Chapter 5 Program Configuration and Operation Method
5
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3
5.1.3 Scan Time
The time required to complete it from the first step 0 to the next step 0 of a program, that is, a time taken for a
control operation is called ‘scan time.’ It is directly related to the control performance of the system.
1) Operation and performance of XGK
Program execution time, I/O data process time and communication service time are important factors
affecting the ‘scan time.’
The XGK impressively reduces scan time by means of the improved data reception performance through
backplane, ladder program execution and ladder program execution by MPU and parallel execution of I/O
data scan etc.
Program processing time
Module processing time
Type
Ladder
execution
(32kstep)
System
Task
Digital I/O
module
(32 points,
1module)
Analog
module
(8 ch,
1module)
Communication
module
(basic/extension)
(200 byte, 1 block)
CPUH 0.896
ms 0.6
ms
CPUS 2.688
ms 0.8
ms
20 us
75 us
170 + 44(200byte 1 block)
㎲
2) Calculation of scan time
The CPU module executes controls along the following steps. A user can estimate the control performance
of a system that the user is to structure from the following calculation.
(1) Scan
time
=
①
Scan program process
＋
②
System check & Task process
＋
③
I/O data R
④
Network S
⑤
XG5000 S
⑥
User Task Program process
Scan program process = no. of program steps created x 0.028 (
①
㎲
) [0.084 for CPUS]
②
System check & Task process: 600
㎲
~ 1.0 ms [parameter depending on the usage of auxiliary
functions]
I/O data Refresh [including special module]: minimum 0.06ms~0.2ms
③
Program
Scan
①
Ladder Scan
Ladder Scan
BP Controller
Scan
Ladder Scan
I/O Module
Data Refresh
②
System check &
Task process
④
Network Service
③
I/O data Refresh
Network Module
Data exchange
Inpu
t
Outpu
t
⑤
XG5000 service
