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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
37 Operation of Special Devices (M8000 -, D8000 -)
37.1 Special Device List (M8000 -, D8000 -)
37. Operation of Special Devices (M8000 -, D8000 -)
37.1 Special Device List (M8000 -, D8000 -)
The device numbers and functions of the special auxiliary relays (indicated as "special M" in tables) and special data
registers (indicated as "special D" in tables) are shown below.
Note that functions of certain devices vary depending on the series of the PLC.
Do not use the undefined / blank special auxiliary relays and special data registers in the sequence program since
they are occupied by the CPU.
In addition, do not activate or write to the devices with brackets on the first letter such as [M]8000 or [D]8001 in the
program.
→ Refer to Section 37.2 for supplementary information on analog special adapter devices.
37.1.1 Special Auxiliary Relay (M8000 to M8511)
Number and name Operation and function
Applicable model
FX
3G FX3U
FX
3UC
Correspond-
ing special
device
FX
1S
FX
1N
FX
2N
FX
1NC
FX
2NC
PLC Status
[M]8000
RUN monitor
NO contact
→Refer to Subsection 37.2.1.
3 3 3 – 33333
[M]8001
RUN monitor
NC contact
3 3 3 – 33333
[M]8002
Initial pulse
NO contact
3 3 3 – 33333
[M]8003
Initial pulse
NC contact
3 3 3 – 33333
[M]8004
Error occurrence
•FX
3G, FX3U, FX3UC
ON when either M8060, M8061, M8064, M8065,
M8066, or M8067 is ON.
•FX
1S,FX1N,FX2N,FX1NC,FX2NC
ON when either M8060, M8061, M8063, M8064,
M8065, M8066, or M8067 is ON.
3 3 3 D8004 3333 3
[M]8005
Battery voltage low
ON when battery voltage is below the value set in
D8006.
→Refer to Subsection 37.2.3.
3 3 3 D8005 – – 3 – 3
[M]8006
Battery error latch
It is set when battery voltage low is detected.
→Refer to Subsection 37.2.3.
3 3 3 D8006 – – 3 – 3
[M]8007
Momentary power
failure
ON for 1 scan, when momentary power failure is
detected
Even if M8007 turns ON, PLC continues to RUN as long
as the duration of power loss is within the time period
specified in D8008.
→Refer to Subsection 37.2.4.
– 3 3
D8007
D8008
––3 – 3
[M]8008
Power failure
detected
Set when momentary power failure is detected.
If power loss time is longer than the time period
specified in D8008, M8008 is reset and PLC is switched
to STOP mode.(M8000=OFF).
→Refer to Subsection 37.2.4.
– 3 3 D8008 – – 3 – 3
[M]8009
24V DC down
ON when 24V DC power fails in either powered
extension unit or extension power supply unit.
3 3 3 D8009 – – 3 – 3
1 scan time
RUN
input
M8000
M8001
M8002
M8003
M8061
Error occurrence