Wireless Networking Technology

Wireless communication has been around for some years for office and home applications. For use in industrial automation we are still in the early adoption stage and their are still major concerns with regards to security, safety and reliability issues within wireless communication.

Even if several technologies have been proved to meet industrial requirements, the industrial market is not yet ready to adopt wireless communications without the guarantees regarding these concerns.

Its important to look on the specific application before selection a wireless technology within Industrial automation. In general two classes of applications are common.

Wireless I/O
Remote access and diagnostics

Wireless I/O
In this market segment the wireless technology is used to get data from sensors and controlling actuators in its local area. The range can typically be 10-100 meters from a central control system. There are two major benefits:

No wires make it possible to communicate with moving applications such as a robot arm.

Lower cost to add a sensor, since no wiring and limited installation cost apply. This makes it possible for a control system to get data from more sensors in the process, thus enabling more accurate control.

An issue with both these applications are that even if the communication is wireless, the application needs power. Until today, no real low power communication technology is available. To meet industry requirements, a battery powered device must at least run three years before battery re-charge.

Since there are needs to connect devices from several different vendors to the same wireless network there is a large demand for an open and established standard. The two most promising technologies in the “Wireless I/O” area are:

Bluetooth
Bluetooth wireless technology is a short-range radio technology. Bluetooth wireless technology makes it possible to transmit signals over short distances between telephones, computers and other devices and thereby simplify communication and synchronization between devices.

Bluetooth wireless technology provides a universal bridge to a peripheral interface, and a mechanism to form small private ad hoc groupings of connected devices away from fixed network infrastructures.

Bluetooth radio uses a fast acknowledgement and frequency-hopping scheme to make the link robust, even in noisy radio environments.

Zigbee
ZigBee technology is based upon IEEE 802.15.4. It is capable of 65,536 network (client) nodes and it is optimized for applications within Building Automation, Industrial automaton as well as commercial applications. With unique low-power features it can be used for battery powered devices within industrial automation. It support Full Mesh Networking which allows an intelligent way of distribute data within a ZigBee network

Remote access and diagnostics
This market is mainly for remote locations and remote devices, located up to several kilometres away from the central control system. Even if there are commercially available standard solutions today, most applications are using some kind of proprietary technology & protocol, normally using any of the free frequency bands. Currently the market accepts proprietary solutions, as these are more difficult to “listen to” by unauthorized users (“hackers”) since it is using a proprietary protocol, but also this market will move to open standards when security and safety issues are solved.

Use of mobile phone networks, like 3G/UMTS, are used more and more, especially as the GPRS technology only charge the user on data transferred rather than connected time. However, firewalls and internal security polices are making it difficult to solve all applications with GPRS.

New technologies are coming up, like Wimax, which are expected to be very useful for Remote access and diagnostics.

See Wireless Anybus Products