Conformance testing - vital for open networks and a key factor in the growth of DeviceNet

Citation

(2000), "Conformance testing - vital for open networks and a key factor in the growth of DeviceNet", Assembly Automation, Vol. 20 No. 3. https://doi.org/10.1108/aa.2000.03320cab.004

Conformance testing - vital for open networks and a key factor in the growth of DeviceNet

Conformance testing - vital for open networks and a key factor in the growth of DeviceNet

Keywords: Testing, Networks, DeviceNet

The ability to purchase devices from a variety of vendors is a key feature of open networks. The challenge is that the ability to purchase does not always translate into the ability to use. A lack of interoperability and interchangeability can slam the door on an open solution.

To meet end users' expectations, the Open DeviceNet Vendor Association (ODVA) established a conformance test in 1996. As a result vendors are able to submit products to one of three independent laboratories and test their compliance with the DeviceNet specifications. Once the device passes, the vendors earn the right to label and sell the products with the Conformance Tested service mark (see Plate 2).

The key element of the conformance test is that the DeviceNet specification must be strictly followed. This ensures the interoperability of multi-vendor products such as sensors, actuators and controllers. It also makes things easier for System Integrators and increases end-user confidence. An up to date list of conformance tested products is available on the ODVA Web site (www.odva.com).

Plate 2Conformance testing - vital for open networks and a key factor in the growth of DeviceNet

Features covered in the interoperability tests are filtering, multiple access, selectability, session timer, high bus load, hot swapping, distributability and repeatability.

Clearly, conformance testing is a big issue. Gary Workman, GM North American Car Group, Controls, Robotics and Welding, said:

General Motors insists that all the DeviceNet products it purchases pass the ODVA conformance test.

Josephine Robinson, Manufacturing Engineer at Ford Halewood, explains why Ford wanted to replace its gearbox assembly line:

The original assembly line was built in 1978 and in its time met both manufacturing and customer needs but, as car design and manufacturing techniques have changed, the line became outdated in terms of customer and operator needs.

Ford also recognised the need to increase capacity and quality whilst reducing costs in an increasingly competitive market.

The solution involved four major DeviceNet competing vendors, Cutler Hammer, Rockwell, Festo, and Wago, but all the devices were required to be conformance tested.

We asked for vendors' views:

The trend in the marketplace is for end users to demand performance guarantees from Fieldbus solutions - having conformance tested product is a key part of ensuring that we meet those end user requirements (Mark Daniels, Product Manager, Rockwell Automation).

If we don't have Conformance tested products, increasingly we wouldn't make the approved vendors list (Andy MacBeth, Technical Director, HM Computing).

More than 80 per cent of vendors that come to the Warwick European Test Lab are there at the demand of their customers (Kiah Hion Tang, Research Fellow, University of Warwick).

There can be no doubt as to the importance of conformance testing. The significance of treating it seriously can be measured in the fact that ODVA membership has increased ten-fold over the last five years and the number of installed DeviceNet nodes is increasing at over 250 per cent per year.

For further information, please contact: Richard McLaughlin, Chairman DeviceNet UK, International Manufacturing Centre, University of Warwick, Coventry CV4 7AL. Tel: +44 (0)1203 524711; Fax: +44 (0)1203 524307; E-mail: r.mclaughlin@warwick.ac.uk