Mogens Mathiesen

Timing and power issues in wireless sensor networks - an industrial test case

This paper reports on experimental results of a wireless sensor network set up in an industrial automation facility at a Swedish mining company. It illustrates that the new ZigBee standard performs well even in heavy industrial environments. The main focus is on timing issues and achieving synchronized duty cycling. A simple synchronization algorithm is devised and shown to be sufficient to meet strict power consumption requirements.

WIRELESS AD-HOC NETWORKS FOR INDUSTRIAL AUTOMATION: CURRENT TRENDS AND FUTURE PROSPECTS

Abstract This paper provides an overview of recent advances in wireless communication technologies applied to industrial automation. Newly introduced communication concepts such as ad-hoc networks and wireless sensor/actuator networks now enable the deployment of extremely decentralised control architectures. Both open-loop and closed-loop applications are part of the roadmap, although data gathering and monitoring applications are expected to spread first. In addition to increased flexibility and facilitated operations, these new communication technologies have significant cost saving potential. Standardisation efforts led by international bodies such as the IEEE should propel prototyping and deployment activities in various industries.

Trial Implementation of a Wireless Human Machine Interface to Field Devices

In order to configure field instruments today, it is necessary for the operator to approach each device and program it using the human-machine interface (HMI) placed on the instrument. This paper describes a demonstrator concept of how to use wireless communication and a portable device to achieve this at a distance, and simultaneously with several instruments. The major problem that has to be overcome in order to use wireless communication is the severely limited power available. The instrument in question is running on a 4-20mA current loop, and the power for the wireless communication comes from the available internal current in the instrument, in this case limited to 400muA at 3.0V. Since the available power is constrained, the radio is duty cycled so that it mostly sleeps, and transmits only when there is power available.