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…

@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…

What do you have in the 'optionals' tab?

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?

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?

Node-RED

Node-RED Forum

Raspberry PI connect to RS485

General

mtoko 21 April 2020 13:02 25

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

Topic		Replies	Views
PLC Weidmuller UC20-WL2000-IoT connecting via RS-485 Industrial	15	482	9 May 2023
USB RS485 - RPI4B Connection issue General	3	221	26 July 2023
Debugging - node-red-contrib-modbus - serial RTU General	26	5468	15 February 2021
Modbus RS485 to USB communication Industrial	50	8550	29 May 2020
Modbus RTU using ch340 ttl to usb on pi 4 General modbus	26	644	4 August 2023

Copyright OpenJS Foundation and Node-RED contributors. All rights reserved. The OpenJS Foundation has registered trademarks and uses trademarks. For a list of trademarks of the OpenJS Foundation, please see our Trademark Policy and Trademark List. Trademarks and logos not indicated on the list of OpenJS Foundation trademarks are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.

Raspberry PI connect to RS485

Related topics