Hi everyone, due to the coronavirus, I have to work at home for my project, which is adapted from my co-worker. One part of the project is interfacing as: Raspberry Pi 3 <-> RS485 Converter <-> speed controllers -> fans We use the RS485 Converter as: [image] On my Pi, I'm using Nodered (Nodejs v…

What do you have in the 'optionals' tab?

link a Modbus response node to the bottom output and set quantity to less than 100 (it is requesting 100 registers)

The datasheet of your controller shows that the status word is at 1001H (hex), so in the modbus node, that would be 4097 decimal. It also shows the status being 5 words in length. I do not know what the data formatting is, if they're using ieee 754 floating point data words, integers divided by some…

optional tab just to show errors and activities. I think for debugging

it does not work, show me the same error. Should i write some command into the register before reading?

Hi @gemini86 , I only changed the quantity to 10 from my previous post. This is the full manual: Manual Cheers

Try reading (function 3) word address 3000, quantity 3.

how did you work out the quantity to be 3?

From the manual you linked. Can't cite the PDF right now, I'm on mobile. Any luck?

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Raspberry PI connect to RS485

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gemini86 21 April 2020 15:12 29

Hey Bond, this could likely be a simple issue, but we need the device manual (the full manual) to be able to help out. What did you change the modbus read node to now?

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Raspberry PI connect to RS485

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