Manage Number Of Writes 2 (Write Life = Arbitrary Number Of Writes) - Mitsubishi MELSEC-Q EQ-V680D1 User Manual

5. THINGS YOU NEED TO KNOW BEFORE PROGRAMMING

5.4.2 Manage Number of Writes 2 (Write life = Arbitrary number of writes)

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The three bytes from the ID tag head address serve as the number of writes
management area.
When the difference that results from subtraction of the number of writes is written in
this area and the value is smaller than 0, the number of writes is exceeded, the status
flag (bit 4) of the error details storage area (Un\G41, Un\G4041) turns ON, and error
detection (X5, XD) turns ON.
Accordingly, to manage the number of writes, the write life needs to be entered in
advance in the management area.
The EEPROM-type ID tag write life is 100,000 (0186A0
to a number less than or equal to that value.
When the data of the management area have already reached 0, the value of the
management area is not updated.
Area head
address
(1) Method of use
An arbitrary write life is written in advance in the ID tag number of writes
management area using the Write command.
Since the ID tag write life is determined for each block (8 byte) unit, the number of
writes of the address within the block in which data are most frequently written
needs to be counted.
When data are written in the address in which data are most frequently written, the
number of writes is updated, enabling verification of the write life.
The number of writes can also be verified without updating the number of writes.
Write stage
Update number
Life verification
stage
ID tag
Upper digit
3 bytes
Middle digit
Lower digit
Write data
of writes
Verify life
). Be sure to set the write life
H
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