Abstract
This paper examines the effect of scan time (S/T) of programmable logic controllers (PLCs) on cycle time (C/T). S/T is considered an internal feature of the PLC, and it becomes economically impracticable to examine different PLCs to vary scan time and to monitor the effect on cycle time. Although the relationship between the two parameters is expected to differ in linear proportion, an optimum S/T region exists beyond which the rate of C/T change decreases. This region of scan time is particularly important for practitioners because more investment in the processor's speed might not achieve convenient reduction in cycle times. The effect of scan time variation on discrete event processes has been investigated during this research, and factors influencing cycle time have been identified. Also, using intelligent decision analysis tools in engineering has been considered through associated work in which the analytic hierarchy process (AHP) and fuzzy logic have been employed in an intelligent system. In this paper, different criteria that affect the scanning time of a PLC are examined. The methods use a multiple-criteria decision-making tool, called AHP (analytic hierarchy process), that gives a prioritized rank of alternatives that contribute to those criteria.
Original language | English |
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Pages (from-to) | 95-109 |
Number of pages | 15 |
Journal | International Journal of Flexible Automation and Integrated Manufacturing |
Volume | 6 |
Issue number | 1 |
Publication status | Published - 1 Jan 1998 |