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…

Yes, the Pi is at workplace, and i have to work at home. But that’s not the big deal, via VNC it’s basically the same. I have tried installing RS485 but failed. You can read back to see the error and the whole log that said it cannot be installed. I dont know how to fix that for now. Cheers,

Did you look at the other threads on the forum - is search in RS485? to let you knw I do not have that devide and have never used it jst trying to point you where others have used/tried to use the device.

Of course, I have searched before opening a new topic. I found three libraries above that I may use. But I don't know which one is the best for my project (in terms of effective usage and memory). It kinds of hard for me because I can not see whether the fan is turned on/off (as I'm working from ho…

Bond, first thing we need to know is what is the protocol of speed controllers Modbus (RTU/ASCII) or some simple ASCII/HEX control charters? Can you share a manual? or lin to ? I use a RS485 adapter and use use the standard node-red serial in/out nodes. If your using ASCII control characters it's…

Hi iiLaw, thank you for your response. I'm using a RTU on the speed controllers Modbus. My co-worker did not provide me the manual so i think i have to figure it out. I'm using the adapter too, i did not think the standard node-red serial in/out would work. But as you say so i can try that too.So …

I think the following log tell me that i have installed the modbuscrc: pi@raspberrypi:~/.node-red $ npm i modbuscrc -S npm WARN node-red-project@0.0.1 No repository field. npm WARN node-red-project@0.0.1 No license field. + modbuscrc@1.0.4 added 1 package from 1 contributor and audited 884 package…

A few years ago I posted a flow that works with a Danfoss variable speed drive. I used node-red-contrib-modbus and did take some time but worked well. It is necessary to have detailed information of the modbus registers in the speed controller and the RS485 protocol settings. The flow is posted her…

@Bond I've just tested with A RTU slave simulator. Code could be more concise but it works http://www.simplymodbus.ca/RTUslave.htm [{"id":"e8d88969.351038","type":"debug","z":"a1f9c381.b10a2","name":"read req","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"payload","t…

[image] mtoko: It is necessary to have detailed information of the modbus registers in the speed controller and the RS485 protocol settings. I've used lots of modbus devices over RS-485, and mtoko and iiLaw are correct you will need to know all of the details about the modbus registers as wel…

Raspberry PI connect to RS485

General

iiLaw 9 April 2020 15:02 8

In my case I'm not using RTU but devices that use RS485
That said I can capture RTU msg I use a timeout of 10ms and deliver binary buffers

I have used modcr to play with creating RTU CRC
But you have to install via npm and then refernce it in a function node to use

https://nodered.org/docs/user-guide/writing-functions#global-context

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Raspberry PI connect to RS485

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