Programming instructions

98
14.2 Special D Registers
The addresses D8000 and above are reserved for system use. In the
FX1S/1N/2N/2NC, the range is D8000-D8255. In the FX3U, the range is D8000-
D8511. These registers have various system functions. The complete list of
special D registers is found in the FX3U Programming Manual in Chapter 36. It
can also be found in the GX-Developer software in the help menu.
A few of the diagnostic register available
D8004 Error relay active (i.e. 8064 indicate M8064 active)
D8006 Low battery fault alarm level
D8010 Present scan time
D8064 ~ D8068 Error codes
D8064 – Parameter error code
D8065 – Syntax error code
D8066 – Program error code
D8067, 68 – Operation error code
D8069 Error step number
The following registers aren’t diagnostic registers per se, but provide useful
information or functions.
D8001 PLC type and firmware revision
D8005 Battery voltage (actual)
D8013 ~ D8019 Real-time clock
D8013 Seconds
D8014 Minutes
D8015 Hours (24 hour format)
D8016 Day
D8017 Month
D8018 Year (2 digits 00-99)
D8019 Day of Week (0 Sunday – 6 Saturday)
D8020 Input Filter (range is 0-60)
0 = 5μs to 200μs (varies by address)
# = #ms
14.3 Handy Troubleshooting Circuits
This circuit indicates that the battery voltage is low.
The alarm bit turns on an output that can activate a light, buzzer, etc.