Nextion HMI to D21G

Hi all,

I am in the process of connecting a Nextion 7'' screen to a D21G. If any of you has some insights or code to share, it would be a pleasure to work together on the subject. We are working on an AHU for Operating Rooms in a cardiac surgery hospital, and the Nextion screen would be used as local information as to room temp (value and setpoint setting) and room overpressure (value only).

The RS485 port is used by the Modbus process network, so I plan to use the TTL serial on the expansion port. The screen would not be too close from the controller (say 20 m of cabling from it).

Any information welcome.

Didier, DG2R

| 4 1 3
Asked on 1/31/20, 5:58 AM

Ciao, sono fuori ufficio per motivi di salute, vi risponderò al mio rientro. 


Thank you for your email. I will be out of the office fo health reasons,.I will do my best to respond promptly to your email when I return


on 1/31/20, 5:58 AM

Hi Didier, what a coincidence, i just finished writing a blog post about this:

I have modified the enhanced library to work over RS485. I assume it could work even with Modbus creating some traffic on the RS485, i have not tested that. 

Looking forward to your feedback!

| 1 1 3
Answered on 1/31/20, 6:10 AM

Well ... great minds and all that rot, I guess ! :) I'll have a go at it and let you know. Thanks for saving some of my time (again), Tom ! Didier

on 1/31/20, 6:34 AM

Hello DIdier!

I use Nextion all the time.

It has a serial interface and communicates both ways in text, in terms of variables names and values.

It has a development environment and you program it first, then send and receive text strings.

Very useful, it also has a smart version with RTC, I/O and other stuff.

I usually connect it using two pins and the do a virtual serial, but you might be better off with the Industruino.

At 5 Volts, anyhow.

Il 31 gennaio 2020 alle 7.34 Didier DORGUIN <> ha scritto:

Well ... great minds and all that rot, I guess ! :) I'll have a go at it and let you know. Thanks for saving some of my time (again), Tom ! Didier

Sent by Industruino using Odoo about Forum Post Nextion HMI to D21G (886)
Stefano Giuseppe Bonvini
on 1/31/20, 10:13 PM

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Asked: 1/31/20, 5:58 AM
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Last updated: 1/31/20, 6:10 AM