CRC algorithm

[matrixmonster11]

I am able to connect to the rfid device ( chafon CF-RU5306 ), I can also send CMDS successfully which already pre-written in demo code ( Nodejs ) , but the issue I am having now is generating the CRC based on Buffer data. Would it be possible to share the also that you worked with please. Here the manual example which I could not replicate in javascript after many tries.
unsigned char CheckSum(unsigned char *uBuff, unsigned short iBuffLen)
{
unsigned char uSum=0;
unsigned short i = 0;
for(i=0;i< iBuffLen;i++)
{
uSum = uSum + uBuff[i];
}
uSum = (~uSum) + 1;
return uSum;
}
Manual reference https://drive.google.com/drive/folders/1GOMv5qGVvhCxKYK_7vSQAX9fz6ssXskk