Editing Modbus (section)

====Example of a Modbus TCP/IP ADU/Modbus TCP frame in hexadecimal==== 

<code>12 34 00 00 00 06 01 03 00 01 00 01</code> 

* <code>0x12</code> and <code>0x34</code> : With transaction ID = 0x1234 (2 bytes) as a "unique number" to be identified between the Modbus TCP client/server, the transaction ID High byte is 0x12 and transaction ID Low byte is 0x34
* <code>0x00</code> and <code>0x00</code> : Protocol identifier high byte and low byte
* <code>0x00</code> and <code>0x06</code> : Length high byte and low byte. The length is 6 bytes which includes: unit identifier (slave address) (1 byte), function code (1 byte), high byte of the register address to read (1 byte), low byte of the register address to read (1 byte) and data (2 bytes = high byte and low byte of the number of registers to read)
* <code>0x01</code> : Unit identifier (slave address)
* <code>0x03</code> : Function code (Read Multiple Holding Registers)
* <code>0x00</code> and <code>0x01</code> : high byte and low byte of the register address to read. The register address to read in this case is <code>0x0001</code>.
* <code>0x00</code> and <code>0x01</code> : high byte and low byte of the number of registers to read. The number of registers to read in this case is <code>0x0001</code>. (i.e 1 register)