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App. - 2
Appendix 1.2 Refresh mode
In the refresh mode, all changes caused in an input module are imported to the input
data memory in a programmable controller CPU before every scan. The data in the
data memory is used for an operation.
The operation results made in a program for output (Y) are stored to the output data
memory at every operation. All the data stored in the output data memory is
batch-output to the output module after the execution of the END instruction.
The following diagram shows the flow of I/O data in the refresh mode.
Data memory for
inputs (X)
Data memory for
outputs (Y)
Programmable controller
CPU
(Operation processing)
Output
module
Y70
X0
Y75
Input
module
1)
When inputs
are refreshed
When outputs
are refreshed
2)
3)
4)
5)
• Input refresh
Input data in the input module is batch-read 1) before the execution of the step 0,
and stored to the data memory for input (X).
• Output refresh
Data 2) in the data memory for output (Y) is batch-output to the output module
before the execution of the step 0.
• When the input contact instruction is executed:
The input data is read from the data memory for input (X) 3), and a sequence
program is executed.
• When the output contact instruction is executed:
The output data 4) is read from the data memory for output (Y), and a sequence
program is executed.
• When the output OUT instruction is executed:
The operation result of the sequence program 5) is stored in the data memory for
output (Y).