arduino 485


So to start with, what is rs 485 recommend it’s done that 45. It it’s a hardware communication protocol, basically it’s a specification of wiring pinout and devices which transmit and receive on that wire, so that’s. What rs 485 is in a nutshell and Modbus what’s mob boss. Well, mob boss is a software protocol which is used in in electronic communications. Modbus is used for PLC’s and lots and lots of different devices and specifically, what mob boss says: it’s it’s a set of software rules which govern how to interpret data basically and how to transmit data so where’s models used. Well, I just highlighted virtues of PLC’s, but Markus is also used on normal, well, in fact, any device – and this is one foots device. This is my solar charge controller. I can use the Modbus protocol in order to get data from this unit. So, to start with what’s what well rs 485 uses the ethernet cable or, as you might know it so if I am ever net cable and plug it in, I could transmit and receive data from the other end, of course, but with the Arduino it doesn’t need To be support, rs, 485, so what you have to do is you have to get a little converts a device like this, and this is an rs 485 to TTL, converter, board and I’m, going to wire that up to the Arduino and I’ll see the wiring in A bit but anyway so we’ve got the wiring soldered down now mob boss.

You can get a library a lot. We know library which people of very we spent the last time on, and if you have to download this library, you can basically make use of models. Therefore, make use of whatever data is available through the device which you’ve connected. So I think what I’ll do next is to show you the wiring I’ve got the Nano and I’ve got the rs 485 to TTL converter ler. Now the wiring is as follows. So you get your adalat cable if you like, or the rs 485 cable and plug it into whatever the device is, and this is gon na, be the slave device and then the other end, if you foil it right down. That goes into the converter. Now, in rs 485, I believe there are four wires how it’s used for communication I’m gon na go into the rest. What are those four wires in my particular device? Two of them identical so I’ve got two identical and another two are identical and therefore I don’t actually need to use the four pin like in these two pins. So there are any pins in the collector but I’m only going to use two pins. So, according to your documentation for your device, you’ll be able to find out which those two which two of those pins are the ones that you need to use and usually they’ll, be labeled in documentation as a and B in Fianna little as B and a so In the specification document of the device, you should be able to see that in there somewhere as well, there are ways to find it out by being fast, but anyway I won’t go into that.

So we found the a and B pin of the eight pins and then I’ve got the rest back. Okay in the pin. I was writing. Just get this to focus properly. You can see the IDE I am aha, Oh so di is driver in the e is driver, unable driver means, friends in tobacco, Ari is receiver, enable and ro is receiver out, and these go to the I is going to txd on the arduino d e is Going to ds3 on the arduino r e is going to d2 on the arduino and ro is going to t XP on the arduino okay. So next you can see over this side. There are two pins, a and B, but also at the end. You can see ground and VCC and VCC, of course, here’s the five volts and ground mr. grant and that’s pretty much it for the wire off of this little device so wandering to the United States.


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Originally posted 2016-07-23 14:46:01.

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Comment (22)

  1. R0 is going to Rx on the arduino. In the narration you say it goes to Tx on the arduino. You should comment that.

  2. Hey man! Great videos. Just wondering if you could explain exactly what the rs485 module is doing that the serial ports on the Arduino can’t do? Thanks a lot!

    1. Hi! ‘Serial’ means that data is transmitted in series. But there are all sorts of different protocols which govern how that data is transmitted and received. My understanding is that the Arduino transmits serial in TTL. Old computer COM ports are RS232, and my device uses RS485. They are just different ways to communicate. Different syntax if you like. 🙂

    2. RS232 is 1:1 communication or one comport to one device.
      RS485 is 1:n communication or one comport to many devices.

      The number of devices is set in the standard and is beyond the scope of this answer.
      Also, the the wiring and the voltages are covered in the specs as well.

      So what the author is doing in this instance is actually converting RS232 to RS485 with that little interface board between the solar controller and the Arduino.

  3. Your video could be very useful for my project. I have 2 energymeters, one that measures domestic power usage and the other measures power generated by solar panels. Do I need 2 TTL to RS485 modules, or can both meters communicate over A and B to one RS485 module with the arduino?

  4. its great & thank you

    now i need some help – arduino used to read datas from VFD via Modbus Communication. how to do????

  5. How Can I read address 30002 with 2 register? I need to read volume flow of whater. Using modscan32 and a usb adapter for rs485 I can read the correct value, but with arduino and this library the read value is different. According to the manual address 30002 is read as inputRegister.

    I’m using the mega arduino and the RS-485 TTL MODBUS converter

    I am using the IFC050 flow sensor (modbus manual link below) look at page 12:

    What’s wrong with the code below?

    //Code used in the project.

    #define MAX485_DE 3
    #define MAX485_RE_NEG 2

    ModbusMaster node;

    void preTransmission(){
    digitalWrite(MAX485_RE_NEG, 1);
    digitalWrite(MAX485_DE, 1);

    void postTransmission(){
    digitalWrite(MAX485_RE_NEG, 0);
    digitalWrite(MAX485_DE, 0);

    void setup(){
    pinMode(MAX485_RE_NEG, OUTPUT);
    pinMode(MAX485_DE, OUTPUT);

    digitalWrite(MAX485_RE_NEG, 0);
    digitalWrite(MAX485_DE, 0);


    node.begin(1, Serial1);


    void loop(){
    uint8_t result;
    uint16_t data[6];

    result = node.readInputRegisters(30002, 2);

    if (result == node.ku8MBSuccess){
    Serial.print(“Flow: “);

  6. Hi on Phoenix Contact rs485 module I have d(a) d(b) t(a) t(b) how to wire up ???? What means this signals to TX rx etc

    1. That’s RS422 by the sounds of it. The labeling on your terminala are unfamiliar, so take your Phoenix Contact manual and look us the wiring to RS485. In RS485, there is only 2 wires to work with, so a 50% chance you’ll get it right the first time

  7. Ground. You are probaly lucky in that there is an undocumented connection, but you should really connect a ground through on the RS485 lines. Otherwise, the A & B may go outside the range ‘Ground to VCC’ on the RS485 chip. And this is usually unpleasant.

  8. hi
    I used the same code that u did on video and I am using growatt PV inverter to get my reading on serial monitor using arduino uno and rs485 module but I am getting gibberish symbol and characters in my output…
    need help urgently!! thank u in advance

  9. hello Antony I have two things that I need to do at the same time, control the opening and closing of two Y/N valves and send and receive information from a sensor that has a Modbus communication implementation done with :”MODBUS serial communication via serial interfaces such
    as RS232, RS485 “. for the moment I successfully done the Y/N valves with a relay that connects the alim with one or the other one. but for the moment I have no idea where to begin to connect to the other sensor to the Arduino, I am beginning to learn Arduino. I have some Modbus codes that I need to send to the sensor to do what I want, give it the sensibility value, start the measure, and others, and after the measure is done to send back the data, is it possible to do dis with this board, no? I would love if you could give me some guidance, as it is important for my actual work. best regards, hope to receive news from you, Franco


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