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Questions tagged [rs485]

EIA RS-485 is a serial communication standard using differential signaling.

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Differential signal isolation

In differential signal circuits (specifically, RS-485), there is usually an isolation between the signal processing / generation stage (eg, microprocessor) and the line driver chip (something like a ...
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62 views

RS-485 works when USB powered, not when main powered

I'm thinkering with a RS-485 connection (modbus) to read out my electrical power meter. The setup is as follows: ESP32 --> MAX3485 --> RS-485 to USB when the ESP32 is powered via USB, on the same ...
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Arduino RS485 Communication

Working on a RS485 IC circuit. It is a point to point communication between two devices connected to each other via MAX485 IC and CAT6 Cable. At 1 or 2 m length of cable, the data transfer seems ...
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Are positive voltage levels valid for RS485?

I am trying to reverse engineer the protocol between an old keypad and a main unit alarm system. After sampling with an oscilloscope and checking the ICs around. I am close to state that the physical ...
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70 views

How to determine the physical location on a RS-485 daisy chain / bus topology?

I am trying to build a "daisy chain" using several Arduinos and MAX485 transceivers. All boards have a temperature sensor attached to it. A 9V battery supply all boards in the chain. I am trying to ...
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57 views

Where to use CAN v RS485

Not sure whether this is too broad a question but... Why would one choose CAN Bus over RS485, or vice versa, as a system interconnect? I have a MCU SBC with multiple interfaces including the two ...
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81 views

RS485 transceiver design

I'm working on a TTL to RS485 transceiver which is part of a bigger project (arduino based) and I came up with the following design: I have a few questions: 1) I have seen very different values for ...
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Addressable RS485

I have a requirement to take a board that interfaced with RS232 and put it on a half duplex RS485 bus. The obvious problem is that at the very least the board firmware will need to be altered to be ...
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Looking for data sheet of the following Modbus Sensors #updated

I'm a noob in this area, please ignore any stupidity and lack of info and any help is appreciated and I'm ready to provide all clarification on the post if by chance any info is missing. So i have ...
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Controlling a L510 inverter with Arduino using RS-485

I'm trying to control a "IGBT Drive Inverter Motor Speed Regulator" model "L510-202-H1F-P A" with an Arduino. The manual for the inverter is here https://inverterdrive.com/file/Teco-L510-Manual-EN-v2 ...
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98 views

What is 8 pin tssop packed component?232/485 ethernet converter

-size = 2.9mmx3.1mm -GND pin = 1,6,7 connected -7.pin 4.7uh connected
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What communication method shouild I use [closed]

So I wan to control a bunch of devices. I though first of using RS485 but after some digging I figured out this might not work as I don't really have a pure daisy chain. The configuration I would like ...
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MAX485 Receive Output pin current sufficient for optocoupler LED?

I want to recreate a project found at this link where an optocoupler's LED is a driven by the receiver output of a MAX485. Now, my question is, the LED series resistor (R5) value is 470ohms, if my ...
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43 views

How to deal with signal polarity relative to USB-RS485 converters?

I have two USB-RS485 converters. One with skrew connectors that are electrically isolated from the USB (ADAM-4561) and one wire-end version from FTDI chip. I want to connect them together to send ...
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178 views

Purpose of this oscillator (74HCT14-based) on RS-232 to RS-485 converter?

I am reverse engineering an RS-232 to RS-485 converter to understand how it works. I have attached the schematic that I reverse-engineered from the PCB (apologies for the hand-drawn schematic). I've ...
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113 views

How to make a circuit for DMX splitter notification LEDs?

I am trying to make a DMX splitter. Everything works now, but it would be somewhat useful to have notification LEDs, like in the example below. For the input I could use one LED, which I either ...
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169 views

Trying to power 100 Arduinos from single power line

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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123 views

RS485 minimum node spacing - 3 x RS485 device on PCB

I would like to ask something about RS485 minimum node spacing which is described in (Page 5) TI Design guide I would like to create device which consists from 3 existing RS485 devices. My plan was ...
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214 views

MAX487CPA/SN75176BP RS485 IC gets too warm (in DMX Splitter circuit)

Brief I built part of the scheme below (input K2/IC5, optocoupler IC9 and output IC6/K3). IC9 is overheating when I connect LED pars to K3, because voltage is flowing back into pin 6/7. If I connect ...
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95 views

Wire to VDD or GND?

In the circuit below, there are four LTC485 ICs, one input (left), three for output (right). Pins 2, 3 and 8 are going to +5V, as well as GND. So where should I connect them to? Should I wire them all ...
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How to find RS485 UART pins are inverted in the data sheet?

I want to know, how we identify the RS485 pins are inverted. I am using at91 microcontroller? This sam9260 board has four rs485 in which two of them are inverted. ...
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Mega2560 master on RS485 bus stops communicating with VFD when I add another RS485 module

I’m doing a project where I’m building a control panel for a VFD (inverter/variable frequency drive). I’m connecting the two over half duplex RS485 and use Modbus RTU. As a master I use a Arduino Mega ...
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74 views

RS485 to RS232 conversion?

I need to connect a sensor that uses a RS485 transmission to RS232 or something I can read through the com ports on my data logger. I can't use usb ports or virtual com ports due to the program I am ...
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464 views

RS 485 ground signal and chassis

I have a shielded twisted pair running from one device polling several devices in an RS 485 loop. The conditions: The devices are in parallel as they should be. The termination resistors are in ...
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1answer
53 views

RS-485 + iCE40 for better CAN-FD

This is an idea I have been toying with for a while and wanted to get an opinion. When I first heard about CAN-FD I thought it was going to be the answer to this problem. However most mid range ...
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204 views

How to 'wire' RS485 modules?

(Question is completely revised after comments from AndyAka) I want to connect about 15 devices (max) via RS485. However, unlike a normal RS485 cable where stubs/devices are tapped from, I want to ...
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81 views

Help figuring out the interface on this bill validator?

I would like to interface this bill validator to a microcontroller (Arduino Mega). The website says it supports RS232,RS485,Optoisolated RS232 and USB interface. The one I have is currently intefaced ...
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1answer
249 views

Blowing out MAX485 transceiver

[Edit: revised my complete post] I have a problem with a project I'm currently working on, and I would really appreciate some help. I created 10pcs of 100W RGB LED modules that are communicating via ...
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1answer
64 views

Difference between ISL83078EIBZ and ADM483-EAR for UART-RS485 Converter

I want to use UART-RS485 converter circuit as in the attachment. The circuit is working when I use ADM483-EAR Transceiver for U1. ADM483's recommended Vcc value is 5V but it can provide communication ...
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1answer
101 views

How to prevent polling using RS485

I was advised to use RS485 since I have about 7 devices needing to talk to each other (and cannot get CAN to work). Although I want to start simple (two devices where one sends and other receives), ...
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184 views

Switching RS-485 bus

As shown in the graph, I'm trying to use mcu-controlled switches to turn a segment of rs-485 bus on or off (so that only one segment is on at a time). I was considering analog switches but I'm not ...
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power and signal inside shielded CAT5 cable

I'll use a shielded CAT5 cable for RS485 line. The simplified bus structure is drawn in the picture . I have 130 slaves and their isolated part of RS485 IC is supplied from the supply placed at master....
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Setting up a 485 network

I have a problem where my 485 transceiver just get damaged at field, when it's at laboratory everything runs fine, now reading about it I saw that 485 requires a 120Ohm impedance on both ends and bias ...
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61 views

Difference between MAX3430 and ADM483 for TTL-RS485 Converter

I want to use TTL-RS485 Circuit as in the attachment. The circuit is working when I use ADM483 Transceiver for U1. It can provide communication. However the circuit is not working when I use MAX3430 ...
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1answer
50 views

ROV tether: will DC power supply interfere with the control signal?

I'm designing a tethered underwater drone. I think I will use RS-485 for control. I can either place batteries in the ROV itself or supply it with electricity via tether. In the latter case, will DC ...
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122 views

Can I use a twisted pair for 5V and ground?

I'm going to use a RS485 modbus connection which requires a twisted pair. Now I also need power, that will be a 5V line and a ground. The distance will be about 3 meters max. Can i use a twisted pair ...
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139 views

Communication between BMS and PC via CAN/RS485 — where to start?

I am about to obtain BYD B-Box LV Residential battery for my off-grid solar system. The inverter I have is not on the list of compatible ones, which means (according to my local battery supplier) that ...
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RS485 Multidrop Issues

I have an application where we use RS485 to communicate messages to a series of LED Displays on the bus. Our first version of the board seemed to work fine with no problems, however we have made a new ...
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185 views

How does “RS485 Pi” 2-wire transceiver connection work

I'm familiar with connecting a RS485 transceiver with a separate DE wire. However, on this pi hat, they used just Rx and Tx, and I'm not quite sure how it works. (or does it work?) Looks like the ...
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Dynamixel MX106T

I am running into some sort of an obstacle. I have an MX106T (runs UART at TTL) and I wish to control it using RS485. Does any one have any ideas on how to do this? Thank you in advance
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UART on dsPIC33EP512MU810

I want to continuously transmit the data on the UART2 of my dsPIC33EP512MU810 . UART2 Tx ...
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rs422/485 maximum terminator resistor value

as i know terminator resistor value is ~120ohm. But i found a circuit that has 10kohm terminator resitor at A and B lines. In circuit transeiver IC is SP3485E. What is the reason for 10k ? That is ...
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1answer
529 views

RS-485 shield and ground wiring practice

After some reading I was convinced that I have three options: The best: connect A and B lines to a twisted pair, signal ground (SG) line to therd wire in the cable (or to a second twisted pair) and ...
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1answer
80 views

What is the Load referred to RS-485?

This is my first time knowing what rs-485 is and I am computing the power consumption between only two (2) rs-485 transceivers SN65C1167. As I read the datasheet, i became confused on the term "load" ...
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93 views

use RS-485 or Normal Voltage as Input over 10 meters

Newbie when it comes to data transmission, no test equipment or any so i can't verify it actual, much of a idea so i would to ask those who have practical expertise. I have this setup where i came up ...
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1answer
453 views

Will RS-485 work over non-twisted pair?

I have a project coming up that requires serial data comms across a large vehicle with two trailers connected in train. The total length of the vehicle is 100ft, and I need to install several nodes ...
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1answer
741 views

Two MAX3140 (SPI to RS485) connected to one another

I would like to ask if anyone had experience using this kind of IC, i had this school project where i have a lot of sensors using SPIs (each is 10-20 meters away from uC) and these needs to be somehow ...
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1answer
72 views

Identify Single wire communications protocol [closed]

Hi guys I I have uploaded pictures from an oscilloscope. This is the signal that an indoor AC unit sends to the outdoor unit. It uses a single wire for communication and Seeing the PCB it looks like ...
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2answers
65 views

What serial communication interface would work best for data logging when the nearest sensor and main MCU are (at least) 1 meter apart?

I would like to setup a "sensor array" which has 4 sensors attached to it. Each sensor is expected to send data at rates of up to 8 Hz. The data would be shipped off to an MCU that is around 1-2 ...
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124 views

DC energy meter 1000V with RS485 and Arduino getting voltage and current from register issue

I am doing 1000V DC meter with Arduino and RS485. The problem is that when I am sending register value from Arduino I am not getting the output as I want, the output is in hexadecimal, and I can't ...