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10.
COMMUNICATIONS IN THE BIDIRECTIONAL MODE
MELSEC-A
10.2
Handshake Signals and Buffer Memory
D
(1) Handshake signals in the bidirectional mode
Signals known as I10 handshake signals are required for communica-
tions in the bidirectional mode.
These signals output data received from the sequence program to a
computer or detect signals from an external device to enable the
sequence program to read them,
PC CPU
1
Computer
Computer
i
PC CPU
Signal
X n O
(Send
completed)
X n l
(Received
data
read
request)
Y
+
I
1
(Receive
data read
complete)
Timing
Turned OFF by program
Turned ON by program
Turned OFF by
AJ71C24
Turned O N by AJ71C24
Turned OFF by A J 7 r C 2 4
Turned ON by AJ71CZ4
Turned OFF by program
Turned ON by program
The number 'n" appended to X and Y is determined according to the
position where the AJ71C24 is loaded and the number of I10 modules
loaded prior to this module. If this module (AJ71C24) is loaded at slot
0 in a base module, XnO is expressed as 'XO'.
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