CRC16 modbus rtu
Funtion block that adds CRC 16 checksum to modbus rtu command. Example:
input: 010600010100 output: 010600010100D99A
[{"id":"e6126f89.fbab88","type":"tab","label":"modbus rtu crc","disabled":false,"info":""},{"id":"7812b725.54f17","type":"function","z":"e6126f89.fbab88","name":"CRC16-modbus","func":"var CRCMaster = {\n StringToCheck: \"\",\n CleanedString: \"\",\n CRCTableDNP: [],\n init: function() {\n this.CRCDNPInit();\n },\n CleanString: function(inputType) {\n if (inputType == \"ASCII\") {\n this.CleanedString = this.StringToCheck;\n } else {\n if (this.StringToCheck.match(/^[0-9A-F \\t]+$/gi) !== null) {\n this.CleanedString = this._hexStringToString(this.StringToCheck.toUpperCase().replace(/[\\t ]/g, ''));\n } else {\n window.alert(\"String doesn't seem to be a valid Hex input.\");\n return false;\n }\n }\n return true;\n },\n CRCDNPInit: function() {\n var i, j, crc, c;\n for (i = 0; i < 256; i++) {\n crc = 0;\n c = i;\n for (j = 0; j < 8; j++) {\n if ((crc ^ c) & 0x0001) crc = (crc >> 1) ^ 0xA6BC;\n else crc = crc >> 1;\n c = c >> 1;\n }\n this.CRCTableDNP[i] = crc;\n }\n },\n CRC16Modbus: function() {\n var crc = 0xFFFF;\n var str = this.CleanedString;\n for (var pos = 0; pos < str.length; pos++) {\n crc ^= str.charCodeAt(pos);\n for (var i = 8; i !== 0; i--) {\n if ((crc & 0x0001) !== 0) {\n crc >>= 1;\n crc ^= 0xA001;\n } else\n crc >>= 1;\n }\n }\n return crc;\n },\n _stringToBytes: function(str) {\n var ch, st, re = [];\n for (var i = 0; i < str.length; i++) {\n ch = str.charCodeAt(i); // get char\n st = []; // set up \"stack\"\n do {\n st.push(ch & 0xFF); // push byte to stack\n ch = ch >> 8; // shift value down by 1 byte\n }\n while (ch);\n // add stack contents to result\n // done because chars have \"wrong\" endianness\n re = re.concat(st.reverse());\n }\n // return an array of bytes\n return re;\n },\n _hexStringToString: function(inputstr) {\n var hex = inputstr.toString(); //force conversion\n var str = '';\n for (var i = 0; i < hex.length; i += 2)\n str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));\n return str;\n },\n Calculate: function(str, inputType) {\n this.StringToCheck = str;\n if (this.CleanString(inputType)) {\n crcinputcrc16modbus=this.CRC16Modbus().toString(16).toUpperCase();\n crcinputcrc16modbus=crcinputcrc16modbus.substr(2) + crcinputcrc16modbus.substr(0, 2); //swap bytes\n \n }\n }\n};\n\nCRCMaster.init();\n\nvar inputType = \"HEX\";\nvar crcinputcrc16modbus;\nvar crcinput = msg.payload;\n\nCRCMaster.Calculate(crcinput, inputType);\n\nmsg.payload = crcinput + crcinputcrc16modbus;\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":660,"y":380,"wires":[["da260a66.2e0fb"]]},{"id":"265c58e5.dc37a","type":"inject","z":"e6126f89.fbab88","name":"","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"010600010100","payloadType":"str","x":400,"y":380,"wires":[["7812b725.54f17"]]},{"id":"da260a66.2e0fb","type":"debug","z":"e6126f89.fbab88","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":900,"y":380,"wires":[]}]
