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CHAPTER 4 DEVICES
4
4.6 Index Register (Z)/Standard Device Resister (Z)
4.6.3 Switching from the scan execution type to the interrupt/fixed scan execution type program
(b) When "High-speed execution" is selected
• When switching from the scan execution type program to the interrupt/fixed scan execution type program
The CPU module does not save/restore any index register values.
• When switching from the interrupt/fixed scan execution type program to the scan execution type program
If data are written to the index register by the interrupt/fixed scan execution type program, the values of the
index register used in the scan execution type program will be corrupted.
*1 The Z0 value is changed to 3 in the interrupt program.
When writing data to the index register by the interrupt/fixed scan execution type program, use the ZPUSH or
ZPOP instruction to save and restore the data.
(3) Processing of file register's block numbers
• When switching from the scan execution type program to the interrupt/fixed scan execution type program
The CPU module saves the file register block numbers in the scan execution type program, and passes
them to the interrupt/fixed scan execution type program.
• When switching from the interrupt/fixed scan execution type program to the scan execution type program
The CPU module restores the saved block numbers of the file register.
Execution program
Z0=1
Z0=0
Switching
Restored
Passed Passed
Z0=0 Z0=0 Z0=0 Z0=0
Z0=3
Index register value
Save area of index register
for scan execution
type program
Scan execution
type program
Interrupt/fixed scan
execution type
program
Scan execution
type program
Z0=1 Z0=3
*1
ZPUSH D0
SM400
ZPOP D0
SM400
IRET
I0
Data in Z0 to Z15 are
stored in the area
addressed from D0.
Data in the area
addressed from D0 are
stored in Z0 to Z15.
[RSET K0]
Execution program
Save area
Switching
Restored
Block 1
Restored
Block 1Block 1Block 1 Block 1Block 0
Block 1
Passed
Saved
Block1 0
Block No. of
file register
Scan execution
type program
Scan execution
type program
Interrupt/fixed scan
execution type
program
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