10
DEVICE EXPLANATION
10.6 Index Register(Z) / Standard Device Resister(Z)
10.6.3 Switching between scan execution and low speed execution types
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10.6.3 Switching between scan execution and low speed execution types
The CPU module saves (protects) and restores the index register (Z0 to 15) contents
when switching between a scan execution type program and a low speed execution type
program.
(1) When switching from a scan execution type program to a low speed
execution type program occurs.
The CPU module saves the index register value of the scan execution type program
and restores the index register value of the low speed execution type program.
(2) When switching from a low speed execution program to a scan
execution type program occurs.
The CPU module saves the index register value of the low speed execution type
program and restores the index register value of the scan execution type program.
(3) Exchanges of index register data
Note18
Word devices should be used for exchanges of index register data between scan
execution type programs and low speed execution type programs.
Figure 10.60 Saving and restoration of index register value at switching between scan and low speed execution type programs
Note18
Redundant
Basic
Note10.17
UD
Universal
Execution program
Index register value
Index
register
storage
area
For scan execution
type programs
For low speed
execution type
program
Scan execution
type program
Low speed
execution type
program
Saved
Reset
Saved
Reset
Saved
Reset
Z0=3
Z0=6
Z0=3
Z0=6
Z0=3
Z0=1
Z0=3
Z0=1
Z0=3
Z0=1
Z0=0
Z0=1
Z0=0
Z0=0
Z0=0
Switching
Scan execution
type program
Low speed
execution type
program
1: For low-speed execution type program, Z0 is changed to 3.
2: For scan execution type program, Z0 is changed to 6.
Z0=1
Z0=0 to Z0=3
1
Switching
Z0=1 to Z0=6
2
Switching
The Basic model QCPU, Redundant CPU and Universal model QCPU cannot use low speed
execution type programs. When the Basic model QCPU, Redundant CPU or Universal model
QCPU is used, it is not necessary to be conscious of the description in this section.
Basic
Redundant
UD
Universal
Содержание Q00CPU
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