F-85
FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
12 Related Data
12.2 Details of related devices (RS instruction)
A
Common Items
B
N:N Network
C
Parallel Link
D
Computer Link
E
Inverter
Communication
F
Non-Protocol
Communication
(RS/RS2 Instruction)
G
Non-Protocol
Communication
(FX
2N
-232IF)
H
Programming
Communication
I
Remote
Maintenance
Apx.
Discontinued
models
12.2 Details of related devices (RS instruction)
This section explains devices used during non-protocol communication.
12.2.1 Serial communication error [M8063]
This device turns ON when an error occurs during serial communication.
1. Detailed contents
This device works as the serial communication error flag.
When this device turns ON, a corresponding error code is stored in D8063.
2. Cautions on use
The serial communication error flag does not turn OFF even after communication recovers its normal status.
Serial communication errors are cleared in FX
3G, FX3U and FX3UC PLCs when the power is turned off and on.
Serial communication errors are cleared in other PLCs when the mode is switched from STOP to RUN.
12.2.2 Communication setting keep [M8120]
Set this device to ON in a sequence program so that the communication setting is kept (for FX0N PLCs).
1. Detailed contents
In FX0N PLCs, set M8120 to ON in a sequence program so that the communication format setting is kept.
2. Cautions on use
In FX0N PLCs, the communication setting status is kept only when M8120 is set to ON.
In any PLC other than the FX
0N PLCs, setting of M8120 is not required.
12.2.3 Sending wait flag [M8121]
This device remains ON while the PLC is waiting to send.
1. Detailed contents
• In full-duplex communication in FX3G, FX3U and FX3UC PLCs
While the control line is set to the standard or interlink mode in a communication parameter, when the
control line DR (DSR) turns OFF while sending data, the PLC waits to send and M8121 turns ON.
• In full-duplex communication in all PLCs except FX
3G, FX3U and FX3UC PLCs
M8121 does not turn ON.
• In half-duplex communication
When the sending request device is set to ON while data is being received, the PLC waits to send and
M8121 turns ON.
12.2.4 Sending request [M8122]
When this device is set to ON by the SET instruction, the PLC starts to send.
1. Detailed contents
When this device is set to ON by the SET instruction, the PLC starts to send. When sending is completed, this
device is automatically set to OFF.
2. Cautions on use
When setting this device to ON, set the drive condition in the pulse type.
In FX2(FX), FX2C, FX1S, FX0N, FX1N, FX1NC, and FX2N (before Ver. 2.00) PLCs, note the following contents:
• While the PLC is receiving data, next data is sent after the receiving is finished. During this period, the
sending wait flag remains ON.
• From when the head data is received until the receiving complete flag turns ON, it is regarded as data is
being received. If a sending request is given while the head data is being received, data is confused.
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