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5 ACCESS FUNCTION USING NETWORK MODULE
5.5 Processing Time
Refresh cycle
The following shows how to calculate the refresh cycle.
For the setting method of refresh cycle, refer to the following section.
Page 49 Fixed Cycle Processing Function
How to decide the refresh cycle
Follow the procedure below to decide the refresh cycle.
1.
Calculation of the total link refresh time
2.
Preliminary decision of the refresh cycle
3.
Pre-operation of the C Controller system
4.
Decision of the refresh cycle
■
Calculation of the total link refresh time
The total link refresh time is equal to the sum of the link refresh time of all of the network modules controlled by a C Controller
module. The total link refresh time of a C Controller system in operation can be checked with the special registers (SD526 to
SD531).
For calculation method of link refresh time for each network module, refer to the following section.
■
Preliminary decision of the refresh cycle
Set the value which satisfies the following relational expression to the refresh cycle and total link refresh time.
• Refresh cycle > Total link refresh time
Pay attention to the processing of a user program so that the refresh cycle meets the system specifications of
the C Controller system.
■
Pre-operation of the C Controller system
Confirm whether the C Controller system operates correctly by the refresh cycle decided preliminarily.
Check the following at the time of pre-operation.
• Take the corrective actions shown below in order for the system to operate correctly when the C Controller system operates
abnormally or the processing performance of the user program is lowered.
Check item
Description
Any error has been occurred on the C
Controller module or not.
If the processing of the C Controller module has not been completed within the refresh cycle, an error, "Refresh cycle
exceeded (1846H)" occurs.
The operation of the C Controller
system meets the system
specifications or not.
Check that the C Controller system operates correctly. If the operation of the user program is suspended more
frequently than its normal operation time, the system specification may not be met.
Corrective action
Description
Increase the refresh cycle setting
value.
Set the refresh cycle again so that the following relational expression is met, by using the link refresh time (maximum
value) as an indication.
• Measured value of link refresh time (maximum value) < Refresh cycle
Reduce the setting number of refresh
points.
Review the number of refresh points in refresh parameter settings.
Review the user program.
Review the processing contents and task structure, and correct them to meet the system specifications and the
processing performance.
Summary of Contents for MELSEC iQ-R C R12CCPU-V
Page 1: ...MELSEC iQ R C Controller Module User s Manual Application R12CCPU V ...
Page 2: ......
Page 23: ...1 EXECUTING PROGRAMS 1 3 I O Access Timing 21 1 MEMO ...
Page 32: ...30 3 MEMORY CONFIGURATION OF C Controller Module 3 4 Files MEMO ...
Page 257: ...I 255 MEMO ...
Page 261: ......