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CS/CJ/NSJ Series Instructions Reference Manual (W474)
4. Instruction Execution Times and Number of Steps
4-1-37 Function Block Instance Execution Time
Use the following equation to calculate the effect of instance execution on the
cycle time when function block definitions have been created and the
instances copied into the user program.
The following table shows the length of time for A, B, and C.
Example: CJ2H-CPU67H-EIP
Input variables with a 1-word data type (INT): 3
Output variables with a 1-word data type (INT): 2
Total instruction processing time in function block definition section: 10 µs
Execution time for 1 instance = 3.3 µs + (3 + 2) × 0.19 µs + 10 µs = 14.25 µs
Note The execution time is increased according to the number of multiple
instances when the same function block definition has been copied
to multiple locations.
Note Number of Function Block Program Steps
Use the following equation to calculate the number of program steps when
function block definitions have been created and the instances copied into the
user program.
Note The number of instruction steps in the function block definition (p) will
not be diminished in subsequence instances when the same function
block definition is copied to multiple locations (i.e., for multiple in-
stances). Therefore, in the above equation, the number of instances
is not multiplied by the number of instruction steps in the function
block definition (p).
Effect of Instance Execution on Cycle Time
= Startup time (A)
+ I/O parameter transfer processing time (B)
+ Execution time of instructions in function block definition (C)
Operation CPU Unit model
CJ2H-
CPU6@H-EIP
CJ2M
CPU@@
A Startup time Startup time not including
I/O parameter transfer
3.3 µs7.4 µs
B I/O parameter trans-
fer processing time
The data type is indi-
cated in parentheses.
1-bit (BOOL) input sym-
bol or output symbol
0.24 µs 0.88 µs
1-word (INT, UINT,
WORD) input symbol or
output symbol
0.19 µs 0.88 µs
2-word (DINT, UDINT,
DWORD, REAL) input
symbol or output symbol
0.19 µs1.2 µs
4-word (LINT, ULINT,
LWORD, LREAL) input
symbol or output symbol
0.38 µs 2.96 µs
I/O symbols 0.114 µs0.4 µs
C Function block defini-
tion instruction exe-
cution time
Total instruction processing time (same as standard user
program)
Number of steps
= Number of instances × (Call part size m + I/O parameter transfer part size n × Num-
ber of parameters) + Number of instruction steps in the function block definition p
(See note.)
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