Crc Check; Register Address Distribution - Veikong VFD500 Series Operation Manual

VFD500 high performance vector control frequency inverter user manualAppendix A
request (such as the register address does not exist, etc.), the slave station will return an
abnormal response to inform the master of the actual situation.
Abnormal response command code = normal response command code + 0x80,
Abnormal code value and meaning as shown in the following table
Error
code
0x01 Invalid command code/error
function code
0x02 Error data address/Illegal
register address
0x03 wrong frame format
0x04 Data is out of range
0x05 Reading request refuse
A.5 CRC check
CRC（Cyclical Redundancy Check）use RTU frame，The message includes an error detection field
based on the CRC method. The CRC field examines the contents of the entire message. The CRC field
is two bytes containing a binary value of 16 bits. It is calculated by the transmission equipment and
added to the message. The receiving device recalculates the CRC of the received message and
compares it with the value in the received CRC field,If the two CRC values are not equal, there is an
error in the transmission.There is a lot of information on the Internet about CRC checking it is not
elaborated hereabout CRC check code generation algorithm,
A.6 Register address distribution
The register address of VFD500 is 16-bit data, the upper 8 bits represent the function code group
number, the lower 8 bits represent the group number, the upper 8 bits are sent before. The 32-bit register
occupies two adjacent addresses, the even address stores the lower 16 bits, and the next address (odd
address) of the even address stores the upper 16 bits.
In the register write operation, in order to avoid frequent damage caused by memory EEPROM write,
using the highest bit of the register address indicates whether it save as EEPROM, the highest bit to be 1
indicates to save in EEPROM, 0 means save only in RAM. In other words, if you want to write the
register value which is saved after power-off, you should add 0x8000 to the original register address.
VFD500 register address as follows：
Adress space
0x0000 ~ 0x6363
Name
The function code received by the slave is outside the
configured range
Slave station receives the data address is not allowed
address
the number of registers being Read and write is out of
range
When writing multiple registers, the number of bytes in
the PDU is not equal to the number of registers
Length of frame is not correct
CRC verifying not passed
The data received by the slave exceeds the
corresponding register minimum to maximum range
Operate to read-only register wirte
Operate to read-only register write in running status
High 8 bit means group number (0-99), low 8 bit means within
group serial number (0-99),illustrated by hexadecimal for Example:
Example 1: Function code 06.19, with address is 0x0613 (0x06=6,
0x13=19).Example 2: Function code 27.06, with address is 0x1B06
(0x1B=27, 0x06=6).
Example 3: Function code 40.15, with address is 0x280F
Description
Descriptoin
- 105-
Modbus communication protocol