Profibus Ireland, which has grown its membership to about a dozen companies in a short space of time, will show a speed control system at the ISA Ireland exhibition.

Profibus Ireland will be having its first public outing since its foundation six months ago at the ISA Ireland exhibition in Cork on 26th April 2005. Profibus Ireland has grown its membership to about a dozen companies in a short space of time, which includes the big names such as ABB, Endress+Huaser, Irish Distillers, and Mitsubishi Electric. At the ISA exhibition Profibus Ireland will be provide live demonstrations of both Profibus and profinet displays, plus the latest in Profibus diagnostics tools.

It will show case a speed control system consisting of a PLC, a VSD, and a three-phase motor coupled to a generator.

The latter will provide the load changes to the motor.

The function of the control system is to provide a constant speed as the load changes.

The speed feedback is provided using a circular fin coupled to the motor axis, and a proximity sensor, which provides 12 pulses for every revolution.

The pulses from the sensor are counted using a high-speed counter on a distributed I/O module on Profinet, and the values are read through the Profinet by the Profinet I/O controller, and the necessary calculations are done using a PID algorithm.

The resulting controller output is gated through to the profibus network on which the VSD is a slave station.

This set-up will show not only a distributed control but also a distributed application where the application input (feedback) is provided from one network and the output is generated to another network.

Additionally the SCADA system for this application is provided using a web-server on the PLC.

The SCADA system can be accessed using Intranet or Internet to change set point, plot the speed-time graph as well as access to the historical data.