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8.
COMMUNICATIONS USING DEDICATED PROTOCOLS
MELSEC-A
8.1 4.2
On-Demand function control procedure
(1)
A I S C P U control procedure
On-demand data
Check (and if necessary change) the contents of buffer
Set transmission data
memory address 103H. See Examples 1 and 2 in Sec-
.
.
.
.
.
. .
tian 8.1 4.3 for transmission data formats when word or
byte units are selected.
Write the data to be transferred
Write to buffer memory address
O H
to FFH or 120H to
to the user memory area.
DFFH ('1)
Clear the on-demand buffer memory address lOCH.
(Start is disabled if the contents of this address are "1
'.)
Write the head address where the data is stored to buff-
Start on-demand
.......
er memory address 109H and the data length to ad-
dress 10AH.
If ''1' is wrinen to buffer memory address IOCH,
an
Transmission error check
. . . . . . . .
error occurs and the data is not transmilied.
-
Error
I
No error
*1
If data communications is executed at the same time in
either the no-protocol mode or the bidirectional mode,
the area must not overlap with the following area.
Transmission completed
.
No-protocol send area (bidirectional send
area)
.
No-protocol receive area (bidirectional receive area)
(2)
Computer control procedure
On-demand data receive
+
The AlSJ71C24 appends "FE" as the PC CPU number.
was received due to on-
........
Process data as on-demand data only if the PC CPU
number of the received data is FE.
Set transmission data
Receive completed
C
Z
e
I
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