Industrial Ethernet video: Protocol requirements, application
Industrial-grade Ethernet based video applications can be set up for real time viewing or be stored for later review, according to Peter Wood, GarrettCom vice president of engineering. He says some applications provide information about what is happening as recorded by on-site video cameras and sent to consoles for review– either to alert someone when a problem develops (and possibly provide for remote control of the situation to effect a change – such as the Vermont Department of Transportation (VDOT) application of Ethernet video or some factory process monitoring ) or to store and review later (perhaps for process improvement).
What’s needed in the protocol: Typical Ethernet protocols are UDP (the classical Ethernet protocol for moving packets within an Ethernet network) and TCP/IP, which adds additional information to support IP stack (and further upstream) requirements. Because streaming video is a high-bandwidth application, limiting additional processing overhead is ideal in any way possible. UDP has less overhead than TCP/IP for local network transmissions (managed by an Ethernet switch). When a router is necessary for passing data beyond the local network, TCP/IP is the preferred choice.
To reduce bandwidth requirements when all video camera (or stored video) is not required at all video viewing sites, Internet Group Management Protocol (IGMP) and GarrettCom’s switch-level subset, IGMP-L2 can provide multicast support rather than bandwidth-wasting unicasting.
GarrettCom offers a short technical brief about multicasting support
Some applications may be supported by a switch-based network (star, ring, mesh or daisy-chain) while others may require a router.
As for the V-DOT application, it is simply an implementation opportunistic implementation of video over Ethernet Wood says; since the Ethernet capability was there, adding video provided major traffic performance incentives. In a manufacturing facility, he adds, the same opportunity to visually monitor some activities and take remote action when the situation warrants, can provide cost savings and increased efficiency.
—Edited by Mark T. Hoske , editor in chief
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