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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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Arduino RS485 shield to RS485 temperature & humidity sensor

I’m try to get data from rs485 is not work please advise to me. 1. Try to connect PC usb485 to DY-MD02 is work. Send command “AUTO” or “READ” 2. Try to Arduino rs485 shield to DY-MD02 is not ...
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NodeMCU Modbus with Dotech DPX200

I've been trying to interface between a NodeMCU and a Dotech DPX200 Pressure Multi-Switch over Modbus RS485 using a MAX485 Module and after a few suggestions I managed to communicate with the Simply ...
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1answer
27 views

NodeMCU Modbus interfacing with Pressure Multi-Switch

I've been trying to interface between a NodeMCU and a Dotech DPX200 Pressure Multi-Switch over Modbus RS485 using a MAX485 Module for the past few weeks, going through nearly every Modbus post on this ...
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1answer
33 views

Connecting multiple RS485 together

I am trying to build communication across multiple Arduino using RS485. When i am trying to connect 3 Arudino nano together using breadboard my code doesn't reach slave where as if i just if i do ...
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1answer
31 views

Arduino Hardware serial pins with RS485

I tried asking a question in my earlier post - SerialEvent with RS485 communication it helped me understand Hardware serial and Software serial but i had few more questions for which i started this ...
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47 views

SerialEvent with RS485 communication

I am not expert in Arduino programming but i can understand lit bit, while doing review i came across two sets of programs one using serialEvent and one with RS485 library, Now my problem is with ...
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0answers
68 views

RS485 Slave doesn't receive any message

I am trying to follow below design to communicate with 2 Arduino Nano, using the example shared here https://github.com/RalphBacon/RS485-Serial-Data-Transmission. When i look at data my slave never ...
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40 views

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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160 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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70 views

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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17 views

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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54 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
64 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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120 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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873 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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67 views

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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53 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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212 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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108 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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450 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
284 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
637 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
361 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
211 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
151 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
529 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
12k 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
10k 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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2answers
329 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
499 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
310 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
368 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
537 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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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
10k 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
684 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 ...
3
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1answer
888 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
405 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
233 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 ...