Ok with your data it is a bit different
i shorten data but should work with longer form
[{"id":"5af14f5a.cd6fe","type":"inject","z":"8d22ae29.7df6d","name":"part 1","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"<?xml version=\"1.0\" encoding=\"UTF-8\"?> <events> <batch name=\"acs.installationtree.update\"> <event id=\"501738\" name=\"acs.door.forcedOpenOff\" type=\"user\" timestamp=\"1606201683114\" operator=\"5\" operatorName=\"master\"> ","payloadType":"str","x":150,"y":1720,"wires":[["74ec2a60.d48064"]]},{"id":"74ec2a60.d48064","type":"function","z":"8d22ae29.7df6d","name":"","func":"let tag = \"event id\" //the tag\nlet splitStart = msg.payload.split(\"<\"+tag);\nif (splitStart.length > 1) {\n if (context.get(\"splitStart\") !== 1){\n msg.payload = \"<\"+tag+splitStart[1];\n context.set(\"splitStart\", 1);\n }else{\n msg.payload = splitStart[0];\n msg.complete = true //send complete msg\n context.set(\"splitStart\", 0);\n }\n}else{\n if (context.get(\"splitStart\") !== 1 ){\n msg.payload =\"\";\n }\n}\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","x":330,"y":1780,"wires":[["3defb2d9.64f5ce"]]},{"id":"3c759e03.8b7e12","type":"inject","z":"8d22ae29.7df6d","name":"part 2","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"nModeAtCommunicationFailure>true</retainMo<dacMode>STANDARD</dacMode><unlockMode>false</unlockMode><buttonEnable>false</buttonEnable><buzzerEnable>false</buzzerEnable><entryReaderBlocked>false</entryReaderBlocked>","payloadType":"str","x":150,"y":1760,"wires":[["74ec2a60.d48064"]]},{"id":"ac7713c3.54d16","type":"inject","z":"8d22ae29.7df6d","name":"part 3","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"<exitReaderBlocked>false</exitReaderBlocked><entryReaderDoorCode>false</entryReaderDoorCode><exitReaderDoorCode>false</exitReaderDoorCode><entryReaderSystemCard>false</entryReaderSystemCard><exitReaderSystemCard>false</exitReaderSystemCard><retainRelayStatus>false</retainRelayStatus><forceOpen>true</forceOpen><forceClose>false</forceClose><hio>false</hio></dac>]]></argument></event><event id=\"487230\" name=\"acs.door.forcedBlockOff\" type=\"user\" timestamp=\"1605790218343\" operator=\"5\" operatorName=\"master\"><argument value=\"Lindaaaaahl\" type=\"dac\" id=\"26\" externalId=\"ID:26_20181220_130306\"/>","payloadType":"str","x":150,"y":1800,"wires":[["74ec2a60.d48064"]]},{"id":"3defb2d9.64f5ce","type":"join","z":"8d22ae29.7df6d","name":"","mode":"custom","build":"string","property":"payload","propertyType":"msg","key":"topic","joiner":"","joinerType":"str","accumulate":false,"timeout":"","count":"","reduceRight":false,"reduceExp":"","reduceInit":"","reduceInitType":"","reduceFixup":"","x":510,"y":1800,"wires":[["2da22367.b6999c"]]},{"id":"2da22367.b6999c","type":"debug","z":"8d22ae29.7df6d","name":"","active":true,"tosidebar":true,"console":false,"tostatus":true,"complete":"payload","targetType":"msg","statusVal":"$substring(payload, 0, 11) & $substring(payload,-11)","statusType":"jsonata","x":710,"y":1800,"wires":[]}]