INVT Goodrive35 Series User Manual

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Goodrive35 Series Closed-loop Vector Control VFD Communication protocol

221

and if it is even, the check bit is set to "1".

For example, the data bits to be transmitted are "11001110", including five "1". If the even check is

applied, the even check bit is set to "1"; and if the odd check is applied, the odd check bit is set to "0".

During the transmission of the data, the odd/even check bit is calculated and placed in the check bit of

the frame. The receiving device performs the odd/even check after receiving the data. If it finds that

the odd/even parity of the data is inconsistent with the preset information, it determines that a

communication error occurs.

CRC check

A frame in the RTU format includes an error detection domain based on the CRC calculation. The

CRC domain checks all the content of the frame. The CRC domain consists of two bytes, including 16

binary bits. It is calculated by the transmitter and added to the frame. The receiver calculates the CRC

of the received frame, and compares the result with the value in the received CRC domain. If the two

CRC values are not equal to each other, errors occur in the transmission.

During CRC, 0xFFFF is stored first, and then a process is invoked to process a minimum of 6

contiguous bytes in the frame based on the content in the current register. CRC is valid only for the

8-bit data in each character. It is invalid for the start, end, and check bits.

During the generation of the CRC values, the "exclusive or" (XOR) operation is performed on the

each 8-bit character and the content in the register. The result is placed in the bits from the least

significant bit (LSB) to the most significant bit (MSB), and 0 is placed in the MSB. Then, LSB is

detected. If LSB is 1, the XOR operation is performed on the current value in the register and the

preset value. If LSB is 0, no operation is performed. This process is repeated 8 times. After the last bit

bit) is detected and processed, the XOR operation is performed on the next 8-bit byte and the

current content in the register. The final values in the register are the CRC values obtained after

operations are performed on all the bytes in the frame.

The calculation adopts the international standard CRC check rule. You can refer to the related

standard CRC algorithm to compile the CRC calculation program as required.

The following is a simple CRC calculation function for your reference (using the C programming

language):

unsigned int crc_cal_value(unsigned char*data_value,unsigned char data_length)

{

int i;

unsigned int crc_value=0xffff;

while(data_length--)

{

crc_value^=*data_value++;

for(i=0;i<8;i++)

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INVT Goodrive35 Series Specifications

General

Protection Level	IP20
Power Range	0.75kW ~ 630kW
Control Mode	SVC
Overload Capacity	150% for 60 seconds, 180% for 10 seconds
Braking Unit	Built-in or external optional braking unit
Communication Protocol	Modbus
Protection Features	Overvoltage, Undervoltage, Overcurrent, Overload, Overtemperature, Short Circuit, Phase Loss
Ambient Temperature	-10°C to +50°C
Humidity	Less than 95% RH (non-condensing)
Altitude	Below 1000m (derating above 1000m)
Cooling Method	Forced air cooling