Seek the expression of 16crc check code

General
1

Please help:

I use the 16crc check code correctly, but the expression cannot be read by my device. My device needs to express the 4-digit check code separately. Is there any way to achieve it? Thank you
image
I need 03 06 00 0E 00 01 B9 E8 2D C1

Summary

[{"id":"2f11cc20.2f483c","type":"tab","label":"流程 1","disabled":false,"info":""},{"id":"c52abdb8.08d3b8","type":"debug","z":"2f11cc20.2f483c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":590,"y":220,"wires":},{"id":"962cc2bd.4d05d","type":"function","z":"2f11cc20.2f483c","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\nCRCMaster.init();\n\nvar inputType = "HEX";\nvar crcinputcrc16modbus;\nvar crcinput = msg.payload;\nCRCMaster.Calculate(crcinput, inputType);\n\nmsg.payload = crcinput + crcinputcrc16modbus;\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":,"x":380,"y":220,"wires":[["c52abdb8.08d3b8"]]},{"id":"fc0e755b.c6636","type":"inject","z":"2f11cc20.2f483c","name":"03 06 00 0E 00 01 B9 E8 ","props":[{"p":"payload"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"03 06 00 0E 00 01 B9 E8 ","payloadType":"str","x":130,"y":220,"wires":[["962cc2bd.4d05d"]]}]

2

Does the number always come in the same format? The last four digits are always the only problem?

3

Yes.It always displays correctly。

4

You could use a function node with some JavaScript code to insert the space where needed into the string.

5

If I understand correct you only need an extra space between 2D and C1.
If you are sure your hex string is always the same length you can use this in a function node.

msg.payload =msg.payload.substring(0, 26) + " " + msg.payload.substring(26, 28)
return msg;

Are you also sure that the device you have needs a hex string and not an array of bytes?
If the above is not working let us know what type of device your are want to use.

1 Like
6

Thank you. I've just tested your method. It doesn't work. I think my idea should be wrong. My device is TCP to 485 16crc + hex verification 16 bit communication is required

7

Thank you. It works for my project department. My idea is wrong

8

image
image1910×194 60.5 KB

10

My question is, why are you calculating modbus CRC?

Why not simply use the fully working modbus nodes.

11

Just started learning, but I haven't found the tutorial related to using Mobus to connect 485 :fearful:

12

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