General Motors tests Ethernet on the factory floor

General Motors this week launched a pilot project to test the viability of using standard Ethernet network gear and Internet communications protocols in automotive manufacturing.

The test will use TCP/IP running over Ethernet to link eight programmable logic controllers that oversee machinery used in body shop tooling. The controllers previously used a special-purpose industrial network protocol from Rockwell International Corp.'s Automation division called ControlNet. GM migrated ControlNet to the emerging EtherNet/IP standard, which was developed by Rockwell and several industrial automation groups.

Gary Workman, a staff development engineer at GM's Technical Centre in Warren, Michigan, says the project's goal is to collapse the three networks employed by GM's manufacturing lines - Ethernet at the IT level, ControlNet at the controller level and DeviceNet at the device level - into two networks.

"We want to get rid of ControlNet and just support two protocols," Workman says. "This should be a little easier to configure, and we expect indirect cost savings in running two network protocols vs. three."

He says the cost savings will come from stocking spare parts and training staff for only two network protocols. He also says GM can use its Ethernet-based diagnostic and design tools instead of buying tools specifically for ControlNet.

If the project goes smoothly, Workman hopes to install EtherNet/IP on a production manufacturing line used to build the underbodies of vehicles.

"We hope that before the Christmas shutdown, we'll be able to reconfigure the networks on that line to get rid of ControlNet and just run EtherNet/IP for the first half of next year," Workman says. "Eventually, GM expects to be able to use EtherNet/IP quite extensively."

Open DeviceNet Vendor Association, a factory automation group with more than 300 corporate members, announced EtherNet/IP in March. The technology has the support of ControlNet International and the Industrial Ethernet Association.

EtherNet/IP lets manufacturing plants take advantage of inexpensive, commercial-grade Ethernet equipment to tie together industrial controllers and devices. It uses the application layer common to DeviceNet and ControlNet networks, and it encapsulates DeviceNet and ControlNet messages over Ethernet without gateways.

EtherNet/IP will be available free to product developers later this summer. The first EtherNet/IP-compliant products are due out this fall.

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