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

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1answer
20 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 ...
0
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1answer
62 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 ...
5
votes
2answers
374 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 ...
1
vote
1answer
42 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 ...
0
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1answer
110 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
78 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 ...
4
votes
1answer
191 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 ...
0
votes
1answer
56 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 ...
2
votes
1answer
93 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
97 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 ...
0
votes
1answer
52 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
79 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 ...
0
votes
1answer
44 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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votes
1answer
45 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 ...
1
vote
1answer
85 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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2answers
88 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 ...
1
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2answers
72 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 ...
4
votes
1answer
102 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
20 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
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3answers
180 views

UART on dsPIC33EP512MU810

I want to continuously transmit the data on the UART2 of my dsPIC33EP512MU810 . UART2 Tx ...
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2answers
157 views

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 ...
5
votes
1answer
293 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 ...
3
votes
1answer
69 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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1answer
84 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 ...
1
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1answer
264 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 ...
3
votes
1answer
447 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 ...
1
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1answer
71 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 ...
1
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2answers
60 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 ...
0
votes
0answers
95 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 ...
4
votes
2answers
784 views

RS485 terminating resistor power rating

As far as i know rs485 specifies a bus common mode voltage of: -7V to +12V the terminating resistor is 120ohm , using VxV/R , yields high power rating to the resistor , certainly more than 1w . (...
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votes
1answer
170 views

RS485 problem, losing nodes [closed]

I have 5 nodes that are connected to a server with RS485. The distance between nodes is 5.5 m. I used a shielded twisted pair cable and I terminated the line with a 120 ohm resistance. The power of ...
2
votes
2answers
94 views

Protecting a low voltage (RS485) bidirectional bus from direct mains connection

I have a bunch of devices that will sit on a two-wire bidirectional RS485 bus (DMX-like, but not quite DMX). I'm trying to protect against an edge case, where a user mis-wires a ballast, and ...
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0answers
33 views

running modbus using cat-5e structured cable plant [duplicate]

We're looking to install some temperature/humidity monitoring in an existing facility. Installing new cabling would be very expensive because of the nature of the plant. Using the existing cat-5e ...
1
vote
1answer
97 views

TTL output levels on SN75176 transceivier

I have a system that communicates between two subsystems over a distance with UART. The UART signals are converted to RS485 by using the SN75176 differential bus transceiver. A microcontroller on one ...
3
votes
1answer
199 views

Finding cable impedance, to determine RS485 line termination

We have some Belden 6341PC cable which will be used with some RS-485 communications equipment, which of I'm learning will need line terminators. I'm told the resistor values needed should match the ...
2
votes
2answers
109 views

What is the RS-485 line wire series resistance limitations?

Just tried to simulate the communication line with the series resistance in it: As you can see even at 1 MBPS the signal at the "receiver" is fairly good. I'm pretty sure that this will be OK to ...
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4answers
189 views

Missing component on the Usb to RS485 converter [closed]

I have a Usb to RS485 converter that was dead on arrival. I opened it up to see if I could fix it to find out that it was missing a component on the top left corner. This is a very common converter. ...
0
votes
1answer
198 views

Microcontroller SDLC interface

I want my AVR microcontroller based device to communicate via SDLC (Synchronous Data Link Control) physical interface with another device, SDLC is RS-485 based. The SDLC interface must have the ...
0
votes
3answers
218 views

RS485 transmission line high voltage protection

I have a reuirement to protect RS485 transmission lines from up to 500v which may be prolonged. Basically I have 485 data within the same cable as 500v, and the cable is under water, so sometimes if a ...
0
votes
1answer
56 views

way to display the data from a multi function meter [closed]

I have a multi function meter and i want to collect the data and display it. My idea was to create a api for serial communication?? will the idea work or is there any other better way?? the meter uses ...
2
votes
1answer
166 views

RS-485 differential signals won't “cross”?

I have an issue where a certain controller which uses a RS-485 tranceiver (unknown, due to third party device in epoxy resin) sends data on a bus so that signal levels won't cross. The signal looks ...
0
votes
0answers
301 views

Differences max485 and max13487

In my application, I need to transmit data between two arduinos, one as a master and the other as a slave using 485. The arduinos are connected to these modules, which have a Max485: Schematic: With ...
1
vote
1answer
221 views

RS485 waveform distortion

I was checking RS485 signals with an oscilloscope and saw some waveforms which look distorted (see right side of image PIC1). See schematic for test points TP1, TP2. Setup Probe 1:- TP2 and GND ...
0
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1answer
159 views

long stub length rs485

TI recommends their low-data rate transceivers to cope with long stub lengths for RS485 networks -- eg Page 3 of http://www.ti.com/lit/an/slla272c/slla272c.pdf I want to use an isolated interface, so ...
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0answers
139 views

Problem with Pyserial read time

I'm building a RS485 network with rpi3 as master and a bunch of c51 mcu as slaves. After sending an address, the master waits for the slave to respond and then starts to send data. I'm using Pyserial ...
0
votes
1answer
87 views

TI SN65HVD75 RS485 is not working while transmitting

Now I am doing a project with TI SN65HVD75 RS485 and nrf52832. The project is converting RS485 to ...
1
vote
2answers
490 views

Powering SN75176 for RS485/UART communications over long distances

I have an application where a master/transmitter system communicates with a slave/receiver subsystem over an arbitrary distance. The two systems each consists of a microcontroller and some analog and ...
2
votes
1answer
142 views

Do I need ground for RS-485 if it is galvanically isolated?

I am designing an RS-485 communication. The communication interface is isolated. So, only the noninverting and inverting line will be connected outside to the cable. I know that I have to include ...
2
votes
1answer
255 views

Protocol for RS485 network?

I have to build a sensor network which communicates over a single RS485 bus. The network could have tens of nodes. The problem is that I have to control access to the shared bus and find a way to ...
2
votes
1answer
290 views

Besides address is there other limit on max nodes via RS485 Modbus-RTU

Since there is 1byte for nodes' address in Modbus frame, the limit should be around 256.But some say there is some limit on this scenario (RS485, Modbus-RTU) base on chips and wire. Chips support ...