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Questions tagged [rs485]

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

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51 views

Raspberry Pi - Connect and power RS485 device

I am trying to connect a Raspberry Pi to a OSDP card reader. The reader communicates via RS485, and is powered by 9-27V DC. Unfortunately, I have only briefly been able to succeed with a serial ...
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1answer
42 views

RS485 three nodes (Master, Slave1, Slave2). Slave1 disconnects whenever Slave2 is connected [closed]

I have an issue with RS485 comm where one of my slave devices disconnects as soon as the other one is connected. They are on two different addresses. Master and Slave2 are terminated. Slave1 is not ...
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5answers
55 views

RS485 IC Termination Resistor Configuration

I've made a mistake on a design, that went into production... It was built like the drawing on the left, with R702 to 5V and R703 to GND, it should have been backwards... like the drawing on the ...
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1answer
24 views

Low current rs485 and wake up

I have the following question: I have to do a network of devices based on MCU. This network in a RS485 and the device is battery powered. For save the battery I put in sleep mode the MCU and I ...
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1answer
34 views

LIN to RS485 and back to LIN

I am currently communicating between two microcontrollers using a single pin and the LIN protocol over a short distance of 0.2m. Now I would like to extend the distance up to 5m by differentially ...
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3answers
90 views

ground connection for isolated rs485 [closed]

Is it necessary to connect isolated grounds for 2 different isolated RS485 nodes? For instance the following isolated RS485 breakout board doesn't have any GND connection in the board. https://www....
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2answers
67 views

Connect RS422 interface with Arduino Uno

I have a fishfinder,Lowrance Carbon HSD 7, and I want to connect it with the Arduino Uno to let the fishfinder transmit the Sonar data and GPS data via NMEA0183. According to the maker's site, the ...
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1answer
73 views

ModBus Timeout Error

Anyone very experienced with Modbus & RS-485??? My task is to control a DC motor using micro PIC24. The motor setting like the angle, delay, start/stop, duty cycle, etc will be sent from PC using ...
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1answer
59 views

RS485 Waveform while Receiving Data

I was testing the RS485 Circuit, below is my circuit and I connect J5 to my PC using another RS485 to USB converter. In PC through Modscan software I was monitoring the polling and response, a twisted ...
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2answers
48 views

I need to switch between RS485 signal and Digital input port

I am looking for a solution where I can use RS485 along with the 2 (two) digital input port on the same line but both will be used one at a time. When there is RS485 communication (selected through ...
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1answer
79 views

MAX485 suddenly drawing too much current and output voltage levels are not right

I have two PCB that I designed and they are made by a PCB manufacturer (so they are identical). They use a MAX485CSA to communicate but suddenly one of them is drawing too much current, on a normal ...
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2answers
44 views

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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1answer
66 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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1answer
44 views

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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0answers
62 views

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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2answers
83 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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2answers
59 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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2answers
103 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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32 views

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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0answers
52 views

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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1answer
115 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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2answers
73 views

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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3answers
52 views

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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2answers
46 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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2answers
190 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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1answer
135 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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1answer
170 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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1answer
130 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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1answer
268 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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1answer
126 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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1answer
50 views

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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1answer
43 views

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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1answer
82 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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3answers
553 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
59 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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1answer
224 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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2answers
82 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
301 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
67 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
110 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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2answers
349 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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1answer
62 views

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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2answers
83 views

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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1answer
75 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
51 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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1answer
154 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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3answers
173 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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2answers
87 views

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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1answer
280 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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0answers
23 views

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