Hi, I have problems to convert float and 32b (signed/unsigned) registers to obtain a result able to be sent to MQTT broker. The modbus device is a semaphore/Servelec Tbox unit. I use node-red modbustcp Example: I have a float register with a value of 22.362 in it. I want to pass that value to my M…

In the Change nodes where you extract the individual parts add another row that Sets msg.topic To the/topic/for/this/value

Hi Steve and thank you for the link. It seems that for me the code is not that difficult (...) because values on the array are not hex but plain decimal. With my first test, I put readFloatBE() and I obtained a usable value. However, very strange to me, the result varies with every poll (even the…

I suspect when you update msg.payload in function 1 you are affecting the object before it's processed in the 2nd function. It looks looks like the payload is an array/object so I world probably try returning a new object instead of updating msg.payload e.g... var msg2 = { payload : buf.readFlo…

Can't really help more unless you post your flow and sample data.

[image] Steve-Mcl: I suspect when you update msg.payload in function 1 you are affecting the object before it's processed in the 2nd function. Assuming this is in a recent version of node-red ( @PPz which version is it?) then I don't think that should happen as node-red should automatically cl…

[image] Colin: node.warn() thank you both of you ( @Steve-Mcl ) for your kind help. My version is 1.0.3 the code of the function is : let pay = msg.payload; const buf = Buffer.allocUnsafe(4); // (4) is ok buf.writeUInt16BE(pay[0]); // high byte msg.payload = buf.readFloatBE(0); // 2 numb…

[image] PPz: about node.warn(), I'm affraid that I'm a real newbie about node-red Have you tried searching for it?

[image] Colin: node.warn() Yes, but when I inject node.warn(pay); I receive exactly the same array value [16818,58720] as the raw debug message Update: when I inject node.warn(buf), I obtain a splitted array like this one: [65,178,98,5], or [65,178,125,3], or [65,178,0,0] (variable). Ok, 1…

[image] PPz: let pay = msg.payload; const buf = Buffer.allocUnsafe(4); // (4) is ok buf.writeUInt16BE(pay[0]); // high byte msg.payload = buf.readFloatBE(0); You are allocating a buffer of length 4 bytes. Then you use writeUInt16BE to write to the first two bytes. You have not written an…

[image] Payload's number to two 16 bit register to be send via modbus General Hi ! U can use this code in function....after connect it to Modbus Flex Write function float32ToUint16(value) { var buffer = new ArrayBuffer(4); var intView = new Uint16Array(buffer); v…

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Newbie: convert modbus float [array] register to float value

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Steve-Mcl 14 January 2020 11:22 2

See this thread (read it all) there are some pointers in there that might help.

Topic		Replies	Views
Convert modbus float [array] register to value General	9	13377	28 August 2020
Working between Floating Point and Int. data types General	24	10675	9 April 2020
How to get modbus float from register? General	16	1668	6 September 2020
Modbus TCP float to value General	36	3448	17 April 2022
Modbus UINT16 to decimal? General modbus	35	930	2 October 2023

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Newbie: convert modbus float [array] register to float value

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