Special Relays, Special Registers - Mitsubishi Electric 700 Series Programming Manual

3.12 Special Relays, Special Registers

Special relays and special registers are internal relays and data registers, respectively,
whose applications are predetermined by the built-in PLC functions.
They have the following main applications.
(1) Sequence operation check
The special relays and special registers can be used to:
(a)Check the operating status (RUN/STOP)
(b)Detect a fault by the self-diagnostic function
(c)Detect an operation error
(d)Check the scan time
(2) Timing contact
There are special relays that can be used in a sequence program and differ in
operating status.
(a)Normally ON/OFF flag
(b)RUN flag (OFF for 1 scan)
(c)Initial processing flag (ON for 1 scan)
REMARKS
For the special relays and special registers usable with the built-in PLC function,
refer to page 10 .
Special Relays, Special Registers
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