Mitsubishi Electric MELSEC FX3U Programming Manual page 759

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Caution
1. 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 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 number of
times of writing to the memory. Make sure not to exceed the allowable number of writes.
• In FX PLCs
3G
Data can be written to the memory cassette (EEPROM) up to 10,000 times, and to the built-in memory
(EEPROM) up to 20,000 times.
Every time the RWER (FNC294) 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)instruction is not counted as a write to the memory.
Errors
An operation error is caused in the following cases; The error flag M8067 turns ON, and the error code is
stored in D8067.
• When the last device number to be transferred exceeds "32767" (error code: K6706)
At this time, devices up to the last one (R32767) are read and transferred.
• When a memory cassette is not connected (error code: K6771)
*1. An operation error is not caused in FX
in the EEPROM built in the PLC are read if a memory cassette is not connected.
Program example
In the program example shown below, the contents (current value) of 4000 extension file registers ER1 to
ER4000 inside the memory cassette are read, and transferred to 4000 extension registers R1 to R4000 inside
the built-in RAM.
M0
FNC290
LOADR
Extension file registers (ER)
inside memory cassette
Device Current
number value
ER1 K100
ER2 K50
ER3 H0003
ER4 H0101
ER3999 K55
ER4000 K59
PLCs
3G
R1 K4000
Extension registers (R)
inside built-in RAM
Read
(transfer)
R1
R2
R3
R4
R3999
R4000
33 Extension File Register Control – FNC290 to FNC299
*1
PLCs because the contents of extension file registers stored
Device Current
number value
K100
K50
H0003
H0101
K55
K59
33.1 FNC290 – LOADR / Load From ER
31
32
33
34
35
36
37
38
A
B
757