Omron SYSMAC CS Series User Manual

127
Description of Operation Section 3-2
The operation cycle of specific function blocks can be specified to be shorter
than the default 1-second operation cycle in the following instances:
• To increase the response time of analog input/output and the PID opera-
tion execution cycle in a pressure or flowrate control loop
In this case, set the operation cycle of all function blocks that are used in
a single loop (for example, analog input, square root and other operations,
PID control and analog output) to the same shorter value.
• To increase the execution timing, for example, in Remote/Local switching
• To reduce the minimum resolution (time accuracy) of Timer and Counter
blocks on the Loop Controller
• The minimum resolution (time accuracy) of Timer and Counter blocks on
the Loop Controller is the same as the operation cycle. So, in this case,
set the operation timer of the Timer block (Block Model 205) and Counter
block (Block Model 208) to shorter values.
3-2-15 Conditions for Determining the Operation Cycle
The following conditions must be satisfied on the Loop Controller when deter-
mining the operation cycle:
1,2,3... 1. The LCB load rate (ratio between actual operation execution time and set
operation execution time) must be 80% or less. (For details, see 3-2-17
About the LCB Load Rate on page 130.)
2. The external I/O response time of the entire system must be appropriate
for the application.
The external I/O response time of the entire system relies on the CPU
Unit's cycle time and function block operation cycle. (Refer to 3-2-19 Exter-
nal I/O Response Cycle on the Overall System on page 132 for details.)
3. For Process-control CPU unit (CS1D-CPU@@P) only, the operation cycle
must be a minimum of 5 times the CPU Unit cycle time.
Function block G
Example: Basic PID
Loop Controller
Function block B
Example: Alarm
Function block A
Example: Link table
read
Function block C
Example: Step
Ladder Program
System common
operation cycle
Example: 1 s
Specific operation
cycle
Example: 100 ms
n
System common operation cycle
n
Specific operation cycle of only a certain
function block
Function block D
Example: Link table
write
Function block E
Example: Link table
read
Function block F
Example: Square
Root
Example: Link table
write
Function block H

Omron SYSMAC CS Series Specifications

General

Brand	Omron
Model	SYSMAC CS Series
Category	Controller
Language	English