Rappel sur la requête 23 (0x17) Read/Write Multiple registers

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  • This function code performs a combination of one read operation and one write operation in a single MODBUS transaction. The write operation is performed before the read.
  • Holding registers are addressed starting at zero. Therefore holding registers 1-16 are addressed in the PDU as 0-15.
  • The request specifies the starting address and number of holding registers to be read as well as the starting address, number of holding registers, and the data to be written. The byte count specifies the number of bytes to follow in the write data field.
  • The normal response contains the data from the group of registers that were read. The byte count field specifies the quantity of bytes to follow in the read data field.
Request    
Function code 1 Byte 0x17
Read Starting Address 2 Bytes 0x0000 to 0xFFFF
Quantity to Read 2 Bytes 0x0001 to 0x007D
Write Starting Address 2 Bytes 0x0000 to 0xFFFF
Quantity to Write 2 Bytes 0x0001 to 0X0079
Write Byte Count 1 Byte 2 x N*
Write Registers Value N*x 2 Bytes
*N = Quantity to Write    
Response    
Function code 1 Byte 0x17
Byte Count 1 Byte 2 x N'*
Read Registers value N'* x 2 Bytes  
*N' = Quantity to Read    

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Quelle est le sixième caractère du mot b01g8iu ?

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