Portable vehicle diagnostic systems provide flexible testing and improved process verification in automotive assembly plants when combined with wireless networks.

A portable test system not only provides process flexibility, but also reduces installation and retooling costs. For a test system to provide process verification, the tool must hvae connedtivity to the plant information system to determine vehicle build options.

The key to deploying an effective portable diagnostic system is to use a wireless network to provide plant Information System (IS) connectivity.

Wireless Networking Technology

In June 1995, Dynetics' Industrial Automation delivered a portable electrical test system for the 1996 Ford Taurus at the Atlanta Assembly Plant. This system was one of the first of its kind to use wireless networking technology and a portable test unit to provde online process verification at an assembly plant.

The system provided diagnostic tests on electronic modules such as the integrated airbag module, the anti-lock brakes system, the remote climate control and the generic electronic module. These tests were previously conducted at the fixed tester located after the end-of-line, but increased test time forced Ford to consider alternatives.

Dynetics provided a solution that consisted of portable test units and wireless print stations linked to a work cell controller over a wireless network. It enables Ford to meet the required production rate as tests are performed as the vehicle moves down the line.

The portable test unit is based on a portable PC, repackaged with the electronics necessary to communicate with the electronic control units using industry standard protocols. These features include:

• Rugged PC-based portable test unit
• 2.4 GHz spread spectrum interface
• TCP/IP network communications
• J1850 and ISO 9141 automotive protocol interfaces
• 16-way diagnostic cable (for OBD-II connector)
• Bar code scanner for vehicle identification
• Wireless software downloads

the work cell controller (WCC) is a plant floor serfver for the test system. It acts as a gateway to the plant broadcast system, and provides quality analysis reports of the test results.

Transactions from the test units are processed in real time and data is stored in databases providing instant access to information for the line supervisors. Real-time reporting enables line personnel to detect problems earlier and react more quickly.

The wireless print stations consist of a pedestal-mounted PC with a wireless network card and a slip printer. They are located in test areas to provide printed tickets with the test results including fault codes and descriptions.

Simple Operation

System operation is simple and little training is needed. The operator scans the vehilce identification number and the test unit requests the vehicle build option information from the WCC.

The operator then places the unit in the vehicle and connects the cable to the OBD-II connector under the dash. Then the diagnostic testing is complete, the unit sends the results to the WCC and the print station. The operator places the printed ticket in the car.

Dynetics continues to develop software and hardware to expand the capabilities of in-plant test systems. Portable diagnostic systems can be used for a variety of testing applications such as visual inspections, electronic module comunications and diagnostics, and electrical current measurements. They have also been used for process operations such as programming keyless entry systems and loading parameters into the modules.