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4 FUNCTIONS
MELSEC-QnA
4.2 Communication Between the Master Station and Remote I/O Station
The overview of the communication between the master station and remote I/O station
is described.
Master station
SET Yn0
SET Yn8
FROM
TO
Programmable controller CPU
Refresh instruction
Data link startup
by E
2
PROM
parameters
Remote input
(RX)
Input
Output
Buffer memory
Remote output
(RY)
Link scan
Link scan
Remote I/O station
1
2
3
4
5
6
[Data link startup]
1
Turn on the refresh instruction (Yn0) and make the remote output (RY) data valid.
When the refresh instruction (Yn0) is off, all the remote output (RY) data is treated
as 0 (off).
2
Turn on the data link startup by the E
2
PROM parameters (Yn8), and start the data
link.
However, the parameters must be set in E
2
PROM beforehand.
When the data link is started normally, the host data link status (Xn1) turns on.
POINT
The data link can be started from the parameters written in the "parameter information area" in
the buffer memory. (Refer to Chapter 6.)