Mitsubishi Electric FX Series - Special Registers; PLC Status Diagnostic Information (D8000 to D8009

A.2 Special Registers
Just like the special relays (section A.1) starting at address M8000 the FX controllers also have
special or diagnostic registers, whose addresses start at D8000. Often there is also a direct con
-
nection between the special relays and special registers. For example, special relay M8005
shows that the voltage of the PLC’s battery is too low, and the corresponding voltage value is
stored in special register D8005. The following tables shows a small selection of the available
special registers as examples.
Special registers can be divided in two groups:
–
Special registers whose value can only be read by the program
–
Special relays whose value can be read and written by the program.
The following tables feature a "Read" and a "Write" column. If the symbol "쎲" is shown in a one of
these columns, the corresponding action is possible. The symbol "—" means that the corre
-
sponding action is not allowed.
A.2.1 PLC Status Diagnostic Information (D8000 to D8009)
Special Registers Appendix
A-6 MITSUBISHI ELECTRIC
Special Register Read Write CPU Function
D8000
쏹쏹
FX
1S
FX1N
FX2N
FX2NC
FX3G
FX3U
FX3UC
Watchdog timer setting (in 1ms steps). (Writes from system
ROM at power ON) Value overwritten by program is valid
after END or WDT instruction execution. The setting must be
larger than the maximum scan time (stored in D8012).
Default value is 200 ms.
D8001
쏹
—
PLC type and system version
FX
1S: 22V
VV
FX1N/FX3G: 26V
VV
FX2N/FX2NC/FX3U/FX3UC: 24V
VV
(e. g. FX1N Version 1.00 ® 26100)
D8002
쏹
—
Memory capacity
0002 ® 2k steps (FX
1S only)
0004 ® 4k steps (FX
2N/FX2NC only)
0008 ® 8k steps or more (not for FX
1S)
If 16K steps or more "K8" is written to D8002 and "16", "32"
or "64" is written to D8102.
D8003
쏹
—
Memory typ:
00
H® RAM (Memory cassette)
01
H® EPROM (Memory cassette)
02
H® EEPROM (Memory cassette or flash memory)
0A
H® EEPROM (Memory cassette or flash memory,
write-protected)
10
H® Built-in memory in PLC
D8004
쏹
—
Error number (M)
If D8004 contains e.g. the value 8060, special relay M8060 is
set.
D8005 — —
FX
2N
FX2NC
FX3G
FX3U
FX3UC
Battery voltage (Example: "36" -> 3.6 V)
D8006 — —
Low battery voltage detection level.
Default settings:
FX
2N/FX2NC: 3.0 V ("30")
FX
3G/FX3U/FX3UC: 2.7 V ("27")
D8007 — —
FX
2N
FX2NC
FX3U
FX3UC
Momentary power failure count
Operation frequency of M8007 is stored. Cleared at
power-off.
D8008 — —
FX
2N
FX2NC
FX3U
FX3UC
Power failure detection
Default settings:
FX
2N/FX3U: 10 ms (AC power supply)
FX
2NC/FX3UC: 5 ms (DC power supply)
D8009 — —
FX
2N
FX2NC
FX3G FX3U
FX3UC
24V DC failed device
Minimum input device number of extension units and exten
-
sion power units in which 24V DC has failed.