As modbus returns 16bit number, that "first number" is a 16bit (2 byte) number. A float is 32bit (4 bytes) so I presume the manual for your modbus device will give you a formula for converting a 2 byte value into a float.
My guess is you should be reading an int (not UINT) and then probably divide by 10 or 100 or 1000
e.g. - using buffer-parser...
demo flow
[{"id":"7eb013ca918cae85","type":"inject","z":"1683bd9a.5e0a02","name":"faking modbus values","props":[{"p":"payload_as_buffer","v":"[136,37,0,200]","vt":"bin"},{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"[34853, 200]","payloadType":"json","x":2100,"y":540,"wires":[["8df40ef3a7542857"]]},{"id":"8df40ef3a7542857","type":"buffer-parser","z":"1683bd9a.5e0a02","name":"","data":"payload","dataType":"msg","specification":"spec","specificationType":"ui","items":[{"type":"int16be","name":"myFloat_div10","offset":0,"length":1,"offsetbit":0,"scale":"/ 10","mask":""},{"type":"int16be","name":"myFloat_div100","offset":0,"length":1,"offsetbit":0,"scale":"/ 100","mask":""},{"type":"int16be","name":"myFloat_div1000","offset":0,"length":1,"offsetbit":0,"scale":"/ 1000","mask":""},{"type":"int16be","name":"myNumber","offset":2,"length":1,"offsetbit":0,"scale":"1","mask":""}],"swap1":"","swap2":"","swap3":"","swap1Type":"swap","swap2Type":"swap","swap3Type":"swap","msgProperty":"payload","msgPropertyType":"str","resultType":"keyvalue","resultTypeType":"output","multipleResult":false,"fanOutMultipleResult":false,"setTopic":true,"outputs":1,"x":2070,"y":600,"wires":[["16902e50e15dced7"]]},{"id":"16902e50e15dced7","type":"debug","z":"1683bd9a.5e0a02","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":2250,"y":600,"wires":[]}]
alternative version sending multiple messages from one output...
[{"id":"7eb013ca918cae85","type":"inject","z":"1683bd9a.5e0a02","name":"faking modbus values","props":[{"p":"payload_as_buffer","v":"[136,37,0,200]","vt":"bin"},{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"[34853, 200]","payloadType":"json","x":2100,"y":540,"wires":[["8df40ef3a7542857"]]},{"id":"8df40ef3a7542857","type":"buffer-parser","z":"1683bd9a.5e0a02","name":"","data":"payload","dataType":"msg","specification":"spec","specificationType":"ui","items":[{"type":"int16be","name":"myFloat_div10","offset":0,"length":1,"offsetbit":0,"scale":"/ 10","mask":""},{"type":"int16be","name":"myFloat_div100","offset":0,"length":1,"offsetbit":0,"scale":"/ 100","mask":""},{"type":"int16be","name":"myFloat_div1000","offset":0,"length":1,"offsetbit":0,"scale":"/ 1000","mask":""},{"type":"int16be","name":"myNumber","offset":2,"length":1,"offsetbit":0,"scale":"1","mask":""}],"swap1":"","swap2":"","swap3":"","swap1Type":"swap","swap2Type":"swap","swap3Type":"swap","msgProperty":"payload","msgPropertyType":"str","resultType":"value","resultTypeType":"output","multipleResult":true,"fanOutMultipleResult":false,"setTopic":true,"outputs":1,"x":2070,"y":600,"wires":[["16902e50e15dced7"]]},{"id":"16902e50e15dced7","type":"debug","z":"1683bd9a.5e0a02","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":2250,"y":600,"wires":[]}]
Another alternative version - results to own outputs (fan out)
[{"id":"7eb013ca918cae85","type":"inject","z":"1683bd9a.5e0a02","name":"faking modbus values","props":[{"p":"payload_as_buffer","v":"[136,37,0,200]","vt":"bin"},{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"","payload":"[34853, 200]","payloadType":"json","x":2040,"y":540,"wires":[["8df40ef3a7542857"]]},{"id":"8df40ef3a7542857","type":"buffer-parser","z":"1683bd9a.5e0a02","name":"","data":"payload","dataType":"msg","specification":"spec","specificationType":"ui","items":[{"type":"int16be","name":"myFloat_div10","offset":0,"length":1,"offsetbit":0,"scale":"/ 10","mask":""},{"type":"int16be","name":"myFloat_div100","offset":0,"length":1,"offsetbit":0,"scale":"/ 100","mask":""},{"type":"int16be","name":"myFloat_div1000","offset":0,"length":1,"offsetbit":0,"scale":"/ 1000","mask":""},{"type":"int16be","name":"myNumber","offset":2,"length":1,"offsetbit":0,"scale":"1","mask":""}],"swap1":"","swap2":"","swap3":"","swap1Type":"swap","swap2Type":"swap","swap3Type":"swap","msgProperty":"payload","msgPropertyType":"str","resultType":"value","resultTypeType":"output","multipleResult":true,"fanOutMultipleResult":true,"setTopic":true,"outputs":4,"x":2050,"y":640,"wires":[["16902e50e15dced7"],["575a304c4ce43036"],["f23cf12dcee6af06"],["10843da0954e4d4e"]]},{"id":"16902e50e15dced7","type":"debug","z":"1683bd9a.5e0a02","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":2250,"y":580,"wires":[]},{"id":"575a304c4ce43036","type":"debug","z":"1683bd9a.5e0a02","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":2250,"y":620,"wires":[]},{"id":"f23cf12dcee6af06","type":"debug","z":"1683bd9a.5e0a02","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":2250,"y":660,"wires":[]},{"id":"10843da0954e4d4e","type":"debug","z":"1683bd9a.5e0a02","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","statusVal":"","statusType":"auto","x":2250,"y":700,"wires":[]}]
