Saving And Restoration Of The Index Register - Mitsubishi Electric L02SCPU User's Manual And Reference

5.6.3

Saving and restoration of the index register

The CPU module performs the following when switching from the scan execution type program to the interrupt/fixed
scan execution type program.
• Saving and restoring the index register data
• Saving and restoring block numbers of the file register
(1) Setting for saving and restoration
Configure the setting for saving and restoration using a programming tool.
Project window  [Parameter]  [PLC Parameter]  [PLC System]
Selecting this
saves or restores
index register data.
When not writing data to the index register during interrupt/fixed scan execution type program, select "High
Speed Execution" in the Interrupt Program/Fixed Scan Program Setting area. This setting enables faster program
switching because saving and restoration are not performed.
(2) Processing of the index register
(a) When "High speed execution" is not selected
1) The CPU module saves the index register
values and passes them at program
switching.
Execution program
Index register value
Index register save area
for scan execution
type program
*1 The Z0 value is changed to 3 in the interrupt program.
To pass index register values from the interrupt/fixed scan execution type program to the scan execution type program, use
word devices.
324
Scan execution
Switching
type program
Passed
Z0 = 1
Saved
Z0 = 1
Z0 = 0
2) The CPU module restores the index
register values saved at program switching.
Interrupt/fixed
Restored Scan execution
scan execution
type program
type program
1
*
Z0 = 1 Z0 = 3
Z0 = 1 Z0 = 1
Z0 = 1
Restored
Z0 = 1