New Standards For Connectivity

Power line, Bluetooth and EtherCat take important steps to move forward; focus is on speed and lower power.

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By Pallab Chatterjee
The last couple of months have been busy for data transfer standards.

Consider the following moves:

  1. Power Line Communication (PLC) has become a new standard by the IEEE and has two groups promoting it: HD-PLC and Home Plug Alliance.
  2. Bluetooth also has made progress with the draft of the new Bluetooth Low Energy Technology as part of the July version 4 specification.
  3. EtherCAT technology group recently announced its advanced control architecture for factory networking.

The Power Line Communications group has been adopted by the IEEE as the 1901 networking standard. The networking data is segmented into two groups – AV and GP. The HomePlug AV group has a targeted data rate of 200Mbps over the power line in a single facility. This data rate and power is designed to accommodate streaming media, remote and on-line gaming and whole house audio connectivity. This network is compatible with having devices on a traditional wired or WiFi network. Several products are currently on the market, such as those from Atheros and incorporated in the Monster Cable PowerNet and Netgear products.

Supplementing the AV version, there is a GP version, which stands for Green Phy. This specification is targeted at Smart-Grid applications and is for modules operating appliances, lighting, and other similar uses. The GP spec has significantly reduced power requirements (75% reduction), a significantly reduced cost and a data rate of 1Mbps (3.8Mbps Peak for the PHY). Further information on the Smart Grid application can be found in the joint working group document created by the Home Plug Alliance and the Zigbee Alliance.

Meanwhile, the Bluetooth group has finally released its Low Energy Technology specification. The specification already was adopted as a supplemental protocol by the Continua Health Alliance. The features of the new specification include ultra-low peak, average and idle mode power consumption; the ability to run for years on standard coin-cell batteries; low cost; multi-vendor interoperability and enhanced range.

The standard Bluetooth high-speed technology is for the transfer of video, music and photos between phones, cameras, camcorders, PCs and TVs and is for rechargeable battery operation. Bluetooth low-energy technology is for low-power sensor devices and accessing new Web services within the health care, fitness, security, home entertainment, automotive and automation industries. The entire space of the Bluetooth interface has matured to the point where there are more than eight new Bluetooth enabled products being qualified every working day and more than 19 million units shipping per week. So far there are nearly 3 billion Bluetooth devices in the marketplace,

In addressing the industrial space, such as for wafer fabrication, LCD display fabrication, and assembly line robotics, the EtherCAT specification was recently adopted and the Advanced Control Architecture has been released. The interface is a factory automation interface for both machine control and data communication using Ethernet and stand CAT5/CAT6 cables. The protocol conforms for the standard 802.3 specification using a header string following the Ethernet header (see Fig. 1)

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The specification operates at over 100Mbps and supports cable lengths up 100 meters each with up to 65,535 devices in a single chain. The advantages of the EtherCAT protocol include being full duplex at the 100Mbps data rate, and having cycle times of 50 to 250µs versus traditional field-bus systems, which typically have 5-15ms update cycles. The high data rate also allows for the increase in data collection rates from 10 to 100Hz for standard SEMI field tools, up to 20KHz concurrent with the control data traffic. This allows for both feed forward and feedback control loop designs that can incorporate dynamic adjustments from in-process data collection.

Additional information on the specification and applications from the over 1300 member companies can be found here.