Toshiba LC531 Series Instruction Manual page 207

G.2 Main Scan and Free Time
The LC53* executes main scan task applications as well as other system
processing. System processing includes transmission processing with the PLC
server, inter-controller transmission among LC53*, and EC bus transmission,
etc. To execute system processing without delay, free time in which no main
scan task is being executed is required. This time can be viewed as free time
from the Engineering Tool.
To make sure that the application functions normally in the LC53*, set the
main scan cycle time so that free time is 30% or more (at least 30ms), or
create the application taking into account the execution time of main scan
tasks.
For reference, the calculation formula for obtaining execution time per loop
is shown below.
Execution time of one loop =
PV tag processing time (0.35ms) + LP tag processing time (1.50ms) +
PID instruction word execution time (0.786ms) + Execution time of
other applications
CAUTION
Main scan cycle (100%)
Main scan task
Free time
30% or more > 30ms
When the main scan cycle time is short, sufficient
free time may not be reserved.
In this case, design the application by reducing the number of loops or
reducing other applications.
Unified Controller nv Series Single-Loop Controller LC531/LC532 Instruction Manual
G.2 Main Scan and Free Time
Main scan task
G
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