What am I doing wrong here? You can see the values have the ascii data in the top message but after my function I get no values?
Im trying to just take the ascii values in the buffer or array out of the modbus read and put them into a string so I can pass it to a web service.
Add debug node before the function and show the content of msg. Hard to say something about the mystery object you tried to deal with
Try to use the array spread operator (...) in the function
msg.value = String.fromCharCode(...msg.payload.data)
return msg;
Thank you! That worked in the value field. Now I just need to figure out how to set it to a global variable
That's explained in detail in Node-Red documentation - Storing data
You can store it directly from that function
Should be the other way round if you gonna use a Change node. SET global.SN TO msg.value
No idea 
but you could try to use pop() on that msg.payload.data.pop() that removes the last element from the array. If that character is always there. test it
[EDIT]
let arr = msg.payload.data;
arr.pop();
msg.value = String.fromCharCode(...arr)
return msg;
You are genius! thank you
Nah i just had to research half of the commands on the internet.
But it helps if you do know they exist to look for them.
By the way, test this hackish code with pop() thoroughly so you wont miss a 'legal' character from your SN
For future reference, you might want to try buffer parser node. It takes care of all the byte swapping & conversions & unpacking for you.
Will do. I am removing the windows computer from my control systems so now a linux kernal touchscreen talks modbus to my plc and handles connecting to our IT SOAP services. Sounds like it would be a good idea to put a check on the return data.
The pic 2 works but pic 1 doesnt. I think i am passing too much in the payload. How can I remove the extra portions of the payload?
I didn't understand much of what you have tried in that Change node.
You are trying to embed in a string the global variable SN ?
Use a Function node with the use of template strings.
for Example :
let SN = global.get("SN");
msg.payload = `The Serial Number is ${SN} and it is embedded in a string`
return msg
Note that those are backticks and not single quotes.
I was probably not using it right. Ok, i deleted the unused parts of the msg and got it the same as the pic 2 above but still no go quite yet. See how i dont get that soap envelope back like in pic 2?
Rather than a screenshot of the function paste it here using the </> button at the top of the forum text entry field when pasting it in.
Yea the modbus breaks and the soap so i figured it wasn't very useful to post the code but here it is so far. [{"id":"e6693df7.a3cfa","type":"tab","label":"Flow 4","disabled":false,"info":""},{"id":"eb571ded.e53f3","type":"modbus-read","z":"e6693df7.a3cfa","name":"","topic":"","showStatusActivities":false,"logIOActivities":false,"showErrors":false,"unitid":"1","dataType":"HoldingRegister","adr":"0","quantity":"21","rate":"1","rateUnit":"m","delayOnStart":false,"startDelayTime":"","server":"5410cb45.9afa3c","useIOFile":false,"ioFile":"","useIOForPayload":false,"emptyMsgOnFail":false,"x":110,"y":240,"wires":[[],["bf1abdfc.b1d4e","aafbdb90.305bd8"]]},{"id":"d74a4291.c4218","type":"switch","z":"e6693df7.a3cfa","name":"","property":"payload","propertyType":"msg","rules":[{"t":"eq","v":"1","vt":"num"},{"t":"neq","v":"1","vt":"num"}],"checkall":"false","repair":false,"outputs":2,"x":350,"y":340,"wires":[["2c48206b.b7cbd"],[]]},{"id":"68d47360.93fddc","type":"function","z":"e6693df7.a3cfa","name":"","func":"\nmsg.site = 'AC'\n//msg.serial = msg.payload\nmsg.serial = global.get(\"SN\")\n\n////msg.serial = global.get(\"SN\")\n//msg.serial = 'BVGL01272'\n\n\nvar parse1 = '<?xml version=\"1.0\" encoding=\"utf-8\"?>';\nparse1 = parse1 + '\\n' + '<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">';\n//parse1 = parse1 + '\\n' + ' <soap:Header>';\n//parse1 = parse1 + '\\n' + ' <SoapSettings xmlns=\"http://tempuri.org/\">';\n//parse1 = parse1 + '\\n' + ' <IsTest>false</IsTest>';\n//parse1 = parse1 + '\\n' + ' <ApplicationID>105B9760-A4A0-4659-BE09-2B6F64980DBD</ApplicationID>';\n//parse1 = parse1 + '\\n' + ' <ApplicationKey>C565C1F9-A326-4754-B654-CFA059865820</ApplicationKey>';\n//parse1 = parse1 + '\\n' + ' </SoapSettings>';\n//parse1 = parse1 + '\\n' + ' </soap:Header>';\nparse1 = parse1 + '\\n' + ' <soap:Body>'\nparse1 = parse1 + '\\n' + ' <GetChargeRecipe xmlns=\"http://tempuri.org/\">';\nparse1 = parse1 + '\\n' + ' <serialNumber>' + global.get(\"SN\") + '</serialNumber>';\nparse1 = parse1 + '\\n' + ' <site>' + msg.site + '</site>';\n//parse1 = parse1 + '\\n' + ' <billNum>' + msg.billNum + '</billNum>';\nparse1 = parse1 + '\\n' + ' </GetChargeRecipe>';\nparse1 = parse1 + '\\n' + ' </soap:Body>';\nparse1 = parse1 + '\\n' + '</soap:Envelope>';\nmsg.payload = parse1;\n\ndelete msg.site\ndelete msg.serial\nmsg.topic = \"\";\nreturn msg;\n\n//var testval = global.get(\"test\")||0;\n//msg.payload = testval;\n//return msg;\n\n\n\n\n\n\n\n\n\n\n","outputs":1,"noerr":0,"initialize":"","finalize":"","x":380,"y":260,"wires":[[]]},{"id":"3337f067.a4ca1","type":"simple-soap","z":"e6693df7.a3cfa","host":"http://172.16.17.6:8090/ChargeWs/ChargeService.asmx","hostType":"str","path":"","pathType":"str","action":"http://tempuri.org/GetChargeRecipe","actionType":"str","body":"payload","bodyType":"msg","mustache":false,"attrkey":"$","charkey":"_","stripPrefix":false,"simplify":false,"normalizeTags":false,"normalize":true,"topic":"","name":"","useAuth":false,"x":550,"y":240,"wires":[["bcf8e8a3.96f408","35187516.658fca"]]},{"id":"bf1abdfc.b1d4e","type":"change","z":"e6693df7.a3cfa","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"payload.data[20]","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":200,"y":340,"wires":[["d74a4291.c4218"]]},{"id":"7cad4f22.cfc79","type":"comment","z":"e6693df7.a3cfa","name":"Read from Wago","info":"","x":120,"y":200,"wires":[]},{"id":"37855d95.4f6b3a","type":"comment","z":"e6693df7.a3cfa","name":"Get 20th array position for serial wrote ","info":"","x":150,"y":380,"wires":[]},{"id":"eb4f9416.32b32","type":"comment","z":"e6693df7.a3cfa","name":"Check if equal 1, fire get web service","info":"","x":280,"y":420,"wires":[]},{"id":"77b13775.67d7ac","type":"comment","z":"e6693df7.a3cfa","name":"need SN put back into string global SN","info":"","x":250,"y":100,"wires":[]},{"id":"aafbdb90.305bd8","type":"function","z":"e6693df7.a3cfa","name":"","func":"//msg.value = String.fromCharCode(...msg.payload.data)\n\n//return msg;\nlet arr = msg.payload.data;\narr.pop();\nmsg.value = String.fromCharCode(...arr)\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":180,"y":140,"wires":[["3557e0ae.d936a"]]},{"id":"3557e0ae.d936a","type":"change","z":"e6693df7.a3cfa","name":"","rules":[{"t":"set","p":"SN","pt":"global","to":"value","tot":"msg"}],"action":"","property":"","from":"","to":"","reg":false,"x":330,"y":140,"wires":[[]]},{"id":"6aebd91.ca17728","type":"debug","z":"e6693df7.a3cfa","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":510,"y":300,"wires":[]},{"id":"1182f01a.64e21","type":"comment","z":"e6693df7.a3cfa","name":"Get global SN ","info":"","x":370,"y":220,"wires":[]},{"id":"79d279fa.08fe18","type":"debug","z":"e6693df7.a3cfa","name":"","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":950,"y":280,"wires":[]},{"id":"bcf8e8a3.96f408","type":"function","z":"e6693df7.a3cfa","name":"","func":"\nglobal.set(\"CHARGEPERSYSTEM1\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM1)\nglobal.set(\"CHARGEPERSYSTEM2\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM2)\nglobal.set(\"CHARGEPERSYSTEM3\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM3)\nglobal.set(\"CHARGEPERSYSTEM4\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM4)\nglobal.set(\"CHARGEPERSYSTEM5\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM5)\nglobal.set(\"CHARGEPERSYSTEM6\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM6)\nglobal.set(\"CHARGEPERSYSTEM7\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM7)\nglobal.set(\"CHARGEPERSYSTEM8\",msg.payload[\"soap:Envelope\"][\"soap:Body\"].GetNamePlateInfoBySiteResponse.GetNamePlateInfoBySiteResult[\"diffgr:diffgram\"].DocumentElement.Data.CHARGEPERSYSTEM8)\n\n\nmsg.CHARGEPERSYSTEM1 = global.get(\"CHARGEPERSYSTEM1\");\nmsg.CHARGEPERSYSTEM2 = global.get(\"CHARGEPERSYSTEM2\");\nmsg.CHARGEPERSYSTEM3 = global.get(\"CHARGEPERSYSTEM3\");\nmsg.CHARGEPERSYSTEM4 = global.get(\"CHARGEPERSYSTEM4\");\nmsg.CHARGEPERSYSTEM5 = global.get(\"CHARGEPERSYSTEM5\");\nmsg.CHARGEPERSYSTEM6 = global.get(\"CHARGEPERSYSTEM6\");\nmsg.CHARGEPERSYSTEM7 = global.get(\"CHARGEPERSYSTEM7\");\nmsg.CHARGEPERSYSTEM8 = global.get(\"CHARGEPERSYSTEM8\");\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":820,"y":280,"wires":[["79d279fa.08fe18"]]},{"id":"35187516.658fca","type":"debug","z":"e6693df7.a3cfa","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":730,"y":240,"wires":[]},{"id":"dd225fc6.1380a","type":"change","z":"e6693df7.a3cfa","name":"","rules":[{"t":"set","p":"payload","pt":"msg","to":"<?xml version=\"1.0\" encoding=\"utf-8\"?> <soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"> <soap:Body> <GetChargeRecipe xmlns=\"http://tempuri.org/\"> <serialNumber>' + global.get(\"SN\") + '</serialNumber> <site>AC</site> </GetChargeRecipe> </soap:Body> </soap:Envelope>","tot":"str"},{"t":"set","p":"topic","pt":"msg","to":"","tot":"str"}],"action":"","property":"","from":"","to":"","reg":false,"x":960,"y":520,"wires":[[]]},{"id":"2c48206b.b7cbd","type":"function","z":"e6693df7.a3cfa","name":"","func":"delete msg.values\ndelete msg.input\ndelete msg.sendingNodeId\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":460,"y":580,"wires":[["ab242c2d.571b5"]]},{"id":"ab242c2d.571b5","type":"function","z":"e6693df7.a3cfa","name":"","func":"let SN = global.get(\"SN\");\nmsg.payload = <?xml version=\"1.0\" encoding=\"utf-8\"?> <soap:Envelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/"> soap:Body <GetChargeRecipe xmlns="http://tempuri.org/"> ${SN} AC </soap:Body> </soap:Envelope>\n//msg.topic = \"\";\ndelete msg.topic;\nreturn msg;\n\n","outputs":1,"noerr":0,"initialize":"","finalize":"","x":590,"y":680,"wires":[["3337f067.a4ca1","6aebd91.ca17728"]]},{"id":"5410cb45.9afa3c","type":"modbus-client","z":"","name":"WAGO","clienttype":"tcp","bufferCommands":true,"stateLogEnabled":false,"queueLogEnabled":false,"tcpHost":"localhost","tcpPort":"503","tcpType":"DEFAULT","serialPort":"/dev/ttyUSB","serialType":"RTU-BUFFERD","serialBaudrate":"9600","serialDatabits":"8","serialStopbits":"1","serialParity":"none","serialConnectionDelay":"100","unit_id":"1","commandDelay":"1","clientTimeout":"1000","reconnectOnTimeout":true,"reconnectTimeout":"2000","parallelUnitIdsAllowed":true}]
Edit you post and paste again using
Also what is the global context variable SN showing in the context side bar?
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