User`s manual

FX communication
RS instruction 9
9-3
9
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
D200
Address and
number of points
of send data
D 0 D500 D 1
Address and
number of points
of receive data
Pulse of Send
request
Writes contents of send
data
SET M8122
M8123
Moves receive data
RST M8123
Receive completion
Set send request
Reset receive
completion flag
For operafion refer to section 9-2, 9-3
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.
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
0N
, FX
1S
, FX
1N
, FX and FX
2C
, assure the OFF time is equivalent to or
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
2N
and FX
2NC
whose
version is earlier than V 2.00, assure the OFF time is equivalent to or longer than
100
µ
s 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
2N
, FX
2NC
whose version is V 2.00 or higher
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.