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4. Parameter description
Parameter
Message
Details
①
Address
Setting range: 0~254, 0 is the broadcast address, the address of inverter is from 1
to 254.
P.36 can set the address of inverter. When the PC send information from the
inverter and the inverter return information to PC, P.36 must be set.
②
Function
SE2-type inverters have three functions. The inverter operated according to the
request of the PC, the PC setting function of the table other than the code, the
inverter will return an error response. Response returned from the inverter in
normal response returns to normal function, when returns the error response the
function code should add H80.
Function name
Function code
Details
Read multiple
registers
H03
From the PC may read straight registers
to inverter.
Write single
register
H06
From the PC may write a single register
to inverter.
Write multiple
registers
H10
From the PC may write straight
registers to inverter.
③
Data
According to the function code, the data will change. Data includes the start
address, the number of register and the write message.
④
Error check
ASCII mode is for the LRC checksum, RTU mode is for the CRC checksum. (On
LRC, CRC checksum algorithm detailed instructions please refer to the standard
Modbus protocol specification).
Algorithm of LRC checksum:
LRC check is relatively simple to use. It in ASCII mode to detect the message except the
beginning of the colon field and the end of the carriage return line number. It is only necessary to
transmit the data of each byte stack, and if the result is greater than hexadecimal H100, after removal
of the excess (such as: the results obtained for the hexadecimal H136, only to take H36) can be
reversed then plus 1.
Algorithm of CRC checksum:
1. Installation of a 16-bit register, all bits are 1.
2. The 16-bit operation result which exclusive OR between the 16-bit register high byte and the
beginning of 8-bit byte was put into the register.
3. The 16-bit register move 1-bit towards of the right.
4. If the number right (mark bit) out of the digital is 1, exclusive OR between the generator
polynomial “1010000000000001” and the register operated”, if the number right out of the bit is 0,
then return to the step 3.
5. Repeat step 3 and 4, until out of the 8-bit.
6. Exclusive OR between another 8-bit and this 16-bit register.
7. Repeat from step 3 to 6, until all bytes of the packet have exclusive OR the 16-bit register, and
shift 8 times.
8. The 2 byte CRC error checking of the 16-bit registers that was added to the most significant bit of
the message.