448
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
16 External FX Device – FNC 80 to FNC 89
16.6 FNC 87 – RS2 / Serial Communication 2
Related devices
→
For detailed explanation, refer to the Data Communication Edition.
*1.
Cleared when the PLC mode is changed from RUN to STOP.
System configuration
For using this instruction, it is necessary to attach either product shown in the table below to the main unit.
→
For the system configuration, refer to the Hardware Manual of the used PLC.
→
For detailed explanation, refer to the Data Communication Edition.
Differences between 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 a same port at the same time.
• It is not permitted to use RS (FNC 80)/RS2 (FNC 87) instruction and IVCK (FNC270)/IVDR (FNC271)/
IVRD (FNC272)/IVWR (FNC273)/IVBWR (FNC274) instruction for a same port.
Device
Name
Device
Name
ch1
ch2
ch1
ch2
M8401
M8421
Sending wait flag
*1
D8400
D8420
Communication format setting
M8402
M8422
Sending request
*1
−
−
M8403
M8423
Receiving complete flag
*1
D8402
D8422
Remaining number of data to be sent
*1
M8404
M8424
Carrier detection flag
D8403
D8423
Monitor for number of received data
*1
–
–
–
D8405
D8425
Communication parameter display
M8409
M8429
Timeout evaluation flag
D8409
D8429
Timeout time setting
−
−
−
D8410
D8430
Header 1, 2
D8411
D8431
Header 3, 4
D8412
D8432
Terminator 1, 2
D8413
D8433
Terminator 3, 4
D8414
D8434
Receiving sum (received data)
D8415
D8435
Receiving sum (calculation result)
D8416
D8436
Sending sum
D8419
D8439
Operation mode display
M8063
M8438
Serial communication error
D8063
D8438
Error code number of serial communication error
Communication type
Option
RS-232C communication
FX
3U
-232-BD or FX
3U
-232ADP
RS-485 communication
FX
3U
-485-BD or FX
3U
-485ADP
Item
RS2 instruction
RS instruction
Remarks
Header size
1 to 4 characters
(bytes)
Up to 1 character
(byte)
In 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.
In 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.