Cautions On Using Extension File Registers - Mitsubishi Electric MELSEC FX3U Programming Manual

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition

4.10.7 Cautions on using extension file registers

1. Cautions on writing data to extension file registers (FX
Because extension file registers are stored in the flash memory inside a memory cassette, pay attention to
the following points:
• When writing data to extension file registers by SAVER instruction
Initialize sectors to be written before executing this instruction. After initialization, store data to be written
to extension registers.
In FX PLCs Ver.1.30 or later, it is not necessary to initialize sectors to be written when using RWER
3UC
instruction.
• When writing data to extension file registers by LOGR instruction
Initialize sectors to be written before starting to log data.
• When using INITR instruction
This instruction initializes the contents of specified extension registers and extension file registers.
When initializing only extension file registers by this instruction, make sure to temporarily move the
contents of extension registers to unused extension registers or unused data registers before executing
this instruction.
When initializing only extension file registers in FX
2. Initialization of extension file registers
Because the contents of extension file registers are stored in the memory cassette or built-in EEPROM, use
the data clear operation in a sequence program or GX Developer to initialize them.
For writing data to extension file registers in FX
be written in advance.
For writing data to extension file registers in FX
written in advance.
1) When initializing extension file registers in a program (required only in FX
a) Initializing only extension file registers in sector units [Ver.1.30 or later]
Example: When initializing ER0 to ER4095 (initializing two sectors starting from ER0)
Command input
b) Initializing extension registers and extension file registers in sector units
Example: When initializing R0 to R4095 and ER0 to ER4095 (initializing two sectors starting from R0
and ER0)
Command input
2) When initializing extension file registers using GX Developer
Select [Online] → [Clear PLC memory...] in GX Developer, and clear [Data device].
This operation initializes the contents of timers, counters, data registers, file registers and extension
registers.
3. Allowable number of writes to the memory
Note the following cautions on access to extension file registers.
• In FX /FX
3U 3UC
Data can be written to the memory cassette (flash memory) up to 10,000 times.
Every time the INITR (FNC292), RWER (FNC294) or INITER (FNC295) instruction is executed, it is
counted as a write to the memory. Make sure not to exceed the allowable number of writes.
When a continuous operation type instruction is used, data is written to the memory in every operation
cycle of the PLC. For preventing this, make sure to use a pulse operation type instruction.
Execution of the LOADR (FNC290), SAVER (FNC291) or LOGR (FNC293) instruction is not counted as a
write to the memory. However, it is necessary to initialize the writing target sector before executing the
SAVER (FNC291) or LOGR (FNC293) instruction.
Every time the INITR (FNC292)or INITER (FNC295) instruction is executed, it is counted as a write to the
memory. Make sure not to exceed the allowable number of writes.
FNC 295
R0
INITERP
FNC 292
R0
INITRP
PLCs
4.10 Extension Register [R] and Extension File Register [ER]
/FX
3U 3UC
PLCs Ver.1.30 or later, use INITER instruction.
3UC
/FX PLCs, it is necessary to initialize the target area to
3U 3UC
PLCs, it is not necessary to initialize the target area to be
3G
The current value is initialized to "FFFF
K2
to ER4095.
The current value is initialized to "FFFF
K2
ER0 to ER4095.
4 Devices in Detail
PLC)
/FX PLCs)
3U 3UC
" in ER0
H
" in R0 to R4095 and
H
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