Implementation of a wireless data transmission path

October 01, 2014 // By Steven Weyrich, Arrow
In an intelligent factory equipped according to Industry 4.0, a central controller monitors and controls all areas, not only manufacturing.

Through wide-area use of smart sensors and actuators, manufacturing processes may be optimised and aspects such as security (access control, safety at work), energy efficiency (lighting and temperature control) and even connection to the smart grid may be controlled. Various wireless standards, optimised for certain applications, are available for the different tasks. To simplify data exchange between wireless networks and the central controller, Internet protocol based protocols find applications in the wireless world.

Progressive miniaturisation has produced very tiny sensors. They may be deployed, among other scenarios, for monitoring and controlling machines with much enhanced accuracy. One example of this would be using Hall sensors (e.g. the TLE499x line of Infineon) for constant monitoring of all moving machine tool shafts. These may be used to monitor speed and play of the shaft. The power consumption may also be calculated based on the revolutions. Smart grid linking can help to reduce the power consumption by adapting speeds as necessary, even for individual process steps. By measuring shaft play, wear may be diagnosed earlier and equipment servicing scheduled to suit production.

Automatic temperature monitoring in the food industry is another potential application. An infrared thermometer may be fitted at the cutting table to document the integrity of the cooling chain.

Both examples demonstrate new possibilities for collecting information using small sensors, allowing more accurate control and monitoring. For data transmission between sensor network and controller, data must be translated to the relevant protocols when the transmission system changes. The gateway links the two systems. Since data must be transmitted bidirectionally, the translation turns out somewhat more complicated. Equipment available on the market is therefore generally expensive and not intuitive to use.

A gateway for data exchange between the server in the manufacturing facility and the sensor must therefore be able to integrate data into the relevant protocols bidirectionally. The wireless transmission standards are all based on the IEEE 802.15.4 protocol. Data transmission via the Internet is based on conventional Internet protocols. When the Internet was born, addresses were defined using 32 bits. Available addresses have in the meantime run out, however, since the number of Internet capable devices has increased enormously. To solve this problem, Internet protocol Version 6 (IPv6) uses a 128 bit address. This suffices to (proverbially) “allocate an IP address to each grain of sand”.