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The algorithm how to calculate CRC - 16(also known as CRC - 16 / IBM) you will find below.
 
The algorithm how to calculate CRC - 16(also known as CRC - 16 / IBM) you will find below.
   −
var crc = {
+
var crc = {
 
     extractCRC: function (message) {
 
     extractCRC: function (message) {
 
         crcData = message.slice(message.length - 2, message.length);
 
         crcData = message.slice(message.length - 2, message.length);
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         let idx = 0;
 
         let idx = 0;
 
         let crc = 0x0000;
 
         let crc = 0x0000;
 
+
 
         /* the payload length is calculated with removing size of header and CRC (4 + 2 bytes) */
 
         /* the payload length is calculated with removing size of header and CRC (4 + 2 bytes) */
 
         let payload_length = message.length - 6;  
 
         let payload_length = message.length - 6;  
 
+
 
         /* the payload is separated from the message header and CRC (4 bytes ofset + length)*/
 
         /* the payload is separated from the message header and CRC (4 bytes ofset + length)*/
 
         let payload = message.slice(4, 4 + payload_length);
 
         let payload = message.slice(4, 4 + payload_length);
 
+
 
         /* Init value for the first message is zero and for the upcoming messages it is the CRC value of the previous message */
 
         /* Init value for the first message is zero and for the upcoming messages it is the CRC value of the previous message */
 
         crc = previous_crc;
 
         crc = previous_crc;
       
+
 
         for (idx = 0; idx < payload_length; idx++) {
 
         for (idx = 0; idx < payload_length; idx++) {
 
             let bit;
 
             let bit;
   
             /* Use XOR operation for initial value and payload */
 
             /* Use XOR operation for initial value and payload */
 
             crc ^= payload[idx];
 
             crc ^= payload[idx];
 
+
 
             for (bit = 0; bit < 8; bit++) {
 
             for (bit = 0; bit < 8; bit++) {
 
                 let carry_bit = crc & 0x01;
 
                 let carry_bit = crc & 0x01;
 
                 crc >>= 0x01;
 
                 crc >>= 0x01;
 +
 
                 if (carry_bit != 0) {
 
                 if (carry_bit != 0) {
 
                     crc ^= crc_poly;
 
                     crc ^= crc_poly;
 
                 }
 
                 }
 
             }
 
             }
         }
+
         }      
       
   
         return crc;
 
         return crc;
 
     }
 
     }
};
+
};
exports.crc = crc;
+
exports.crc = crc;
    
==File transfer visual flow==
 
==File transfer visual flow==
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