Tuesday, September 27, 2011

Execution Time of Mnemonics Ladder Diagram PLC





Execution time and translation time can be judged as key factors for evaluation of performance. First, the time of translation of the existing technique is a lot shorter than that of the method of proposed. To acquire executable code of binary with the method of proposed the program of LD application have to pass throughout several steps procedure for example converter of LD mnemonics macro assembler and compiler. Besides the input and output is in use at every step. But generally once a program application of PLC has been set with no modification of the program it is utilized for a long time around several years. Stopping operation of PLC for renew of the program application can cause a huge loss to the customers. Since the customers do not discover a difficulty in time because of infrequent translation, translation time is not associated to the PLC performance.

Consequently, it is accomplished that the part for the LD translator evaluation is not translation time but the application program execution time. They measured the LD mnemonics execution time. For both techniques the graph of mean value of calculated execution time of a variety of kind mnemonics of LD. The mnemonics are categorized based on their purpose and form according to the grouping of the manufacturers of PLC.

The common mnemonic of arithmetic usually has three operands which comprise of two resources and one target. The mnemonics with three operands reside in the majority of common mnemonics of PLC. They offer the biggest the execution times reduction because they exceed operand routine three times at minimum and get the middle code in memory extra regularly. On the mnemonics of contrary flow control are in the least decrease because mnemonics of flow control have brief machine code and have an operand as label. Hence, the structure of proposed is capable when mnemonics of LD have longer code and more operands.

The automatic control of LD program a shuttle process utilized in a manufacturing process of automotive. The sequence operation of the process is Home Position  Shuttle Up Shuttle Advance  Shuttle Down  Shuttle Return  Home Position  LD programming can be performed for a variety of purposes and is not unique. The operations of arithmetic for instance add, mul, and sin can be allocated as results in LD. They also can be characterized as a function block FB form. These operations of non logical are separated into common arithmetic sub, add, mul, etc. and special arithmetic such as sin, cos, PID etc.



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