💬 Building a wired RS485 sensor network

  • @Reza
    I recommend nothing solder or unsolder now.
    Simply start with two Arduinos on two ends of cable.
    When your communication will work for these two devices, then you can go further.
    For one Arduino write simple sketch, which will periodically send something ("Hello World/n" )
    to the bus. Other Arduino with sketch witch will receive characters and sends then through USB serial port to serial monitor on PC. Only with AltSoftSerial library, not with MySensors.
    When this communication will work on any length of cable ( I suppose you have not cable longer then 1km at your home ), you can go further.
    You do not need drive DE and RE pins by software, simply on transmitting Arduino set it for transmit ( to +5V ) and on receiving Arduino to ground.

  • @kimot this hard for me because i am beginner 🙂 but thank you very thank you for help 🙏 🙏 🙏

  • Hardware Contributor

    Hi, i have a Gateway running and the motion-sensor. The Sensors talks with the Gateway. (Arduino Pins: D2,D8,D9)
    Now i have to switch to another Hardware. On the Arduino-Pro Mini i have easy access to 0-RX, 1-TX, 2-D5, 3-D5, 4-D7, 10-13, A1-A3)
    Which combination of this pins would be the best, and how can i define it in the sketch ?
    Im happe for each hint.

  • The 510 ohm pull up and pull down resistors are usually mounted on the master side. Theoretically it
    would be best to install it in the middle of your bus line. The 120 ohm termination resistor must always
    be used on distances greater than 1 meter and/or baud rates higher than 9600. It’s best to install it as a
    norm as noise and reflections will cause havoc on your communication once implemented in the field.
    The termination resistors should be mounted at both ends of the bus line. Please note that adding bias
    resistors will load the driver IC output. With the indicated values the max number of units on the bus
    line is limited to eight 12kΩ, sixteen 24kΩ, or thirty-two 48kΩ units.
    For further protection transient suppressors can be installed across the differential lines, from the Vcc to
    D+ and from GND to D-.!

  • Google for simple Modbus Master dcouments (arduino forum)

    The MAX485 is not the best RS485 chip because of it's own internal impedance.
    The chip in the diagram can be change by MAX485, MAX...


  • FYI

  • Hi, I'm building my home automation system and I have UTP cables cat5e in walls going to my wall switches. I have four cables, 5 nodes on one cable, 2 nodes on the second cable, and one node on 3rd and one 4th cable. 9 nodes. I know that the RS485 should be connected in parallel on single twisted pair but i cant change cables now cause my walls are painted etc.. So I have few problems, nodes stops working, i need to reset them few times, after few days the network stops to work and i start to search for an answers here. I changed numbers of SOH from 1 to 3 in 274 line of MyTransportRS485.cpp and now I think the network working better. I have 120ohm resistor in every node. You think that I should remove them ? Nodes are max 10 meters from the gateway so the cable lengths aren't so long.

  • @nofox
    If you have got one free pair of wires in cat5e cable, it is easy to convert your "star" topology to pure 485 bus topology with terminal resistors on both ends only.

  • Mod

    I think the 120Ohms resistor needs to go at the end of the cable, not on each node

  • @kimot I was thinking about that before I wrote here, and if nothing else can help I will convert star to bus.

  • @nofox it's what gohan stated, the 120ohm resistors should only put on the first and last node of you network. And you can only use a "bus" network topology for RS485.You should use the other wires of you Ethernet cable to accomplish this like kimot wrote.

  • Ok, so i switched my RS485 network to "bus". I desolder all of 120ohm resistors and have them only on both ends of the bus. RS485 to Ethernet gateway is in the middle of the wire. There are still some problems.. When I switching on the power and reading debug from gate I see that only 4 from 9 nodes are presenting. I need to reset other nodes manually to get them properly presented to the gateway. What am I doing wrong ? I need help I think.. Maybe its caused by the fact that all nodes powering on at the same time and there are many collisions on the RS485 bus ?? Maybe I should add some different delay() to setup part of my sketches to give, a time for every single node to present to the gateway ? Someone have successful working rs485 mysensors network here ?

    This is code for one of my nodes with buttons, relays and temperature sensor:

    #define MY_NODE_ID 8
    // Enable debug prints to serial monitor
    #define MY_DEBUG 
    // 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 9600
    #include <SPI.h>
    #include <MySensors.h>
    #include <Bounce2.h>
    #include <DallasTemperature.h>
    #include <OneWire.h>
    #include <OneButton.h>
    // define actions for OneButton function
    typedef enum {
      ACTION_OFF_1,  // set relay "OFF".
      ACTION_ON_1,   // set relay "ON"
    MyActions nextAction_1 = ACTION_OFF_1;
    MyActions nextAction_2 = ACTION_OFF_2;
    // define Arduino I/O pins for relays
    #define RELAY_1  3 // Arduino Digital I/O pin number for first relay
    #define RELAY_2  5 // Arduino Digital I/O pin number for first relay
    #define RELAY_ON 1  // GPIO value to write to turn on attached relay
    #define RELAY_OFF 0 // GPIO value to write to turn off attached relay
    // configure parameters for 1Wire temp sensor
    #define COMPARE_TEMP 1
    #define ONE_WIRE_BUS 6
    #define MAX_ATTACHED_DS18B20 16
    // define CHILD IDs for relays and virtual multiaction click/doubleclick/longpress buttons
    #define CHILD_ID_11 11 // child id for first relay and first button single click 
    #define CHILD_ID_12 12 // child id for second relay and second button single click
    // #define CHILD_ID_13 13 // child id for first button single click (in this version not active because single click is attached directly to relay state)
    #define CHILD_ID_14 14 // child id for first button double click
    #define CHILD_ID_15 15 // child id for first button long press
    // #define CHILD_ID_16 16 // child id for second button single click (in this version not active because single click is attached directly to relay state)
    #define CHILD_ID_17 17 // child id for second button double click
    #define CHILD_ID_18 18 // child id for second button long press
    // define variables for temperature (and other) 1Wire Sensors
    long previousMillis = 0;
    long sensorInterval = 60000; // interval for temperature measurement 
    long HI_interval = 1000;
    OneWire oneWire(ONE_WIRE_BUS);
    DallasTemperature sensors(&oneWire);
    float lastTemperature[MAX_ATTACHED_DS18B20];
    int numSensors=0;
    bool recivedConfig = false;
    bool metric = true;
    // define Arduino Digital I/O pins for OneButton function
    OneButton BUTTON_1(7, true); // Arduino Digital I/O pin number for first physical button
    OneButton BUTTON_2(10, true); // Arduino Digital I/O pin number for second physical button
    bool V1_BUTTON_1; // set variable for virtual one click button 1
    bool V2_BUTTON_1; // set variable for virtual double click button 1
    bool V3_BUTTON_1; // set variable for virtual long press button 1
    bool V1_BUTTON_2; // set variable for virtual one click button 2
    bool V2_BUTTON_2; // set variable for virtual one click button 2
    bool V3_BUTTON_2; // set variable for virtual one click button 2
    bool state1; // variable for RELAY_1 states 
    bool state2; // variable for RELAY_2 states 
    void before()
    //define messages for diferent type of sensors CHILD_IDs used
    MyMessage msg0(0,V_TEMP); // temperature sensor message
    MyMessage msg11(CHILD_ID_11, V_LIGHT); // first relay & single click message
    MyMessage msg12(CHILD_ID_12, V_LIGHT); // second relay & single click message
    // MyMessage msg13(CHILD_ID_13, V_LIGHT); // button 1 Single click
    MyMessage msg14(CHILD_ID_14, V_LIGHT); // button 1 Double click
    MyMessage msg15(CHILD_ID_15, V_LIGHT); // button 1 Long press
    // MyMessage msg16(CHILD_ID_16, V_LIGHT); // button 2 Single click
    MyMessage msg17(CHILD_ID_17, V_LIGHT); // button 2 Dobule click
    MyMessage msg18(CHILD_ID_18, V_LIGHT); // button 2 Long press
    void setup()
    digitalWrite(RELAY_1, RELAY_OFF); // Set first relay state and pin mode
     pinMode(RELAY_1, OUTPUT);
    state1 = loadState(CHILD_ID_11);  // Set relay to last known state (using eeprom storage)
     digitalWrite(RELAY_1, state1?RELAY_ON:RELAY_OFF);
    digitalWrite(RELAY_2, RELAY_OFF); // Set second relay state and pin mode 
     pinMode(RELAY_2, OUTPUT);
    state2 = loadState(CHILD_ID_12);  // Set relay to last known state (using eeprom storage)
     digitalWrite(RELAY_2, state2?RELAY_ON:RELAY_OFF); 
    // sending states of relays after node bootup
    // attaching physical BUTTON_1 to OneButton function actions
    // attaching physical BUTTON_2 to OneButton function actions
    // setup for temperature sensor
    void presentation()
        sendSketchInfo("pokoiczek_puszka_1", "1.0");
        numSensors = sensors.getDeviceCount();
      // Present all sensors to controller
      for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {   
         present(i, S_TEMP);
        present(CHILD_ID_11, S_LIGHT);
        present(CHILD_ID_12, S_LIGHT);
        // present(CHILD_ID_13, S_LIGHT);
        present(CHILD_ID_14, S_LIGHT);
        present(CHILD_ID_15, S_LIGHT);
        // present(CHILD_ID_16, S_LIGHT);
        present(CHILD_ID_17, S_LIGHT);
        present(CHILD_ID_18, S_LIGHT);
    void loop()
      temperatureCheck(); // tmperature check function
      // states for nextAction of OneButton function
      if(state1 == HIGH)
          nextAction_1 = ACTION_OFF_1;
          nextAction_1 = ACTION_ON_1;
      BUTTON_1.tick();  // reading state of first physical button 
      if(state2 == HIGH)
          nextAction_2 = ACTION_OFF_2;
          nextAction_2 = ACTION_ON_2;
      BUTTON_2.tick(); // // reading state of second physical button 
    void singleclick_BUTTON_1()
      if (nextAction_1 == ACTION_OFF_1 )
          nextAction_1 = ACTION_ON_1;
          send(msg11.set(HIGH?false:true), true);
        nextAction_1 = ACTION_OFF_1;
        send(msg11.set(LOW?false:true), true);
      // send(msg13.set(LOW ? 1 : 0));
      // send(msg13.set(HIGH ? 1 : 0));
    void doubleclick_BUTTON_1()
       send(msg14.set(LOW ? 1 : 0));
       send(msg14.set(HIGH ? 1 : 0));
    void longpress_BUTTON_1()
       send(msg15.set(LOW ? 1 : 0));
       send(msg15.set(HIGH ? 1 : 0));
    void singleclick_BUTTON_2()
       if (nextAction_2 == ACTION_OFF_2 )
          nextAction_2 = ACTION_ON_2;
          send(msg12.set(HIGH?false:true), true);
        nextAction_2 = ACTION_OFF_2;
        send(msg12.set(LOW?false:true), true);
      // send(msg16.set(LOW ? 1 : 0));
      // send(msg16.set(HIGH ? 1 : 0));
    void doubleclick_BUTTON_2()
       send(msg17.set(LOW ? 1 : 0));
       send(msg17.set(HIGH ? 1 : 0));
    void longpress_BUTTON_2()
       send(msg18.set(LOW ? 1 : 0));
       send(msg18.set(HIGH ? 1 : 0));
    void temperatureCheck()
     unsigned long currentMillis = millis();
     if(currentMillis - previousMillis > sensorInterval)
        previousMillis = currentMillis;
      // Fetch temperatures from Dallas sensors
      // query conversion time and sleep until conversion completed
      int16_t conversionTime = sensors.millisToWaitForConversion(sensors.getResolution());
      // sleep() call can be replaced by wait() call if node need to process incoming messages (or if node is repeater)
      // Read temperatures and send them to controller 
      for (int i=0; i<numSensors && i<MAX_ATTACHED_DS18B20; i++) {
        // Fetch and round temperature to one decimal
        float temperature = static_cast<float>(static_cast<int>((getControllerConfig().isMetric?sensors.getTempCByIndex(i):sensors.getTempFByIndex(i)) * 10.)) / 10.;
        // Only send data if temperature has changed and no error
        #if COMPARE_TEMP == 1
        if (lastTemperature[i] != temperature && temperature != -127.00 && temperature != 85.00) {
        if (temperature != -127.00 && temperature != 85.00) {
          // Send in the new temperature
          // Save new temperatures for next compare
    void receive(const MyMessage &message)
      if (message.type == V_STATUS && message.sensor == 11) {
        // Change relay state
        state1 = message.getBool();
        digitalWrite(RELAY_1, state1?RELAY_ON:RELAY_OFF);
        // Store state in eeprom
        saveState(CHILD_ID_11, state1);
       // send(msg11.set(state1));
         // Write some debug info
        Serial.print("Incoming change for sensor:");
        Serial.print(", New status: ");
      else if (message.type == V_STATUS && message.sensor == 12) {
        state2 = message.getBool();
        digitalWrite(RELAY_2, state2?RELAY_ON:RELAY_OFF);
        saveState(CHILD_ID_12, state2);
       // send(msg12.set(state2));
        // Write some debug info
        Serial.print("Incoming change for sensor:");
        Serial.print(", New status: ");

    I'm using OneButton library to get different actions when i'm clicking once, twice and holding buttons.

  • Nofox,

    1. The 510 ohm pull up and pull down resistors (between A (D+) and 5V / between B (D-) and ground) are usually mounted on the master side (which is your gateway). Theoretically it would be best to install it in the middle of your bus line.
    2. check if your power supply has enough power to feed all your nodes
    3. check that all the ground lines of your boards are connected with each other.

  • @ArduiSens Thanks for your reply! I have found few post here on MYS Forum about biasing rs485 line with pull up and pull down resistors and I will try to do this tomorrow. I'm using standard rs485 module from aliexpress on the gateway side. There are pullups and pulldowns there but they are two 10k resistors, I will change them to 510 as you mentioned.
    All of my wired sensors, gateway and RPi are powered form 10A buffered power supply. I've checked voltage on every node. I have 5.25V on power supply pins in the middle of the line and 5.21 on both ends of line. I'm using one twisted pair for Vcc and one for GND. The bus is about 15 meter long form one end to another.
    As I mentioned above all of nodes are supplied from one power supply so the grounds are all connected.

  • Hello again. I've soldered this two pull-ups resistors like @ArduiSens wrote before. Now I think the network works much much better but after 24 hours of using something hangs and i can't turn of the light with buttons and with OpenHab also. I think the gateway freezing because after I reset only gateway all starts to work normal when i'm pressing wall switches. I need to reboot controller because after gateway reset OpenHab won't communicate with the gateway... Please take a look at my gateway sketch:

    // Enable debug prints to serial monitor
    #define MY_DEBUG
    // Enable and select radio type attached
    // #define MY_RADIO_NRF24
    // #define MY_RADIO_RFM69
    #define MY_NODE_ID 0
    // 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 9600
    // Enable gateway ethernet module type
    #define MY_GATEWAY_W5100
    // W5100 Ethernet module SPI enable (optional if using a shield/module that manages SPI_EN signal)
    // #define MY_W5100_SPI_EN 4
    // Enable Soft SPI for NRF radio (note different radio wiring is required)
    // The W5100 ethernet module seems to have a hard time co-operate with
    // radio on the same spi bus.
    #if !defined(MY_W5100_SPI_EN) && !defined(ARDUINO_ARCH_SAMD)
    #define MY_SOFTSPI
    #define MY_SOFT_SPI_SCK_PIN 14
    #define MY_SOFT_SPI_MISO_PIN 16
    #define MY_SOFT_SPI_MOSI_PIN 15
    // When W5100 is connected we have to move CE/CSN pins for NRF radio
    // #ifndef MY_RF24_CE_PIN
    // #define MY_RF24_CE_PIN 5
    // #endif
    // #ifndef MY_RF24_CS_PIN
    // #define MY_RF24_CS_PIN 6
    // #endif
    // Enable to UDP
    // #define MY_USE_UDP
    #define MY_IP_ADDRESS 192,168,0,66   // If this is disabled, DHCP is used to retrieve address
    // Renewal period if using DHCP
    //#define MY_IP_RENEWAL_INTERVAL 60000
    // The port to keep open on node server mode / or port to contact in client mode
    #define MY_PORT 5003
    // Controller ip address. Enables client mode (default is "server" mode).
    // Also enable this if MY_USE_UDP is used and you want sensor data sent somewhere.
    //#define MY_CONTROLLER_IP_ADDRESS 192, 168, 0, 70
    // The MAC address can be anything you want but should be unique on your network.
    // Newer boards have a MAC address printed on the underside of the PCB, which you can (optionally) use.
    // Note that most of the Ardunio examples use  "DEAD BEEF FEED" for the MAC address.
    #define MY_MAC_ADDRESS 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
    // Set this node's subscribe and publish topic prefix
    // #define MY_MQTT_PUBLISH_TOPIC_PREFIX "mygateway1-out"
    // #define MY_MQTT_SUBSCRIBE_TOPIC_PREFIX "mygateway1-in"
    // Set MQTT client id
    // #define MY_MQTT_CLIENT_ID "mysensors-1"
    // Enable these if your MQTT broker requires usenrame/password
    //#define MY_MQTT_USER "username"
    //#define MY_MQTT_PASSWORD "password"
    // Enable inclusion mode
    // Enable Inclusion mode button on gateway
    // Set inclusion mode duration (in seconds)
    // Digital pin used for inclusion mode button
    // Set blinking period
    // Flash leds on rx/tx/err
    // Uncomment to override default HW configurations
    //#define MY_DEFAULT_ERR_LED_PIN 7  // Error led pin
    //#define MY_DEFAULT_RX_LED_PIN  8  // Receive led pin
    //#define MY_DEFAULT_TX_LED_PIN  9  // Transmit led pin
    #if defined(MY_USE_UDP)
    #include <EthernetUdp.h>
    #include <Ethernet.h>
    #include <MySensors.h>
    void setup()
    void loop()

  • Mod

    @nofox why are you using soft SPI? You don't have a nrf24 radio

  • @gohan I'm using soft SPI ? Where ? I taught that there are

    #if !defined(MY_W5100_SPI_EN) && !defined(ARDUINO_ARCH_SAMD)
    #define MY_SOFTSPI
    #define MY_SOFT_SPI_SCK_PIN 14
    #define MY_SOFT_SPI_MISO_PIN 16
    #define MY_SOFT_SPI_MOSI_PIN 15

    so when #define MY_W5100_SPI_EN 4 is commented I'm using hardware SPI ? What should i change than ? Comment the whole #if .... part ??

  • Mod

    Forget it, I was on mobile and couldn't see well the code. Do you have IDE, boards definitions up to date? Did you try latest version of mysensors in development branch?

  • @gohan I have IDE 1.6.11 and boards definition 1.6.11 because on newer boards definition I've got boot loop on gateway. I'm using 2.1.1 MySensors library. Maybe I should mention that I can ping my gateway without any problems, only rs485 part seems not responding..

  • Hello again. After a week of thinking and hard work i finally got RS485 network working very close to what I want. I've done everything like it was mentioned here before. Fully bus-like network, termination only on both ends of line and pull-up and pull-down on the gateway. I also change MySensors library to newest 2.1 beta branch. All nodes working very good for last month but some times one node hanging and I can't control it via OpenHab or built in switch. I don't know what cause this behavior. I turn on watchdog timers in every nodes and theoretically when node hangs, watchdog should reboot arduino after 8 seconds. Practically it won't reboot my node.. It seems like the node don't really hangs but the communication stops.. Is it possible that one node can loose connection while other nodes on the same bus/wires working like a charm ?

  • @nofox The problem you describe sounds pretty similar to my observations in this post.
    There are also some suggestions how to solve this kind of trouble you may apply.

  • Hi! It’s me again. I want to precise one thing. Are there anyone here who have succesful working RS485 network without any issues? We are talking here about issues but maybe someone have fully working sensors network?

  • If some node hangs what happens if you recycle the power of rs485 transceiver only?
    I'm just thinking could it be the protection of max485 that kicks in if there is two nodes sending exactly the same time.

  • Hi! My problem still exist. I switched to newest MySensors Library and to HWSERIAL and some nodes acts the same as before... Now i'm thinking that maybe its related to DE_PIN 2 ?? Someone tried to switch to other pin for Enable function for RS485 ?? Now after almost a year I'm thinking about changing my transmission from wired RS485 to wireless nRF.. I choose RS485 because of its stability (thats what I taught over a year ago ). Now I think that RS485 its a piece of garbage..

  • Hi! I think I came up with the solution for all our problems but I don't know if it is worth and possible at all. The thing is that RS485 isn't a multimaster bus, thats what we all know. So the best option is to turn the gateway in to master and all other nodes to slaves. I'm thinking if there are any possibilities to make the gateway to ask nodes in the order one by one for its states (child states). The nodes can only talk to the gateway when the gateway ask for their states. This process should take place in endless loop in the highest possible speed (depending on the count of nodes in the network). I think that in this option the baud rate matters, cause higher baud rates makes the time of a single loop shorter minimizing the delay that may occur in the networks with many nodes. Maybe I'm reinventing the wheel now and this type of transmission needs to rewrite all MySensors protocols..

  • @nofox absolutely that is one of the problems. Polling as you describe could be a fix, another is having each node listen before transmitting, there is a (not mysensors) library that does that, CAN bus( a mutli master 485 comaptible bus) is another option. I think that running a common ground to all the rs485 adapters is also wise. This is all in theory as I havent wired up my home yet....

  • @wallyllama

    another is having each node listen before transmitting

    How would you describe this functionality in MySensors rs485 code?
    If I'm reading the code correctly it is exactly reading the bus and making sure no other node is sending before sending anything.
    The place where collision can happen is those 5 microseconds what the node is waiting to get driver tx enabled pin up.

    So the collision avoidance is already there. So what MyS R485 transport is missing is collision detection and recovery from collision.

    CAN bus( a mutli master 485 comaptible bus) is another option.

    Its disadvantage is small payload size.

    @nofox Its quite like how the Modbus works. By polling.
    I think there is some better ways to do that. Check these out from google:

    • RS-485 Token ring
    • uLAN
    • RS-485 RRP (Round Robin Protocol)
    • CSMA/CA

  • I think you have found most everything that I have. Something akin to csmacd is what I was thinking. Listen, transmit, back off for random time if a collision still happens. Of course full duplex rs485 is another option, hard to find off the shelf modules.

    I think this is the library I had found before.

  • https://github.com/dukelec/cdbus_doc
    This one has some is interesting, not sure if it does multi master or not. There are a few projects that seem to do multimaster/collision avoidance, the trick it to find one with low enough overhead and automatically retransmits if there is a failure, and for this project isolates this enough that my sensors doesnt need restructuring.

    Good wiring is crucial so you can use higher speeds. The common ground wire in addition to the differential signals seems almost required.

  • But PJON uses completely sw bit by bit sending or HW sending with bad bus arbitration.

    My idea - combination CAN bus like arbitration and UART message sending.
    With ACK possibility.

    Time T1 ( two bytes send time for example )

    Node sends message and waits T1 time for ACK.
    Receiving node must send ACK within T1 interval.

    Node, witch needs send message listens bus.
    BUT not by HW UART or SoftwareSerial - use directo IO operation.
    If recognize bus free time greater then T1, it start sending its own ID.
    BUT again not by HW UART or SoftwareSerial - but bit by bit by direct IO pin operation.
    And listen if bit I am sending is bit I am receiving.
    If not - it means, that other node with higher priority ( lower ID ) is sending - then immediately stop sending other bit and wait for next bus free T1 interval.
    If yes - bus is free for me end send my message normally by UART ( HW or SW, maybe with 9 bit addressing support - time less than T1 between characters allowed).
    Wait max T1 time for ACK.

    CAN bus driver usage TJA 1050 or MCP2551 - no DE RE pins.

  • I have the problem that I always get this error: !TSM:FPAR:NO REPLY

    Once it worked briefly yesterday.

    What have I tried everything?
    All hardware exchanged - without success.

    Now I have just written two small scripts that send RS485 back and forth. without problems. So wiring has to fit. I spent then in the serial montior the data which the node sends me, there comes some. Then I once tried to display the data that sends the GW, because nothing comes.

    Does anyone have an idea why my GW does not answer?

  • Mod

    @andreas-sieber could you post the debug output from the node and the gateway?

  • | / |_ / | ___ _ __ ___ ___ _ __ ___
    | |/| | | | _
    \ / _ \ _ \/ __|/ _ \|
    _/ __|
    | | | | |
    | || | / | | _ \ _ | | _
    | |
    , |/ ___|| ||/_/|| |/
    __/ 2.3.0-alpha

    17 MCO:BGN:INIT NODE,CP=RSNNA---,VER=2.3.0-alpha
    26 TSM:INIT
    27 TSF:WUR:MS=0
    30 TSM:FPAR
    49 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    2058 TSM:FPAR
    2075 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    4085 TSM:FPAR
    4103 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    6113 TSM:FPAR
    6130 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:

    0;255;3;0;9;0 MCO:BG
    0;255;3;0;9;29 MCO:BGN:INIT OK,TSP=1
    0;255;3;0;9;0 MCO:BGN:INIT GW,CP=RSNGA---,VER=2.3.0-alpha
    0;255;3;0;9;5 TSM:INIT
    0;255;3;0;9;7 TSF:WUR:MS=0
    0;255;3;0;9;9 TSM:INIT:TSP OK
    0;255;3;0;9;12 TSM:INIT:GW MODE
    0;255;3;0;9;15 TSM:READY:ID=0,PAR=0,DIS=0
    0;255;3;0;9;18 MCO:REG:NOT NEEDED
    0;255;3;0;14;Gateway startup complete.
    0;255;3;0;9;22 MCO:BGN:STP
    0;255;3;0;9;29 MCO:BGN:INIT OK,TSP=1

  • Mod

    why don't you use the stable 2.2? Anyway the node is missing the my_node_id define and second it seems the gateway isn't receiving anything, so I guess there is something very wrong in communication

  • in the 2.2 the same problem, i have now updagradet to alpha.

    When you have a solution on 2.2 i will downgrade. no problem!

    Guys you are good! I had set the mynodeid. But befor i include the my sensors.. that's the mistake..

    hour of hour to search... thx!

  • Is it possible, or will it be possible to build a combination between wired and wireless nodes?

  • Mod

    one network, one gateway

  • I just trying to work with examples but my node always transmitting some piece of shit from hardware serial:

     __  __       ____
    |  \/  |_   _/ ___|  ___ _ __  ___  ___  _ __ ___
    | |\/| | | | \___ \ / _ \ `_ \/ __|/ _ \| `__/ __|
    | |  | | |_| |___| |  __/ | | \__ \  _  | |  \__ \
    |_|  |_|\__, |____/ \___|_| |_|___/\___/|_|  |___/
            |___/                      2.3.0
    25 TSM:INIT
    26 TSF:WUR:MS=0
    29 TSF:SID:OK,ID=5
    31 TSM:FPAR
    ⸮X⸮⸮w34 TSF:MSG:SEND,5-5-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    2043 TSM:FPAR
    ⸮X⸮⸮w2045 TSF:MSG:SEND,5-5-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    4056 TSM:FPAR
    ⸮X⸮⸮w4058 TSF:MSG:SEND,5-5-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    6068 TSM:FPAR
    ⸮X⸮⸮w6070 TSF:MSG:SEND,5-5-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    8078 !TSM:FPAR:FAIL
    8079 TSM:FAIL:CNT=1
    8081 TSM:FAIL:DIS
    8083 TSF:TDI:TSL

    From software serial too


    Consequently the gateway can't find any device.
    I have tried also with RS485 with different baudrate. Finally I just connect my USB TTL directly to ouput pins, but always same result.
    How to fix it?

  • @Pavel-Polititsky
    To me this looks like you mixed between-node communication (RS485) with debug output (and maybe also serial output of the gw).
    The corresponding serial interface for RS485 should be dedicated to RS485 exclusively.

  • Hi,
    first of I have to thank you for your effort on this project! It helped me a lot.
    In my house I would like to build 2 networks, one with serial gateway with RF24 for ground floor and outside. Second will be in cellar and I was thinking about Ethernet gateway (W5500) but sensors will be connected via RS485. Do you have code for that? On the video it looks like that in the box on right side it is something like this.

  • I have exactly the same problem. Has anyone managed to run it.

  • | / |_ / | ___ _ __ ___ ___ _ __ ___
    | |/| | | | _
    \ / _ \ _ \/ __|/ _ \|
    _/ __|
    | | | | |
    | || | / | | _ \ _ | | _
    | |
    , |/ ___|| ||/_/|| |/
    __/ 2.3.1

    16 MCO:BGN:INIT NODE,CP=RSNNA---,REL=255,VER=2.3.1
    26 TSM:INIT
    27 TSF:WUR:MS=0
    30 TSM:FPAR
    56 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    2065 TSM:FPAR
    2082 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    4092 TSM:FPAR
    4110 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    6120 TSM:FPAR
    6137 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    8146 !TSM:FPAR:FAIL
    8147 TSM:FAIL:CNT=1
    8150 TSM:FAIL:DIS
    8152 TSF:TDI:TSL
    18154 TSM:FAIL:RE-INIT
    18156 TSM:INIT
    18157 TSM:INIT:TSP OK
    18159 TSM:FPAR
    18178 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    20186 !TSM:FPAR:NO REPLY
    20188 TSM:FPAR
    20206 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    22213 !TSM:FPAR:NO REPLY
    22215 TSM:FPAR
    22234 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    24241 !TSM:FPAR:NO REPLY
    24243 TSM:FPAR
    24261 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:
    26268 !TSM:FPAR:FAIL
    26269 TSM:FAIL:CNT=2
    26271 TSM:FAIL:DIS
    26273 TSF:TDI:TSL

  • Mod

    @giebek could you describe the problem, what your setup looks like, and what you have tried so far to troubleshoot it? There are 137 posts in this thread so it is a bit hard to figure out which problem you are referring to.

  • @GieBek

    6137 TSF:MSG:SEND,255-255-255-255,s=255,c=3,t=7,pt=0,l=0,sg=0,ft=0,st=OK:

    Imo this indicates your node doesn't have a NodeID yet. When using RS485 you have to assign the ID's manually in the sketch, auto doesn't work... (e.g. #define MY_NODE_ID 123)

  • Thanks for the answers.
    And even more thanks to the rejoe2

    #define MY_NODE_ID 123

    it helped 100% the transmission went, domoticz sees children.

  • hello MySensors friends,

    I am currently making a node based on an arduino Mega 2560 with transport via RS-485, the build page says that we should use the MEGA pin 46 & 48, I was wondering if I would like a reference for this. in the sketch.
    Second question; can I use pin 47 for the DE pin with:

    #define MY_RS485_DE_PIN 47

    I haven't tested anything yet, so actually I just ask a lazy question 😉

  • Hello, I would like to better understand the concept here. It sounds like we still need a gateway connected to a controller (serial, Ethernet, WiFi, etc.) but the interface between gateway and multiple nodes is over wired RS485 serial interface. Please confirm. Thank you for your great efforts!

  • @apl2017 Yes, also for RS485 variant you'll need a gateway. Only the communication between the gateway and the other nodes is handled over RS485, connected to a second (typically software) serial interface (for remote nodes, you may just use the hardware serial interface to connect the RS485 transceiver, if you do not need debug output; but imo this option is not recommended for beginners).

  • @dzjr said in 💬 Building a wired RS485 sensor network:

    hello MySensors friends,

    I am currently making a node based on an arduino Mega 2560 with transport via RS-485, the build page says that we should use the MEGA pin 46 & 48, I was wondering if I would like a reference for this. in the sketch.
    Second question; can I use pin 47 for the DE pin with:

    #define MY_RS485_DE_PIN 47

    I haven't tested anything yet, so actually I just ask a lazy question 😉

    I have it working, so you don't have to adjust anything for a Mega, and pin 47 for DE also works!

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

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

  • @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.

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

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

  • 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 ?

  • @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

    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).

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

  • 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!

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

    ng to build

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

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

  • 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):

    You can read more here:

  • @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.

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

  • @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

  • 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

    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

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

    for information

    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)

  • 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 🙂

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