Instruction times
6.1
General information
Calculation Principles
Application
Program
Execution Time
The execution time of the program can be calculated using the tables on the following pages to find the sum of all program instruction times.
Note: The time calculated is the maximum time. Operate blocks and subroutines are only processed if the condition of execution (logical equation determining the execution of a block or subroutine) is true, therefore it is possible that the actual time will be much shorter than the maximum time calculated.
Calculating the complete cycle time incorporates parameters which are specific to the PLC (overhead time, I/O Exchange time etc.). For the complete calculation procedure refer to the appropriate PLC operation manual (chapter on performance).
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Application
Memory Size
Instruction times
The size of the application is equal to the sum of the following elements:
Element
Program
Advanced functions
Configured PL7 objects
Configured input/output module
Comments
Calculation method
Calculate the sum of each program instruction, and multiply by the appropriate coefficient corresponding to the language in use
(see next page)
See
Memory Size for Advanced Functions, p. 230
See
Object memory size, p. 219
See
Review of the Memory Usage of Modules on Micro, p. 220
and
Memory Usage for Modules on Premium, p. 223
The program comments occupy 1 byte per character.
In the tables on the following pages, the information on sizes refers to the instruction code size.
To find out the total size of an instruction or a program, use a multiplication coefficient that takes into account information typical of each language.
Language
Ladder Language
Structured Text
Instruction List
Grafcet
Size
Total size = 1.7 x Code size
Total size = 1.6 x Code size
For the Micro PLC: Total size = 1.4 x Code size
For the Premium PLC: Total size = 1.6 x Code size
Chart size (in words) = 214 = 17 * number of chart steps = 2 * total number of configured steps + 4 * number of programmed actions
Note: The figures given in the following tables are average estimates, calculated using one application type. It is not possible to provide exact figures, as PL7 optimizes memory use according to the structure and contents of the application.
The chapter
Description of the memory zones, p. 218 gives a reminder of the
various memory areas taken up by the application.
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