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12.7 Special Register List
12
TROUBLESHOOTING
12.7 Special Register List
The special registers, SD, are internal registers with fixed applications in the programmable
controller.
For this reason, it is not possible to use these registers in sequence programs in the same
way that normal registers are used.
However, data can be written as needed in order to control the CPU modules and remote I/
O modules.
Data stored in the special registers are stored as BIN values if no special designation has
been made to the contrary.
The heading descriptions in the following special register lists are shown in Table12.20.
For details on the following items, refer to the following manuals:
• Networks Manuals of each network module)
POINT
In the program that achieves the safety function, only SD1000 to SD1299 can be
used.
Special register other than SD1000 to SD1299 cannot be used in the program that
achieves the safety function.
Table12.20 Descriptions of the special register list headings
Item Function of Item
Number • Indicates special register number
Name • Indicates name of special register
Meaning • Indicates contents of special register
Explanation • Discusses contents of special register in more detail
Set by
(When set)
• Indicates whether the relay is set by the system or user, and, if it is set by the system, when setting is performed.
<Set by>
S : Set by system
U : Set by user (sequence programs or test operations from GX Developer)
S/U : Set by both system and user
<When set>
Indicated only for registers set by system
Every END : Set during every END processing
Initial : Set only during initial processing (when power supply is turned ON, or when going from STOP to RUN)
Status change : Set only when there is a change in status
Error : Set when error occurs
Instruction execution : Set when instruction is executed
Request : Set only when there is a user request (through SM, etc.)
Writing to ROM : Set when writing to ROM