Mitsubishi Electric FX3U-232-BD User Manual page 604

FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
6.3.2 FX (Ver. 2.00 or later), FX
2N
FX PLCs Ver. 2.00 or later, and FX
2N
bidirectional communication. When executing half-duplex, bidirectional communication, pay attention not to
set the sending request to ON while receiving. If the sending request is set to ON, the PLC starts to send. As
a result, the external equipment may not be able to receive data, and the sent and received data may be
destroyed.
In full-duplex, bidirectional communication, the sending wait flag M8121 does not turn ON.
In FX , FX , FX
3S 3G
DR (DSR) is OFF, the PLC waits to send, and the control line is in the standard mode or interlink mode.
1. Without control line
RS
instruction
OFF ON
driving
SD (TXD)
Send data
Sending
request
M8122
RD (RXD)
Receive data
Receiving
complete
M8123
2. When the control line is in the standard mode
Use this mode when only sending or receiving.
The control line and transfer sequence are equivalent to those in FX
Subsection 6.3.1.
3. When the control line is in the modem mode
RS
instruction
OFF
driving
SD (TXD)
Send data
Sending
OFF
request
M8122
ER (DTR) OFF
RD (RXD)
Receive data
Receiving
complete
M8123
DR (DSR) OFF
F-54
, FX
2NC
2NC
, FX and FX
3GC 3U 3UC
Message
1
OFF ON
Message
2
OFF
Receiving wait status is
started.
ON
Message
1
ON
ON
Message 2
OFF
ON
, FX , FX , FX
3S 3G 3GC
, FX , FX , FX , FX
3S 3G 3GC
PLCs, however, the sending wait flag M8121 remains ON while the
Message
3
Message 4
ON
Reset it in a sequence program.
While it remains ON, the PLC cannot receive the next set of data.
Message 3
ON
Reset it in a sequence program.
While it remains ON, the PLC cannot receive the next set of data.
6 Creating Programs (RS Instruction)
6.3 Operation of Control Line
and FX PLCs
3U 3UC
and FX PLCs execute full-duplex,
3U 3UC
Message
5
ON
PLCs (before Ver. 2.00). Refer to
2N
Message 4
ON