Mitsubishi Electric MELSEC-A Manual Book page 93

6. COMMUNICATIONS IN THE BIDIRECTIONAL MODE
MELSEC-A
6.4.4
O u t l i n e
of receiving
data from the PC
CPU
in
the
bidirectional
mode
The figure below outlines the flow of data transmission from the PC CPU in
the bidirectional mode described in Section
6.4.3.
xo
-
The X0 Is turned
on.
The X1 Is turned on.
x1
When
the
X0 Is turned
o n ,
the PC
CPU
w t r r
the s m n d data 'ABCDE-
FGH'
t o
the data registers D l to
D4.
When
the X1
Is
turned on, the PC
CPU turns on the request-to-send
signal (Yea).
2) Data is
I n r u m i n d .
4)
Transmisslon
1)
The PC CPU writes data to the buffer memory in the AJ71UC24 in re-
2) As soon as the request-to-send signal (Y90) is turned on, the AJ71 UC24
3) The computer checks the received data, and sends back a response
4)
On receipt of the response, the AJ71UC24 turns
on
the transmission
sponse to the TO instruction from the sequence program.
transmits the data as it is to the computer.
(receiving result) to the
AJ71
UC24.
completed signal (X80) to complete a cycle of data transmission.
Slop 0
END
Slap0
Sequence
PrWram
PC CPU
AJ71 UC24
slgnal ( Y W )
Transmlssion
signal (X80)
I
Computer