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10. COMMUNICATIONS IN THE BIDIRECTIONAL MODE
MELSEC-A
10.3.2
To write data t o a special applications area i n buffer memory
(1)
Buffer memory is not battery backed up by a battery
All data in buffer memory is set to the default values when power is
turned ON or when the AlSCPU is reset.
The data changed from the default values must be written whenever the
power is turned ON or the AlSCPU is reset.
(2)
Only TO instruction can be used to write data to the special applications
area (1 00H to 11 FH).
(3) If data is written using the command in a computer program, the
AlSJ71C24 will not to operate correctly. Never try to write data using a
computer program.
If the following functions are used in combination with the dedicated
protocol, allocate the user area in buffer memory so that the same area
will not be used by different functions.
If the same area is allocated to different functions, the data in this area
is rewritten and communications will not be correctly executed.
Bidirectional mode send
Bidirectional mode receive
The memory areas preceding and following the special applications area
cannot be allocated as a single area. The areas of
OH
to FFH and 120H
to DFFH must be recognized as independent areas.
Example:
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