25
3) Choose the verification method
Press Shift + 0 to enter the main menu, the load will display "MENU CONFIG", press Enter to confirm, then
the load will enter the config configuration menu, press up and down until the load shows "CONFIG
COMM.PARITY" Enter to enter, the load display "COMM.PAR xxxxx" prompts the current calibration mode, the
user can use the up and down keys to select the appropriate calibration method, and press Enter to confirm.
The current load only supports no parity, odd parity, even parity, a total of three kinds of calibration options.
4.8.2 Select the communication baud rate
Press Shift + 0 to enter the main menu, the load will display "MENU CONFIG" and press Enter to confirm.
At this moment, the load will enter the config configuration menu, press the up and down keys until the load
shows "CONFIG BAUDRATE SET", prompt to select baud rate and press Enter Enter, at this moment the load
shows "BUADRATE xxxxx", prompting the current baud rate, the user can use the up and down keys to select
the baud rate for your own, and press Enter to confirm.
The current load only supports
2400,9600,14400,28800,57600,115,200 total of 6 baud rate options.
4.8.3 Data
In some command frames, the data is fixed-length, but in some other frames, the data is indefinitely long.
Following the Modbus protocol, the hexadecimal data in the data field, as well as the floating-point numbers,
are high byte first and low byte last. In addition, in the write coil output value, the data must be 0x0000 and
0xFF00, where 0x0000 means the position is zero and 0xFF00 means the position 1.
4.8.4 Function Code
Function code is single-byte hexadecimal data, currently only open the following four kinds of functional
modes
function code
Description
0x01
Read coil, read data bit by bit
0x05
Write coil, write data bit by bit
0x03
Read register, read data by word addressing
0x10
Write register, write data by word address
4.8.5 Error checking
Load using cyclic redundancy check (CRC), CRC results for the word, the low byte first, high byte in the
back. Its generation rules are as follows.
a)
Set a 16-bit CRC register and assign 0xFFFF.
b)
The first byte in the data frame, that is, the additional address, is bitwise XOR'ed with the lower 8 bits of
the CRC register and stored in the CRC register.
c)
Moves the CRC register to the right by 1 bit and detects if the least significant bit is shifted out. If the least
significant bit is 1, the CRC register is XOR'd with the fixed value 0xA001.
d)
Repeat step c for 8 times.
e)
Repeat steps b, c, d for the next byte of the data frame up to the last data in the data field.
f)
The contents of the last CRC register, the last check value, are appended to the last data in the data frame,
keeping the lower 8 bits first and the upper 8 bits later.
4.8.6 Complete command frame parsing
Read the coil
