Try this flow.
It should get you started.
Change the int32 ‘counter’ to be the analog input for your temperature.
Change the inject from none, to repeat every 12 hours.
(Note, probably should install the FTP node before you import the flow - node-red-contrib-ftp (node) - Node-RED)
Here is what it looks like;
And here is the flow;
[{"id":"7c44525c.f7ae3c","type":"pac-read","z":"6017ee8f.69be8","device":"8edb7df4.9811b","dataType":"int32-variable","tagName":"counter","tableStartIndex":"","tableLength":"","value":"temperature","valueType":"msg","topic":"","topicType":"none","name":"","x":360,"y":120,"wires":[["b549c5e0.528d58"]]},{"id":"84b774cf.dee888","type":"inject","z":"6017ee8f.69be8","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"x":140,"y":120,"wires":[["7c44525c.f7ae3c","4d179918.41c528"]]},{"id":"b549c5e0.528d58","type":"function","z":"6017ee8f.69be8","name":"Date timestamp temperature 'report'","func":"//get the current date and time\nvar d = new Date();\nvar tstring = ('0'+((d.getHours()+11)%12 + 1)).slice(-2)+':';\ntstring += ('0'+d.getMinutes()).slice(-2) + ((d.getHours() >= 12)? 'PM ':'AM ');\ntstring += d.toString().substring(0,4) + d.toISOString().substring(2,10);\n//Append some example text\ntstring += ' Temperature is ';\nmsg.payload = tstring += msg.temperature;\nreturn msg;","outputs":1,"noerr":0,"x":620,"y":120,"wires":[["ea1be5e5.2625e8"]]},{"id":"ea1be5e5.2625e8","type":"file","z":"6017ee8f.69be8","name":"","filename":"/home/dev/temperature.txt","appendNewline":true,"createDir":false,"overwriteFile":"false","x":935.1666870117188,"y":122,"wires":[]},{"id":"4d179918.41c528","type":"delay","z":"6017ee8f.69be8","name":"5 seconds","pauseType":"delay","timeout":"5","timeoutUnits":"seconds","rate":"1","nbRateUnits":"1","rateUnits":"second","randomFirst":"1","randomLast":"5","randomUnits":"seconds","drop":false,"x":373.16668701171875,"y":180,"wires":[["a42c92ea.c35b1"]]},{"id":"a42c92ea.c35b1","type":"ftp in","z":"6017ee8f.69be8","ftp":"a73e9c74.ab82","operation":"put","filename":"temperature.txt","localFilename":"/home/dev/temperature.txt","name":"","x":563.1666870117188,"y":178.6666717529297,"wires":[[]]},{"id":"8edb7df4.9811b","type":"pac-device","z":"","address":"10.192.57.38","protocol":"http"},{"id":"a73e9c74.ab82","type":"ftp","z":"","host":"","port":"","secureOptions":"","user":"","connTimeout":"","pasvTimeout":"","keepalive":""}]