Mitsubishi Q00JCPU User Manual page 682

10
DEVICE EXPLANATION
10
- 67 10.6 Index Register(Z) / Standard Device Resister(Z)
10.6.4 Switching scan/low speed exec. to Interrupt/fixed scan exec.
(b) When "High-speed execution" is selected
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 program
execution type
program
Index register value
Index register storage
area
For scan/low speed
execution type program
Figure 10.63 Index register saving (protection)/restoration (When "High-speed execution" is selected)
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
Figure 10.64 When data is written to index register by interrupt/fixed scan execution type program
Interrupt
Switching
program/Fixed
scan execution
type program
Transferred
Z0=1 Z0=1 to Z0=3
Z0=0 Z0=1
ZPUSH
ZPOP
IRET
Scan/low speed
Reset
execution type
program
Transferred
Z0=0 Z0=0
: For interrupt program, Z0 is changed to 3.
The points after D0 stores
D0
the data (Z0 to 15).
The data after D0 is stored
D0
in points (Z0 to 15).
Z0=3
Z0=0