Local communication networks for industrial automation
- 1 January 1989
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in Canadian Journal of Electrical and Computer Engineering
- Vol. 14 (4) , 138-146
- https://doi.org/10.1109/cjece.1989.6592913
Abstract
The author presents a study of the physical and data link layers of the dynamic token-passing bus protocol. This protocol is a variant of the IEEE 802.4 token-passing bus protocol and can therefore be applied to communication systems which support industrial automation. Simulation results have been used for operational validation and extensive evaluation of the communication network's performance. The complex process of allocating a portion of the channel bandwidth to scheduling control, in a completely distributed fashion, has been investigated. The protocol is capable of efficient operation for the full range of channel utilization, while its dual-phase behaviour provides for a reliable and flexible channel assignment scheme. Thresholds have been determined for switching between the modes, and a hardware unit has been proposed which monitors the bus activities and, using existing signals, generates the switch-over command. Two recommendation for modifications of the existing 802.4 standard are also proposed which increase the reliability and reduce the overheads of the logical ring maintenance functions.Keywords
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