Mitsubishi Electric MELSEC-L LD75D, User Manual

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13.3
Execution Data Backup Function
When the LD75 buffer memory data is rewritten from the CPU module, "the data backed up in the LD75 flash ROM"
may differ from "the data (buffer memory data) for which control is being executed". In cases like these, the data being
executed will be lost when the programmable controller power is turned OFF. (

Page 305, CHAPTER 7)
In cases like these, the "execution data backup function" backs up the data being executed by writing it to the flash
ROM. The data that was backed up is then written to the buffer memory when the power is turned ON next.
The details shown below explain about the "execution data backup function".
• Execution data backup means
• Control details
• Control precautions
• Execution data backup method
(1) Execution data backup (written to flash ROM) means
• The backup is executed with a program.
• The backup is executed by GX Works2.
Refer to

GX Works2 Version 1 Operating Manual (Common) for execution data backup method by GX
Works2.
(2) Control details
The following shows the data that can be written to the flash ROM using the "execution data backup function".
(3) Control precautions
• Parameter initialization is only executed when the positioning control is not carried out (when the PLC
READY signal [Y0] is OFF). The warning "In PLC READY (warning code: 111)" will occur if executed when
the PLC READY signal [Y0] is ON.
• Writing to the flash ROM can be executed up to 100,000 times. If writing to the flash ROM exceeds 100,000
times, the writing may become impossible, and the error "Flash ROM write error" (error code: 801) will occur.
• After one power ON/CPU module reset operation, writing to the flash ROM using a program is limited to up
to 25 times.
Do not turn the power ON/OFF; reset the CPU module, etc., while writing to the flash ROM.
If the power is turned OFF or the CPU module is reset to forcibly end the process, the data backed up in the flash ROM will
be lost.
Buffer memory Flash ROM
Parameters ([Pr.1] to [Pr.57], [Pr.70], [Pr.150])

Parameters ([Pr.1] to [Pr.57], [Pr.70], [Pr.150])
Positioning data (No. 1 to No. 600) Positioning data (No. 1 to No. 600)
Block start data (No. 7000 to 7004) Block start data (No. 7000 to 7004)
If the 26th writing is executed, the error "Flash ROM write number error" (error code: 805) will occur. If this
error occurs, carry out the power OFF

ON/CPU module reset operation again.
Refer to [Md.19] of

Page 114, Section 5.1.7 for details.