APPENDICES
APP
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28
APPENDIX3 SPECIAL RELAYS AND SPECIAL REGISTERS
3.1
Special Relays (SP, M)
The special relays are internal relays with fixed applications in the programmable
controller. Accordingly, they must not be turned ON and OFF in sequence
programs (those marked (Note-1) and (Note-2) in the table are exceptions).
Table 3.1 Special Relay List
Number
Name
Stored Data
Explanation
M9000
(Note-
1)
Fuse blown
OFF Normal
ON
There is a module with a blown
fuse.
!
Comes ON even if there is only one output module with a blown fuse,
and remains ON even after return to normal.
M9002
(Note-
1)
I/O unit verify error
OFF Normal
ON
Error
!
Comes ON if there is a discrepancy between the actual I/O modules
and the registered information when the power is turned on.
M9005
(Note-
1)
AC DOWN detection
OFF AC DOWN detected
ON
AC DOWN not detected
!
Comes ON when there is a momentary power interruption not
exceeding 20 ms; reset by turning the power OFF then ON again.
M9006
Battery low
OFF Normal
ON
Low battery voltage
!
Comes ON when the battery voltage falls below the stipulated value;
goes OFF when normal battery voltage is re-established.
M9007
(Note-
1)
Battery low latch
OFF Normal
ON
Low battery voltage
!
Comes ON when the battery voltage falls below the stipulated value;
remains ON even after normal battery voltage is re-established.
M9008
(Note-
1)
Self-diagnostic error
OFF No error
ON
Error
!
Comes ON when an error occurs as a result of self-diagnosis.
M9009
Annunciator detection
OFF No F number detected
ON
F number detected
!
Comes ON when OUT F, SET F instructions are executed.
Goes OFF when 0 is stored in D9124.
M9010
Operation error flag
OFF No error
ON
Error
!
Comes on when an operation error occurs during execution of an
application instruction; goes OFF when the error is cleared.
M9011
(Note-
1)
Operation error flag
OFF No error
ON
Error
!
Comes on when an operation error occurs during execution of an
application instruction; remains ON even after the error is cleared.
M9012
Carry flag
OFF Carry OFF
ON
Carry ON
!
Carry flag used in an application instruction.
M9016
Data memory clear flag
OFF No processing
ON
Output cleared
!
When M9016 is ON, all data memory contents, including those in the
latch range but with the exception of special relays/registers, are
cleared on reception of remote RUN from a computer or other
device.
M9017
Data memory clear flag
OFF No processing
ON
Output cleared
!
When M9017 is ON, all data memory contents that are not latched,
with the exception of special relays/registers, are cleared on
reception of remote RUN from a computer or other device.
M9020
User timing clock No.0
M9021
User timing clock No.1
M9022
User timing clock No.2
M9023
User timing clock No.3
M9024
User timing clock No.4
n2
scan
n2
scan
n1
scan
!
Relay repeats ON/OFF switching at fixed scan intervals.
!
Starts from the OFF status when the power is turned ON or on resetting.
!
The ON/OFF intervals are set with the DUTY instruction.
DUTY
n1
n2
M9020
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