Thermotron Product Test Solutions Creates a Portable Test Station for ECU Field Diagnostics

Author(s):
Paul Jablonski - Thermotron Product Test Solutions
Wes Haveman - Thermotron Product Test Solutions

Industry:
Automotive

Products:
LabVIEW

The Challenge:
Designing and developing a portable, automated test station for a single engine control unit (ECU) that executes in a quick and comprehensive manner.

The Solution:
Constructing a portable system with a front panel containing 138 test points, accessible via banana jack shorting pairs for monitoring and injecting signals to product pins, with a 1U industrial PC with a retractable, 1U keyboard/monitor, three custom Thermotron load circuit boards, an automotive communications unit, a 13.5 V DC power supply, a DC-to-AC inverter residing inside the unit, and National Instruments M Series data acquisition with custom software written in NI LabVIEW.

Advanced Testing Capability Requirements

The customer required a comprehensive test system capable of adequately assessing ECU status and functionality. They needed the test system to be turnkey, expeditious, and portable while still maintaining advanced security features such as password-protection.

The customer contacted Thermotron Industries to provide a complete testing requirement solution. Long recognized as a premier environmental chamber supplier, Thermotron also provides complete test system integration capabilities through the Product Test Solutions group.

Solution Hardware

The Thermotron test system contains sophisticated communication and measurement equipment including custom Thermotron load and signal conditioning assemblies. These circuit boards simulate normal ECU operating conditions, thereby increasing test accuracy. All equipment is enclosed in a stainless steel chassis specially designed for transportability.

We designed the test system cabinet to minimize tester size and weight but not at the expense of functionality and performance. The top of the system is angled for easy access and signal processing and monitoring test point display. To further promote portability, we can supply power either through a typical 120 V AC line or by an external 12 V battery connection.

We designed and produced custom circuit boards for test system use. Three separate but integrated boards provide waveforms, signals, and loads to the product. They handle communication, high-side, low-side, digital input and output lines, and multiplexing. To handle the data acquisition and waveform generation, the NI PCI-6229 M Series DAQ device was a perfect fit in the lone PCI slot available in the rack-mount PC to process the full array of pins.

The test system is equipped to use three types of communications – SCI, J1850, and CAN. Two PC COM ports handle engine and transmission SCI Rx/Tx lines, while an automotive communications protocol manages J1850 and CAN communications.

Solution Software

We wrote the custom Thermotron software that controls the test system using NI LabVIEW 7.1 with C dll function calls and the NI-DAQmx driver software. The program flashes the ECU with diagnostic code, reads memory locations, and runs sequenced tests. These test sequences are comprised of a set of test channels, each of which checks the functionality of an individual product pin. The program runs the test sequence automatically; the user can set breakpoints at each test channel, if desired. The user can make a measurement at the exposed test points or inject a different signal into the product. Users can flash, check memory, and run test sequences, but only privileged users authenticated by a login prompt can edit and create new sequences. Each test channel has user-configurable pass or fail upper and lower limits, along with the number of setpoints through which to sequence. For instance, the user may want to verify that a particular analog input channel works properly at several different voltages, or measure a digital line at both its on and off states. In the last step, the software records all data and saves it to a file.

Using NI LabVIEW and M Series DAQ allowed us to design the software to accommodate several types of ECUs. We can configure test sequences, pass and fail limits, setpoints per test channel, and even the communication protocol messages easily, without updating and recompiling the software. These features bring increased diagnostic capabilities and mean easy adaptation for future products.

Complete Turnkey Solution Creation

This system is an example of how Thermotron Product Test Solutions works with the customer to create a complete turnkey test system solution. By using National Instruments hardware and software, Thermotron Product Test Solution is able to create a cost-effective tester that automates a previously labor-intensive process in a way that can be expanded for future requirements.

For more information, contact:

Steven Petersen

Inside Sales Engineer

Product Test Solutions, Thermotron Industries

Tel: (616) 393-4580

Fax: (616) 392-5643

E-mail: spetersen@thermotron.com

 

Browse All Case Studies »