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Questions tagged [rs485]

also known as ANSI/TIA/EIA-485, TIA/EIA-485, EIA-485 or RS-485, is a standard defining the electrical characteristics of drivers and receivers for use in balanced digital multipoint systems. The standard is published by the Telecommunications Industry Association/Electronic Industries Alliance (TIA/EIA).

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Unable to read data more than once via Modbus RTU

I'm a newbie to this forum so kindly excuse me for any errors. I'm using an Arduino Uno and Max485 (RS-485 to TTL) to communicate with a Power meter, but I'm able to receive the data from the Power ...
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28 views

Arduino Uno & ESP32 communication using RS485

I am trying to establish a communication between Arduino Uno ( Master) and ESP32 (Slave) using RS485 protocol (using MAX485 module). I have successfully done this between two Arduino Unos. ...
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RS485 Serial Communication not working with Arduino

I am trying to control 2 devices with my arduino using RS485 communication. Basically switch on device 1 for 5 seconds when I send 'g' to the master. And switch on device 2 for e3 seconds when I send ...
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PLC with Arduino UNO [duplicate]

In my current project I have to communicate with 10 different devices with PLC. PLC is the master. When input comes from PLC to a device, the Arduino controller through RS485, I want to check the ...
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32 views

RS485 Arduino Communication Issue

Friends, I am trying to achieve half duplex communication between two Arduinos using RS485 Protocol. The hardware I am using is a MAX485 module and an Arduino Uno. I am using the SoftwareSerial ...
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1answer
30 views

Cannot read modbus data repetitively

I try to communicate with 2 RS485 sensors (pH and EC), but I have some troubles with my code. First, I tried to get data from just one: The function in charge of request sending: String GET_probe(...
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1answer
79 views

Electric meter with Arduino and RS485 module

I'm a Arduino newbie. I have an Electric meter with an RS485 output. I want to get the MeterID value over the RS485 module and the Arduino. I just have document from manufacturer. Sent by computer : ...
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231 views

Arduino master/slave communication using RS485

I am using Arduino Uno as a Master Device and 3 Arduino Unos as slave devices. I am sending data from each slave to master after every 3 seconds continuously, and is going to execute further logic ...
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RS485 Wrong Results in Serial Monitor(Controllino) - Right Results with Logic Analyzer

After searching the internet and trying different examples, I always get the same wrong response in the serial monitor. Picture 1 shows the wrong results. At first i thought it was decimal and I just ...
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39 views

Arduino as Modbus RS485 slave using only 2 Digital pins

I want to use RX(0) and TX(1) Pins to make Arduino as an RS485 slave. To do this I am using MAX485 IC (Breakout board) https://datasheets.maximintegrated.com/en/ds/MAX1487-MAX491.pdf The problem here ...
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119 views

sending data with rs485

I need to read acceleration data with ADXL335 using ARDUINO MICRO (or NANO) and send this data with RS485 module to another RS485 module connected to an ARDUINO UNO (300m between RS485 modules). ...
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79 views

Arduino Modbus slave error

I am trying to use Arduino as Modbus- RTU slave and Raspberry Pi as a Modbus master I have interfaced Max485 (RS485 to TTL converter) with Arduino and Rs485 to USB converter in Raspberry Pi, Initially,...
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331 views

Arduino Modbus - Rtu slave with Raspberry pi using MAX-485

I am trying to use Arduino as Modbus- RTU slave and Raspberry Pi as a Modbus master I have interfaced Max485 (RS485 to TTL converter) with Arduino and Rs485 to USB converter in Raspberry Pi, Initially,...
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2answers
195 views

Problem with modbus communication between two arduinos when writing more than 27 registers

I have the following problem: I want send 200 registers from a modbus master to a slave. Both are arduinos. I can't send more than 27 registers. When I send more i get the Errorcode 255 which means ...
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1answer
527 views

Using Modbus-RTU with Arduino and temperature controller

I'm trying to connect with a 4 channel temperature controller using Arduino Modbus Library. This is a part of my temperature controller datasheet. It has register for read PV of each channel. I have ...
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1answer
359 views

Trying to power 100 Arduino's from single power line [closed]

I'm trying to power up to 100 Arduinos that will be spread across a 25m wall using a single power line. The idea is each Arduino will have a few a few buttons, leds & an oled screen and will all ...
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2answers
177 views

Arduino network with minimum wiring

For a parking management system I am going to create an Arduino network. An Arduino with an ultrasonic sensor will be placed above each parking space. If car is parked at specific location Arduino ...
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3answers
132 views

DMX on the Arduino without additional driver chip

I recently saw this video where the creator controlled a DMX light via the Arduino. There he used the pins 3 and 4 for the data on the Arduino Duemilanove. As DMX library he used DmxSimple. Based on ...
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1answer
2k views

How to make I2C work on RS485?

I'm trying to optimize the communication (minimize wires) on a project where I can control a motor and toggle some 230V devices by using RS485 and I2C. On this project, I'm using an Arduino (Mega) ...
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1answer
435 views

Arduino Mega RS485

I am following the instructions from this page to set up RS485 communication between two Arduinos. https://arduino-info.wikispaces.com/SoftwareSerialRS485Example My wiring varies slightly from the ...
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1answer
10k views

Modbus RTU controller monitoring with arduino and RS485 module

I'm a medium user in Arduino. I baught a pHmeter controller with RS485 output (MODBUS RTU protocol). I want to get pH value read by the controller over RS485 module and Arduino. According the ...
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2answers
9k views

Arduino ModBus RTU master communication with Power Meter problem

i have an arduino UNO with RS485 module. I have made this connection: And i have an problem with communication of this module with power meter "InePro PRO-1Mod" (datasheet) over ModBus protocol. I ...
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6k views

Arduino mega to Arduino mega commuction with RS485

I trying to communicate two Arduino mega's using RS485. Am able transmit thought the serial channel but another end is not receiving.I have used the below diagram as reference to circuit The Code ...
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2answers
298 views

Problem using ICSC (by majenkotech) in RS485 bus

I want to communicate with an RS485 Bus consisting of 5 Arduino Pro Minis as slaves and one Arduino Mega 2560 as Master. I found a great library for this. According to the documentation provided by ...
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2answers
462 views

What Ohm Termination Resistor is needed for this schema ? What, Where and How?

I'm building a Master-Slave system using some arduino pro mini as slaves and a Mega 2560 as Master to communicate over RS485 config via MAX485. Since i'm newbie in RS485 i know that i need to put some ...
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1answer
295 views

Problem communicating between arduino UNO R3 and Mega 2560 via MAX485

I want to send data between Arduino Uno and Mega via MAX485. When I set the data Enable pin to HIGH on Mega (to transmit data) and set the same pin on UNO to LOW (to receive data) I can read data ...
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2answers
333 views

Transmit data to long distance (120m)

I want to transmit data from multiple sensors to an Arduino and distance would be approximately 120 meters. What protocol or configuration should I use? Actually I am trying to read values from 5 ...
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1answer
55 views

Make Sure Digital pin is high before Serial.write()

I have the following code for a TTL to RS-485 Adapter Module [...code] digitalWrite(DE_PIN, HIGH); //directional control for adapter Serial2.write(Message, Size); Serial2.flush(); digitalWrite(...
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1answer
522 views

Communicate between NodeMCU ESP8266 gateway and multiple sensor nodes

What is the best wired way to communicate between multiple NodeMCU ESP8266 boards for home automation. Every room should get at least a light, temp, PIR and xx relay modules to switch things on and ...
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0answers
1k views

Problem in MODBUS RTU communication between two arduino's

I am doing a project to communicate between two Arduino's using MODBUS RTU protocol. I have set one Arduino as the master and the other as the slave. The slave Arduino reads the analog value from a ...
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2answers
1k views

rs485 and serial ISP

I made a couple of arduino mini pro and esp8266 pcbs with an rs485 transceiver just to find out that I forgot to think about in-system-programming: Assuming that I don't need to disable the ...
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4answers
9k views

RS485 Multimaster Communication with collision avoidance

I'd like to know if there is an easy way to implement communication between multiple arduinos that avoids collisions using the RS485 module. My setup would have multiple masters that send messages ...
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1answer
1k views

Why ModBus RTU Master-Slave Dont Work

I have two mega arduino and want to them communicate with modbus rtu together, i use below link circuit for this : http://www.microcontroller-project.com/rs485-communication-between-arduino-mega-and-...
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1answer
1k views

Arduino serial non-blocking

I'm writing an Arduino program to communicate with another module using RS485, so I need to control data flow with one pin. But when I set the pin to HIGH (line 88) it almost instantly falls (as you ...
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1answer
2k views

RS485: is “Y” multidrop allowed?

I imagine that the proper way to implement an RS485 multidrop bus is the following: What happens if, in order to save cables, I connect the same 5 nodes above using this other topology? Will it ...
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2answers
673 views

Hardware network-infrastructure for a fully-arduino-based home-automation project

As already mentioned in another question, I'm spending LOT of time planning the home-automation system for my new house (currently still in the "still building" phase). Even if started only as a "...
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2answers
12k views

Arduino sending data over MAX485

I would like to introduce myself as a student from Czech Republic. I'm currently I'm working on a Meteostation project. I've got Arduino set up, with plenty of weather sensors, as well as WH1080 ...
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1answer
855 views

Arduino throwing error while using modbus RS485 code

I have been trying to make a communication with my industrial drive. All I want to do is read a few values of drive, like current, voltage etc. For that I am using a library: I don't understand why ...
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3answers
1k views

RS485 bus voltage?

Does anyone know the voltage situation regarding multi-drop nodes on an RS485 bus please? Nick Gammons RS485 article shows 2 different hardware configurations, one using 5v devices, and another using ...
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0answers
1k views

Pelco D Library for Arduino

Does anyone know of any Pelco D libraries available for Arduino? I already have a PTZ joystick controlling 3 PTZ cameras, but I would like to add an Arduino 'intelligent' controller capable of ...
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2answers
4k views

Long Distance Communication with Arduino

I am reading the value of six potentiometers with a TX Arduino and receiving that data and applying those numbers to a motor using serial. It is working fine through TTL but I am going to need to do ...
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1answer
379 views

Modbus master arduino code is throwing weird errors on upload

I am using the following https://code.google.com/p/simple-modbus/ arduino master library code. In order to communicate with my industrial drive. All seems right but I am getting some weird errors. I ...
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0answers
64 views

Multi-drop RS485 device control v1.0 - why is limit for “TIME_BETWEEN_MESSAGES ”?

I am going to use Nick's rolling-master system library (http://www.gammon.com.au/forum/?id=11428) in my home project. For first experiments and testing, I have: - BAUD_RATE = 9600 - max adress = 2 (...
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1answer
226 views

Interfacing Gammon's RS485 with computer

I'm using the non-blocking RS485 Gammon's library for Arduino (as shown at http://www.gammon.com.au/forum/?id=11428) to handle the communication between some arduinos. Now I'm having trouble to add a ...
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1answer
1k views

Problem in RS485 Communication between Arduino and PC

I'm trying to sending and receiving data via RS485 communication. Interfacing Arduino and PC(laptop) using SN75176 RS485. I wrote a program to send a string "Hello" from arduino via Tx pin. My ...
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2answers
2k views

Serial: What is different between Gammon's RS485 (blocking) and RS485 “non blocking” libraries?

The RS485 master-slave communication library on Nick Gammon's page http://www.gammon.com.au/Arduino/RS485_protocol.zip is working for me OK, but on the same hardware wiring is not working for the non-...
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1answer
2k views

Modbus Communication protocol for Arduino as Slave

I have an Arduino Uno board, with these components: rs-485 Modbus module shield Multiprotocol radio shield board for Arduino In addition I have a level sensor which reads either 1 when it is above ...
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1answer
80 views

RS-232 is a protocol or a cable?

RS-485 and RS-232 are a type of communication protocol or a type and cable? I studying these serial communication protocols and each place refers to the RS-232 / RS-485 in different ways. Some ...
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4answers
5k views

How to interconnect multiple Arduinos with a Rpi to control home-lights/switches

While planning the lightning infrastructure (wall-switches and lights) of my new home (it's still under-construction) I choosed to go through the "automated route" way and due to my background (I'm an ...
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2answers
1k views

How can I get a unique address for all my Arduino boards while in RS485?

My attempt is to know how to identify the board I'll be sending parameters to in a serial connection like rs485. I'm asking because I will have about 11 or so mcu's as "Rx slaves" while my pc is the ...