Mitsubishi Q00JCPU User Manual page 511

9
DEVICE EXPLANATION
(b) When "High-speed execution" is selected
Execution program
Index register value
Index register storage
area
For scan/low speed
execution type program
Diagram 9.62 Index register saving (protection)/restoration (When "High-speed execution" is selected)
Diagram 9.63 When data is written to index register by interrupt/fixed scan execution type program
1) When switching from scan/low speed execution type program to
interrupt/fixed scan execution type program
The CPU module does not save/restore the index register value.
2) When switching from interrupt/fixed scan execution type program to
scan/low speed execution type program
If data is written to index registers by using an interrupt program/fixed scan
execution type program, the values of index registers used for an scan/low
speed execution type program will be corrupted.
Scan/low speed
execution type
program
Z0=1
Z0=0
Before writing data to index registers by using an interrupt program/fixed scan
execution type program, use the ZPUSH/ZPOP instruction to save/restore the
data.
SM400
I0
SM400
9.6.2 Switching scan/low speed exec. to Interrupt/fixed scan exec.
Interrupt
Switching
program/Fixed
scan execution
type program
Transferred Transferred
Z0=1 to Z0=3
Z0=1 Z0=0
: For interrupt program, Z0 is changed to 3.
The points after D0 stores
ZPUSH D0
the data (Z0 to 15).
The data after D0 is stored
ZPOP D0
in points (Z0 to 15).
IRET
9.6 Index Register (Z)
Scan/low speed
Reset
execution type
program
Z0=3
Z0=0
Z0=0
9
- 60
9
10
11