New-Tech Europe Magazine | July 2019 | Digital Edition

Making Inroads into High Speed Vision

Jenson Chang, LUCID Vision Labs

Since its introduction in 1980 and standardization in 1983 as IEEE 802.3, Ethernet allows computers to connect to other computers, servers, printers, scanners and other peripherals over single networks. These often use numerous switches that connect computers, printers and other wired devices to each other and are often wired to routers and models to allow Internet access. In office settings, especially, Ethernet is now the most popular and widely used network technology in the world with millions of computers and peripherals linked together with the standard. Like every other networking and interface standard, Ethernet has evolved from supporting data rates over ranging from the now obsolete 10BASE5 (10 Mbits/s), through 1000BASE-T (1 Gbits/s), and 10GBASE-T (10 Gbits/s). Newly introduced data rates over twisted

pair now include 25GBASE-T (25 Gbits/s) and 40GBASE-T (40 Gbits/s), part of the IEEE 802.3bq standard. In 2016, recognizing the need to develop a lower power, more cost- effective version of 10GBASE-T (10 Gbits/s) over twisted pair networks, the IEEE standards board ratified the 802.3bz standard which encompass 2.5GBASE-T and 5GBASE-T. A Balancing Act While 2.5GBASE-T specifies speeds of up to 2.5 Gbits/s and operating at distances to 100m over CAT 5e cable, the 5GBASE-T can operate as fast as 5Gbit/s at distances of 100m over CAT 6 cable. Although 10GBASE-T operates at 10Gbits/s and can be used for camera to computer distances of 55m (using CAT 6 cable) and 100m (using CAT 6A cable), Power over 10GBASE-T is not currently supported although it has been proven to work theoretically. In

addition, 2.5GBASE-T and 5GBASE-T allow system designers to forgo costly re-cabling of existing Ethernet solutions since the vast majority of installed Ethernet cabling is already CAT 5e and CAT 6 . Thus, the use of existing cabling combined with the lower power consumption and Power over Ethernet (PoE) has made 2.5GBASE-T and especially 5GBASE-T an attractive alternative, striking the right balance between speed, distance and costs not just for communication systems, but also for manufacturers of machine vision peripherals such as CMOS-based cameras. When compared with the fastest Camera Link Extended Full or Deca version that runs at a maximum of 6.8 Gbit/s over a maximum distance of 5m the benefits of a 5GBASE-T interface not requiring an expensive PC-based frame grabber or custom cabling also becomes apparent.

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