💬 Building a wired RS485 sensor network

[zrom69]

Hi,
in a node how many children can put rs-485
thanks good work

[zrom69]

and it can have blockages if there are sensors that function or even time
thanks

[dzjr]

@zrom69

I have a node with 52 child id's on a Arduino mega,

Arnout 22 of Them receiving data (relay & dimmers) and the rest are sending data, binary, temp/hum, soil moisture and analog data.

Not all the nodes are in use, but i see the data in domoticz.

I dont know how manny childs you want to use, for me 52 on one node are very mutch.

[zrom69]

thank you for your reply
at least 10 children in node and 30 nodes

[zrom69]

@dzjr
thank you for your reply
at least 10 children in node and 30 nodes
@dzjr

[rafal9318]

Hi all,
I have a question about, How to use hardware serial on Arduino Uno (as a sensor) to communicate with gateway via RS485? I added #define MY_RS485_HWSERIAL Serial and it is only working when i turn on debugging (#define MY_DEBUG), how to use hardware serial without debugger ?

[rejoe2]

@zrom69
No real Problem in turning off debug output, at least in 2.3.1 this worked:

// Enable debug prints to serial monitor
//#define MY_DEBUG
//#define MY_DEBUG_LOCAL

#define SN "Zwischenkeller"
#define SV "0.2"

// Enable RS485 transport layer
#define MY_RS485

// Define this to enables DE-pin management on defined pin
#define MY_RS485_DE_PIN 2

// Set RS485 baud rate to use
#define MY_RS485_BAUD_RATE 19200 //57600 //38400 //9600
#define MY_RS485_SOH_COUNT 1
#define MY_RS485_HWSERIAL Serial
#define MY_SPLASH_SCREEN_DISABLED

You may even swap around debugging output from hardware serial to software serial, see basic structure from this post in FHEM forum (german, but most is code).

[rafal9318]

@rejoe2 Thank you. #define MY_SPLASH_SCREEN_DISABLED that was the missing line.
Okey i understand now. Thank you again.

[Flyer]

I am trying to build up a Mysensors with Wired ethernet to the gateway with W5100 and RS485 bewteen nodes, is there something that can help me with this configuration?
Everything looks weel from the monitor serial but domoticz is not able to connect to the gateway!

[ArduiSens]

@Flyer said in 💬 Building a wired RS485 sensor network:

ng to build

Hi Flyer, As far as I know this is not possible.

[cabat]

@Flyer Do you can ping the gateway on it IP?

[ArduiSens]

I see there is a possibility the combine Ethernet with RS485.
Maybe you can check the setup as they did here:

https://www.openhardware.io/view/649/RS485-Ethernet-Gateway#tabs-comments

https://github.com/feanor-anglin/GetWired-Project/blob/master/GetWired Ethernet Gateway/Gateway.ino

[gryzli133]

You can also try using PJON - it has solved all the issues that I was facing with RS485 and other wired solutions (like all sensors on the Gateway). It will be released officially in MySensors 2.4.0, but you can test is already now (alpha):
https://github.com/tekka007/MySensors

You can read more here:
https://github.com/mysensors/MySensors/pull/1278

[cabat]

@gryzli133 I have a number of MySensors devices using RS485, it would be interesting to try to run PJON protocol over RS485, it seems like there is such an opportunity, but I could not figure out how to use it in the MySensors library.

[hypnosiss]

yes, I am interested too as mysensors sometimes lost messages over rs485.

[cabat]

@hypnosiss you may be interested in this https://forum.mysensors.org/topic/11814/rs485-transport-ack-support/6

[hypnosiss]

@cabat thank you. I have losts when number of messages are sent from HA to nodes(throught mqtt ethernet gateway) and in the same time nodes are sending messages to controller as well. I described issue on Home Assistant forum but without any response - https://community.home-assistant.io/t/lost-messages-sent-simultaneously/363904

[JeeLet]

yes it's not easy, the loss of package is a difficult thing to
to counter, but not entirely.
and the multiple layers of a computer system do not help :)

some philosophy on collision avoidance
https://arduino.stackexchange.com/questions/24523/rs485-multimaster-communication-with-collision-avoidance

don't mix the Protocol (data encapsulation)
and the physical support (voltage frequency impendance / star or serial bus)

the ModBus protocol on a RS485 support
https://www.electroniclinic.com/arduino-modbus-rs485-arduino-rs485-master-and-slave/

a different explanation https://www.codrey.com/learn/rs-485-arduino-quick-primer/

for information
https://github.com/sonyarouje/Arduino_HardwareSerial_RS485

But the best solution (reliability and especially lightness of the sketch) is the CAN bus :)

I may have said some stupid things ;)

Translated with www.DeepL.com/Translator (free version)

[JeeLet]

a line of the examples given in the sketches for the use of RS485 can be a source of problem
(it's my case, I use Pin2 or3 for a long time :( )

...
// Define this to enables DE-pin management on defined pin
#define MY_RS485_DE_PIN 2
(2 or 3 is an interrupt pin for a Uno)
...

avoided interrupt pins.

the pin 10 is a good thing :)

[hypnosiss]

Thank you @JeeLet !
I've been struggling with missing msgs for years with my Arduino Mega
I changed pin and no issues! :D
In the pjon code I've reached to list of tested pins that communication works properly
https://github.com/gioblu/PJON/blob/38e36bb1228c1690143cfbf693a0bcb809514d6c/src/strategies/OverSampling/README.md?plain=1#L12