Important Points In Creating Programs - Mitsubishi Electric FX3U-232-BD User Manual

FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
8.4

Important Points in Creating Programs

1) The RS2 instruction can be used as many times as necessary in a program, but make sure that only one
RS2 instruction is driven in each communication port at a time.
For multiple RS instructions to be driven, make sure the OFF time is longer than one scan time.
2) Do not use another instruction (such as a RS instruction or IVDR instruction) which uses the same
communication port. If such an instruction is used, communication may not function normally.
3) While a RS2 instruction is being driven, change of D8370, D8400 or D8420 is prohibited.
To change D8370, D8400 or D8420, set the RS2 instruction to OFF, set D8400 or D8420 to "0", and then
set a new value to D8400 or D8420.
4) In the interlink mode, set the amount of received data "n" to "31" or more.
If it is set to "30" or less, the control line ER (DTR) is set to OFF as soon as the PLC receives data.
5) FX , FX
3S 3G
using half-duplex, bidirectional communication, pay attention not to turn ON the sending request flag
while receiving.
6) When using the header and terminator, set them before driving the RS2 instruction. Do not change the
setting while the RS2 instruction is being driven.
7) When RS-485 communication is executed in FX
starts receiving after it has completed sending.
Assure 300 s or more in counterpart equipment as the period from completion of receiving to start of
sending.
8.5 Communication Error
When a communication error occurs, the error flag M8062 turns ON during communication using ch0, the
error flag M8063 turns ON during communication using ch1, or the error flag M8438 turns ON during
communication using ch2. D8063 or D8438 stores the error code respectively.
D8062 (ch0) D8063 (ch1)
6201
6202
6203
6204
6205
6206
, FX , FX and FX
3GC 3U 3UC
Error code
D8438 (ch2)
6301 3801
6302 3802
6303 3803
6304 3804
6305 3805
6306 3806
PLCs execute full-duplex, bidirectional communication. When
PLCs, it may take 300 s until the PLC
and FX
3U 3UC
Description
Parity error, overrun error or framing error
Defective communication character
Receive data sum mismatch
Defective data format
Defective command
Monitoring timeout
Confirm the contents in "Chapter 11. Troubleshooting".
8 Creating Programs (RS2 Instruction)
8.4 Important Points in Creating Programs
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