Mitsubishi FX3U-USB-BD User Manual page 544

FX Series PLC User's Manual - Data Communication Edition
Non-Protocol Communication (RS/RS2 Instruction)
5. Cautions on receiving
When receiving data, observe the following cautions
1) While the receiving complete flag is ON, the PLC cannot receive the next set of receive data.
When the receiving complete flag is set to OFF, the PLC waits to receive.
2) Set the amount of received data to a value including "terminators", "sum check" and "CR+LF".
If the specified amount of received data is small, the serial communication error flag (M8062, M8063 or
M8438) turns ON.
F-64
8 Creating Programs (RS2 Instruction)
8.2 How to Use RS2 Instruction