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CONFIGURATION
FUNCTION BLOCKS
I-E96-213A
4 - 3
d. Add products:
23,780
9,020
+ 512
33,312 bytes of RAM
There are 97,776 bytes available at the beginning. There are
64,464 bytes of RAM remaining.
6. Calculate the amount of CPU time the configuration
requires to run. First, calculate the maximum amount of CPU
time. Next, calculate how much CPU time the low priority loops
require.
a. Multiply 100 PID blocks by 690 microseconds = 0.069
seconds
b. Multiply 100 Square Root blocks by 240 microseconds
= 0.024 seconds
c.
Add products:
0.069
+ 0.024
0.093 seconds of CPU time
The result of this calculation gives the user the amount of CPU
time that the low priority control functions use during execu-
tion every 2 seconds.
7. Calculate the amount of CPU time used by normal priority
loops of control functions.
a. Determine the number of times the normal priority
loops run during the amount of CPU time specified. In this
example, multiply 4 times/second by 2 seconds. The nor-
mal priority function blocks will be executed 8 times.
b. Calculate the amount of CPU time that will be used
each time
the normal priority function blocks are exe-
cuted.
100 PID blocks x 690 microseconds
=
0.069 seconds
100 Square Root blocks x 240 microseconds = +0.024 seconds
Total =
0.093 seconds