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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4answers
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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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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
548 views

How to solve Atmega 16A Serial write (println) hang with Arduino Uno firmware?

For doing some experiments I bootloaded an Atmega16a with Arduino Uno. I am powering my Atmega16a from Arduino UNO. I am not using any external clock. Atmega16a is connected to a breadboard. For ...
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1answer
14k 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 ...
3
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2answers
5k 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 ...
3
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1answer
1k 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 ...
2
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2answers
547 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 ...
2
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2answers
14k 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 ...
2
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2answers
322 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 ...
2
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1answer
361 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 ...
2
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1answer
705 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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3answers
214 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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2answers
264 views

Arduino UNO and RS485 Communication Problem

I am learning Arduino, a beginner in programming. I want to use Arduino UNO to connect a wind direction sensor RS485. The problem is the output in the serial monitor, the return data from the wind ...
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4answers
11k 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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2answers
14k 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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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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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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2answers
619 views

Standard Length Messages over RS-485

I am a bit confused. So I want to send messages between two arduinos over RS485, but these are not fixed length, naturally, I have to send the length of the message or add a delimiter to understand ...
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2answers
2k 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 ...
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1answer
170 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
57 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
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
730 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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1answer
481 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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1answer
667 views

RS-485 with Arduino

I have two Arduinos on a RS-485 line, one acting as a Master and the other as a Slave. The Master simply transmits information to the Slave, which parses it. They work fine when the Master is ...
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1answer
179 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
792 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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0answers
128 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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0answers
183 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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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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0answers
67 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 (...
0
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1answer
369 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 ...
0
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2answers
408 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
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 ...
0
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1answer
3k 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) ...
0
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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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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
63 views

Serial Module Echoing a `0x00`

I am having a problem with a MAXIM Serial module (Config A) with a simple repeating code from COM port. When sending a character (k:0x6b) I receive a (0x00) echo. Without the module and just ...
0
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1answer
99 views

NodeMCU: Wiegand not working for one device, while working for another

I'm using a NodeMCU, and a working code for reading Wiegand data, with this library. I managed to successfully read the Wiegand signal from this device. However, I also have this new AR-721H device, ...
0
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1answer
24 views

one Arduino with RS485 and Ethernet shields: does this work?

I'm planning to wire a few Arduinos together via RS485, and have one of them act as a hub that collects information from the others and presents it via http on an Ethernet connection. For instance ...
0
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1answer
33 views

Serial Enable Maxim RS485 Pin

If I want to use a MAXIM 485 for a RS485 communication, is there any option to include the Control DE and RE' pin in a natural manner in the code, instead changing the control pin everytime I made a ...
0
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1answer
544 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
93 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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2answers
530 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
882 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
84 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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0answers
31 views

Can I use an UART RS485 board with DMX simple library?

I want to use DMX512, and found a library DmxSimple, which uses a single (non UART) GPIO pin as output (see DmxSimple.wiki. I currently use a TTL RS485 board, which does not have any TVS/polyfused ...
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0answers
68 views

Reading a simple sensor with Modbus RTU on Arduino Uno

I'm integrating a wind direction- and speed sensor with an Arduino. It communicates over RS485 Modbus RTU, which I don't have any experience with. The documentation is very short, and it just says: ...
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1answer
200 views

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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0answers
44 views

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 ...