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7. INITIAL SETTING OF TRANSMISSION CONTROL DATA TO
BUFFER MEMORY
MELSEC-A
7.4.4
Setting a buffer memory area for no-protocol send
This section describes how to set the AlSJ71 C24 buffer memory area to store
data transmitted from the PC CPU to an external device in the no-protocol
mode and gives an example.
When the bidirectional mode settina area (address 112H) is set to "1". this
memory area is set for bidirectionalmode t;ansmission.
etting methodl
1
Write the head address in hexadecimal
104H (Head address setting)
(Default
:
OH)
105H (Buffer size setting)
(Default : 80H)
Write the memory size (number of
addresses) in hexadecimal.
POINTS
(1) Buffer memory addresses lOOH to 11FH are for the special applica-
tions area and should not be set.
(2) When other kmds ot devices are also used, make sure that the
specified range does not overlap the no-protocol receive area or the
on-demand data area.
I
(3)
Buffer memory address 105H should include the storage area of the
no-protocol send data length.
(4) If any range except the user area is set, the AlSJ71C24 will execute
operations with defaults including the areas mentioned in (2) above.
xample
1
To set the head address to 120H and the memory size to 100H (AlSJ71C24 I/O addresse!
80 to QF).
Sequence Program
Write H120 to buffer memory address 104H.
HI05
HI00
Write HI00 to buffer memory address 105H.
Address
Buffer memory
OH
, F = 4
for the noprotocol
send
Bunel memow area for
Shows that the head address is 120H.
Shows that the memory size is 100H.
I
Area for no-protocol send (100H addresses)
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