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9-6
Chapter 9. User-defined Addresses
z
Precautions when using both the normal memory area and the RAM area for the
same parameter
After data is written to the RAM area, if a value different from the RAM area is
written to the normal memory area, the value will be retained even if a power loss
occurs.
However, after data is written to the RAM area, if the same value as the RAM area
is written to the normal memory area, the value will not be retained if a power loss
occurs.
Note
•
For detailed operation examples, see
Communication Function (p. 14-10).
Also, note the following information.
•
The SLP-C7 Smart Loader Package writes to the normal memory area.
•
PLC link communication can be set to write to either the normal memory area or
the RAM area.
The following methods are available for writing the same value to the normal
memory area as the value written to the RAM area.
•
Method 1:
Write a value to the RAM area, write a different value to the RAM area, and then
write the same value to the normal memory area as was first written to the RAM
area.
Example: Write 100 to the RAM area. → Write 101 to the RAM area. → Write 100
to the normal memory area.
This writing method is complex, but it allows the C7G to continue control.
Because the number of writing cycles to the normal memory area is less than in
Method 2, this method is beneficial in terms of the EEPROM writing life span.
•
Method 2:
Write a value to the RAM area, write a different value to the normal memory
area, and then write to the normal memory area the same value as was written to
the RAM area.
Example: Write 100 to the RAM area. → Write 101 to the normal memory area. →
Write 100 to the normal memory area.
This writing method is complex, but it allows the C7G to continue control.
•
Method 3:
Turn the power of the C7G off and on again, and then write to the normal
memory area.
This writing procedure is simple, but a power operation is required that
interrupts control by the C7G. Care is also required because operation after
turning the power on again starts with the value written in the normal memory
area before the power loss.