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6. MODE SWITCHING METHODS
MELSEC-A
(2)
This section shows how to w i t c h from a no-protocol/bidirectional mode
to a dedicated protocol mode.
b
Data communications
'
can be done in the
I
switched mode.
External device
A1 SJ71 C24
Initial processing
t
(about 4 seconds)
'
A1 SJ71 C24 READY
signal (Xn7)
I
Value at buffer
address 11 9H
0005H
O O O O H
r
Sequence program
E d
The operations
and
processing of the signals timings given i n the figure
are explained below.
Use a PC CPU to write the mode number to be switched to the mode
switching specification area (buffer address 119H) of the
AlSJ71 C24.
I
Number ofthe mode to be switched (see Section
4.3.1)
Example: dedicated protocol mode 1
Use the PC CPU t o turn ON the mode switch request signal
(Y(n+1)9).
The AlSJ71C24 turns the READY signal (Xn7) of the self OFF and
executes the following mode switching processing.
The mode of the AlSJ71C24 is switched.
The value of the special-applications area of the AlSJ71C24
buffer is returned to a default value (excluding the mode
switching specification area [buffer address 11 9H1).
After completing 2) above, the AlSJ71C24 turns the READY signal
(Xn7) and mode switch completed signal (Xn9) ON.
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