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…

@Bond This can be frustrating, just some comments Does the python code still work? If it does (or even partially) this would give you some clues. I notice in the python code there is a setting for connection to an MQTT broker, if this code works you could setup a broker in Node Red and communicate …

@mtoko thank you for your comments I have checked out the Modbus scanner. Unfortunately, it cannot be installed on Raspberry PI (or just because i don't know how to). The python code should be working. However the project requirement stated that we do not need to use MQTT, and need to adapt everyt…

I have a lot of experience with using the FTDI rs485 cables to talk to yaskawa ac drives. I like the node-red-contrib-modbus package myself. It's very simple and has a lot of tweakables. In your case, it looks like you should have everything you need in your python file to make this work. The bigge…

@Bond I used the Modbus scanner on a windows computer to get all the communications settings correct (9600, N81) and to ensure that communications with the controller were working including the USB to RS485 converter and confirming modbus registers. With all this working and confirmed it was only n…

Thank you @gemini86 for your response. I think the wiring is correct now because the python can actually run the fans. I think the problem now is just trying to get that python file to work in Nodered. I'm trying to read the status of a working fan (i turned it on physically so it's spinning), but…

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?

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Raspberry PI connect to RS485

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gemini86 21 April 2020 12:56 24

What do you have in the 'optionals' tab?

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Raspberry PI connect to RS485

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