Operation Of Rs Instruction - Mitsubishi Electric MELSEC FX Series User Manual

FX communication
9.1.2

Operation of RS Instruction

An RS instruction specifies the head address and the number of points of the send data sent
from a programmable controller as well as the head address for receive data save destination
and the maximum acceptable number of points of receive data.
The data send/receive sequence using an RS instruction is described below.
X010
FNC 80
R S
Pulse of Send
request
Writes contents of send
data
SET
Set send request
Receive completion
M8123
RST
Reset receive
completion flag
Note:
Though an RS instruction can be used in a program as many times as you want,
make sure that only one RS instruction is driven at any one time (Two or more RS
instructions cannot be turned on at one time.). For changeover, assure the OFF
time is equivalent to or longer than one cycle time.
In the FX
longer than two scan times between completion of send and the start of receive or
between completion of receive and the start of send. In the FX
version is earlier than V 2.00, assure the OFF time is equivalent to or longer than
100 µs between completion of send and start of receive or between completion of
receive and start of send. (Refer to Paragraph 9.2.1.)
This OFF time is not required in the FX
because full duplex communication is enabled.
While an RS instruction is driven, modification to D8120 is not accepted. Turn OFF
the RS instruction, then modify the setting.
D200 D 0 D500
Address and Address and
number of points
number of points
of send data of receive data
M8122
Moves receive data
M8123
, FX , FX
0N 1S 1N
For operafion refer to section 9-2, 9-3
D 1
Writes the contents of D0 (number of
points of send data) and D200~.
This request is automatically reset
when send is completed. Never reset
this request by a program.
Transfers the receive data to the
dedicated save area.
The receive completion flag M8123
should not be reset in a program of
continuous operation.
, FX and FX , assure the OFF time is equivalent to or
2C
, FX
2N 2NC
RS instruction 9
and FX
2N
whose version is V 2.00 or higher
9
whose
2NC
9-3