Modbus protocol communication exception

@[toc]

One 、Modbus Protocol communication exception

• Address range

• Slave address ：1-247： Valid address range  0： radio broadcast

• Data exception （ The data cannot be parsed normally ）

• Large and small end storage problems

• Principle of exception handling （ Abnormal response ）

• The slave will reply clearly

• Function code high position  1 Pictured ：
  

• Meaning of abnormal information

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• The request frequency is abnormal

• RTU Message request interval  3.5 Character time  1.5 Character time

• Message length limit

• 0x07D0  Single request length of coil

• 0x007D  Length of register word request