dreamliner

"We can quickly develop new test software using LabVIEW and have unlimited control over CAN bus data. The PXI-CAN card is very easy to configure and has a high degree of operational reliability."

- Allen Cutler, Korry Electronics

challenge:

Develop a CAN bus test system to interact with the control panel of intelligent avionics equipment, display switch status, control panel lighting functions, and report panel status data such as part number and serial number.

Solution:

Using NI's LabVIEW for rapid development, the NI PXI-CAN board is equipped with a ready-to-use NI LabVIEW driver library, and NI TestStand is used to manage production test steps and automatically generate reports.

author:

Allen Cutler - Korry Electronics

We at Korry Electronics needed a solution to test a range of control panels for the flight consoles of the new Boeing 787 aircraft. We needed to meet the aggressive timeline for the project - just 16 months, shorter than any previous Boeing aircraft development program. The core of the 787 system uses an open architecture, so it will be simpler than existing aircraft and provide improved functionality. One example is the condition monitoring system, which will monitor itself and report maintenance needs to a computer system on the ground.

In the aviation industry, control panel suppliers are looking for low-cost alternatives to the ARINC-429 bus, and due to the need for high-speed bus bandwidth and data payload, they are gradually turning to CAN-based solutions. We need to communicate with and monitor multiple CAN buses on each device under test to obtain correct CAN data and send control data to adjust lighting and set other panel functions. We chose NI's LabVIEW, which is compatible with NI PXI-CAN boards and easy-to-use NI LabVIEW driver libraries, and can be quickly developed according to project requirements.

The control panel sends discrete digital switch data and a unique data word that represents the position of each switch. For control panels that contain rotary potentiometers and encoders, the data value will increase or decrease depending on the direction of rotation. The CAN data word sets the lighting level of all control panels and uses switch commands to set the control panel indicators. In production testing, we test one control panel at a time. For quality testing, we configure the NI PXI test system to test multiple control panels simultaneously over the CAN bus.

Hardware and system structure

The test system hardware consists of two NI PXI-8461/2 CAN interfaces installed in a PXI chassis along with multiple relay boards, power supplies, and DMM cards. The system can monitor four independent CAN buses and all discrete I/O and DC power simultaneously. Each control panel sends a unique CAN bus ID for use by the LabVIEW program. This allows the test system to simulate a CAN bus data hub used on an aircraft.

The test software was written entirely in LabVIEW, with the NI-CAN driver integrated into a custom subroutine to initialize the CAN port at a specific CAN address and read the CAN bus data frame. We also created a subroutine to compare the received data with the expected data frame. For each CAN bus session, the CAN and object network interfaces are first opened and set, followed by the CAN read operation, and finally the session is closed. For the lighting function, the specified CAN data is sent to the control panel. We also wrote a program to monitor the switch position in real time, while monitoring the CAN data of each panel, and once a change is detected, the timestamp data will be written to the log file.

In production testing, we use NI TestStand to control the test sequence and generate test result reports. The first step is to prompt the operator to set each switch, rotary potentiometer, and encoder to a specified position. The test software panel will graphically display the position of each switch on the UUT. The second step is to create an HTML log file to record the error data during the test. In one scenario, all indicators on the control panel are fully illuminated, allowing the operator to visually check whether the indicators are illuminated correctly. We created a subroutine to send CAN messages to illuminate the control panel, and can use the LabVIEW dial to send CAN data to control the brightness level in real time, from no brightness to full brightness level. In another scenario, the operator clicks on the test software panel to individually command each indicator to light up by sending CAN messages to the control panel.

Conclusion and Outlook

We have successfully developed a series of complex CAN-based control panels for the Boeing 787 aircraft using NI hardware and software. We can quickly develop new test software using LabVIEW and have unlimited control over CAN bus data. The PXI-CAN card is very easy to configure and has a high degree of operational reliability. We will use NI test hardware and software to develop test instruments for those who need to complete development quickly and efficiently in the next few years.