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App. - 34 App. - 34
MELSEC-Q
APPENDIX
Appendix 9.2 When accessing buffer memory using sequence program
In the following program example, data are read from or written to the buffer memory of
the Q series C24 using the REMFR/REMTO instruction.
POINT
Use GX Configurator-SC to change the default value of the buffer memory. Using
GX Configurator-SC, save the new setting value to the flash ROM of the Q series
C24. (Refer to Chapter 8.)
(1) Program conditions
The following program reads data from or writes data to the QJ71C24N buffer
memory (CH1 side word/byte units designation area) when the read/write
command (X1020, X1021) turns ON.
(a) Devices used
:
• Read/write command.............................................................. X1020, X1021
• Read/write command pulse signal ......................................... M10, M11
• Completion device for REMFR/REMTO instruction .............. M100 to 103
• Normal/abnormal completion flag for REMFR/REMTO
instruction................................................................................ M200 to 203
• Read from word/byte units designation area ......................... D0
• Write to word/byte units designation area.............................. D1
(2) Program examples
(a) Read from buffer memory
<Read command>
Changes the read command
into pulses.
Abnormal completion of
REMFR instruction
Normal completion of
REMFR instruction
Reads the word/byte units
designation area data of the
buffer memory to D0.
(b) Write to buffer memory
<Write command>
<Write command>
Abnormal completion of
REMTO instruction
Changes the write command
into pulses.
Sets the word/byte units
designation to byte.
Transfers the setting value to
the word/byte units designation
area of the buffer memory.
Normal completion of
REMTO instruction