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FX3S/FX3G/FX3GC/FX3U/FX3UC Series
Programming Manual - Basic & Applied Instruction Edition
16 External FX Device – FNC 80 to FNC 89
16.8 FNC 87 – RS2 / Serial Communication 2
11
FNC30-FNC39
Rotation and
Shift
12
FNC40-FNC49
Data Operation
13
FNC50-FNC59
High-Speed
Processing
14
FMC60-FNC69
Handy
Instruction
15
FNC70-FNC79
External FX I/O
Device
16
FNC80-FNC89
External FX
Device
17
FNC100-FNC109
Data
Transfer 2
18
FNC110-FNC139
Floating Point
19
FNC140-FNC149
Data
Operation 2
20
FNC150-FNC159
Positioning
Control
Differences between the RS (FNC 80) instruction and RS2 (FNC 87) instruction
Cautions
→ For other cautions, refer to the Data Communication Edition.
• Do not drive two or more RS (FNC 80) and/or RS2 (FNC 87) instructions for the same port at the same time.
• It is not permitted to use an "RS (FNC 80)/RS2 (FNC 87)" instruction and an "IVCK (FNC270) to IVMC (FNC275)",
"ADPRW (FNC276)", "FLCRT (FNC300) to FLSTRD (FNC305)" instruction for the same port.
• When using a header and terminator, set the data in the header and terminator to corresponding special data
register (D) before executing the RS2 instruction. Do not change the values of the header and terminator while the
RS2 instruction is being executed.
Function Changes According to Versions
The function of the FNC 87 instruction varies depending on the PLC version shown in the table below.
Item RS2 instruction RS instruction Remarks
Header size 1 to 4 characters (bytes) Up to 1 character (byte)
For the RS2 instruction, up to 4 characters (bytes) can be
specified as a header or terminator.
Terminator size 1 to 4 characters (bytes) Up to 1 character (byte)
Attachment of
check sum
The check sum can be
automatically attached.
The check sum should be
attached by a user
program.
For the RS2 instruction, the check sum can be
automatically attached to the sent and received data.
In this case, however, make sure to use a terminator in the
communication frame to be sent and received.
Used channel
number
ch0, ch1, ch2 ch1
For the RS2 instruction:
Ch0 is available only in FX3G/FX3GC PLCs.
Ch2 is not available in FX3G PLC (14-point and 24-point
type) and FX3S PLC.
Compatible Versions
Item Function Summary
FX3S FX3G FX3GC FX3U FX3UC
Ver. 1.00
or later
Ver. 1.00
or later
Ver. 1.40
or later
Ver. 2.30
or later
Ver. 2.30
or later
ch1
Data Set Ready (DSR) Flag
Turns M8405 ON when the DR (DSR)
signal of ch1 is ON.
ch2
Data Set Ready (DSR) Flag
Turns M8425 ON when the DR (DSR)
signal of ch2 is ON.