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5.3 The System Switching Function
5.3.4 Both Systems Operations After System Switching
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5.3.4 Both Systems Operations After System Switching
Table5.36 and Table5.37 indicates the CPU module and network module operations after
system switching is performed.
(1) CPU Module Operations
* 1: The redundant CPU cannot execute the low speed execution type programs.
Table5.36 Control System and Standby System CPU Module Operation After System Switching
Item
New Control System CPU Module
New Standby System CPU Module
Program
Execution
*1
Initial Execution
Type Program
Does not execute the program.
However, executes the initial execution type program from the
0 step again, if it was not completed in the previous control
system at the time of system switching.
Stops program execution.
Scan Execution
Type Program
Executes scan execution type program based on the tracked
device data from step 0.
Fixed Scan
Execution Type
Program
Starts counting the interrupt interval time from 0. (Refer to
Section 7.2)
Standby Type
Program
Not executed.
Interrupt
Program
Executes when the interrupt factor is established. (Refer to
Section 7.2)
Tracking
Starts tracking to the new standby system.
Starts reception of tracking data.
However, stops the reception of tracking data if a stop error
has occurred.
Online Program Change
Continues the write operation after system switching.
Continues the write operation after system switching.
Writing files in RUN
Continues the write operation after system switching.
Continues the write operation after system switching.
General Data Processing
Executes the request received after system switching.
Executes the request received at time of system switching.
However, may develope a communication error if a system
switching is executed during general data processing.
Device Memory
Holds the data.
Holds the data.
Sets the received tracking data to specified device.
Signal Flow Memory
Holds the tracked data.
Turns ON signal flow memory in all steps if has not been
tracked.
Stores the execution results in the signal flow memory, after
program execution.
Holds the data
Sets the received tracking data in the signal flow memory.
Initial Device Value Setting
Does not set the value.
Does not process it.
Special Relays and Special
Registers
Holds the data.
However, stores the statuses of control system and standby
system after system switching in SM1515 and SM1516.
Holds the data.
However, stores the statuses of control system and standby
system after system switching in SM1515 and SM1516.
Sets the received tracking data in the corresponding special
relay and special register.
Output (Y)
Holds the output.
Outputs program execution results.
Turns OFF the output (Y) from modules mounted on the
main base unit.
Holds the output (Y) from modules other than above.
Local Device Settings
Sets devices according to parameter settings.
Does not process it.
File Register Settings
Holds the file register settings prior to system switching.
Not processed.
Direct Input (DX)
Takes in (X) from the input module when executing the direct
input instruction in a program after system switching.
Not processed.
Direct Output (DY)
Outputs (Y) to the output module when executing the direct
output instruction in a program after switching.
Not processed.
Intelligent Function Module
Dedicated Instruction
Executes the instruction in a program after system switching if
the corresponding execution condition has been satisfied, and
does not execute it if it has not been satisfied.
Not processed.
FROM/TO Instruction
Executes the instruction in a program after system switching if
the corresponding execution condition has been satisfied, and
does not execute if it has not been satisfied.
Not processed.
Access Request from Intelligent
Function Module
Ignores the access request.
Not processed.
