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

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Enabling RS485 UART driver and receiver at the same time

I am a software engineer so I hope that my question not stupid: I work on board with an half-duplex RS485 transceiver. From the software, I can handle a GPIO to handle the output driver of the ...
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18 views

rs485 interrupt problem in slave reception pic 16f1805

I'm doing a project with communication RS485, I have used the library RS485 in micro C for PIC. I need to use interrupt in reception slave when I simulate with proteus the data is transmitting by ...
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1answer
40 views

Max 485 auto transmission

i am using Max232 and max485 to convert the RS232 pc data to RS485. I got a circuit using these ICs with a transistor and some resitor. circuit is such that RE and DE are short together and tied to ...
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2answers
76 views

Will RS 485 to RS 232 converter change the half duplex mode to full duplex mode?

I am using an RS 485 serial connection through which I need to send S19 files for my boot loader project. Since it is a half duplex mode of connection, I need to toggle a dedicated pin before sending ...
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3answers
273 views

RS485 network ground pin - when to connect?

As many know, one can implement a simple node to node rs485 communication by using only two wires, A and B. Well, the standard specify to connect the ground of the two node together. from Wikipedia: ...
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2answers
58 views

Can we send a file through Half Duplex connection?

I am working on a boot loader design for a kinetis controller. I am using this Terminal application ( https://sites.google.com/site/terminalbpp/ ) . I am able to send texts like, " Hello world" ...
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1answer
42 views

Connection between MDB Peripheral and Arduino

I'm working on making a custom vending machine controller using an Arduino as the master. The bill acceptor I'm using implements the MDB communication protocal, which is (I think) a variant of RS-485. ...
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1answer
80 views

RS485 current source/sink

I'm looking at using the RS485 to communicate between two Arduinos. I'm trying to wrap my head around the current requirements though... If I connect a driver to a receiver through a differential ...
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102 views

Interfacing Energy Meter with Arduino using MODBUS RTU protocol

How do I interface Rish EM 1340 energy meter with Arduino Uno? The meter has MODBUS RTU protocol and RS485 communication port. I am using RS485 to TTL converter for connecting meter to arduino. I have ...
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1answer
41 views

Can I connect 4 wire and 2 wire RS485 devices on the same network?

If so, how? I have 4 wire and 2 wire devices I would like to connect on the same data line. I know you can convert 4 wire to 2 wire easily at the master, but is it possible farther down the line, say ...
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17 views

Connecting L&T Qusar Meter to Laptop using CAS MODBUS SCANNER

I am trying to connect Quasar meter with my laptop. Quasar meter has MODBUS RTU protocol with RS485 communication channel. I am converting RS485 to RS232 and then through serial adapter I am ...
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1answer
71 views

ADM2587 using input uart

I have a design with the ADM2587 in half duplex mode: If I want to receive something over RS485 I pull RE and DE low. This is tested and works good. The same thing with sending: RE and DE high, ...
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1answer
73 views

To connect arduino uno with energy meter

How do I interface between Energy Meter having MODBUS RTU protocol with RS485 communication to Arduino Uno? I am using MAX 485 to convert RS485 to TTL. And I have done coding in ModbusMaster library. ...
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0answers
35 views

How to Map RPI4(RB4) pin to uart4 in pic24fj128ga202?

I am using PIC24f128ga202 for my project which has four uarts we have successfully mapped three uart using re-mappable pins ,but the fourth uart seems to be too difficult to map to (RS485 ...
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0answers
50 views

Connection between a USB to TTL module and a TTL to RS485 module

I have been provided with these two modules: CP2102 USB 2.0 to TTL UART Module 6Pin Serial Converter STC Replace FT232 Module sunkee MAX485 module / RS-485 module / TTL to RS-485 module How can I ...
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1answer
60 views

Connect Schneider EM6400 to ESP8266 and call REST API [closed]

I have a Schneider EM6400 meter whose data I need to send to a web-service. I dont know much about electronics so here it is- How do I do it? My idea is to use an ESP8266. But from what I know, the ...
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2answers
35 views

Redundancy for a databus transmission

I'm going to start a project in my University in a few week. Since it is a collaboration between my University and a very important company I cannot say too much about the project itself. So I try to ...
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2answers
61 views

Profibus DP RS485 Polarity

I am implementing a device which communicates on Profibus DP. In order to get the communication with my Siemens S700 PLC to work, I have to reverse the order of the 'A' and 'B' differential signal ...
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1answer
137 views

Arduino does not receives response over RS-485

I am using arduino uno to communicate with my industrial drive. I am using juan bester library for RS485 communication. Now here's what's happening: When I open serial monitor in my arduino after ...
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1answer
78 views

RS-485 Idle Failsafe Is it really needed?

I'm planning on setting up a sensor network around my house using a Cat5 Cable as both the power source and the signal line for the sensors, I'm planning on using RS-485 Transceivers and and Arduino's ...
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1answer
89 views

Theoretical fastest polling speed for RS-485

I have a system of 36 sensor assemblies that I'd like to quickly poll the state of several times per second. Each one of these assemblies includes a Teensy 3.1 board connected to an analog sensor and ...
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1answer
69 views

RS-485 bus with PoE bus

I'm working on a home automation/security system (Only in my head at this point) and stumbled upon RS-485 transceivers. using RS-485 with PoE seems to be like a great idea to keep cords to a minimum. ...
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3answers
70 views

Transit between RS485 and CAN

I have two transceivers, one for CAN and one for RS485, and both are isolated. Both standards require 3 wires (two differential pairs and one common GND). I am trying to use one termination connector ...
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1answer
132 views

RS485 not working in pic24fj128ga202

I would like to send and receive data between two PIC24F microcontrollers via RS485. Here i'm using SP3485 IC. I've set one microcontroller as transmitter and another one has receiver. My ...
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1answer
91 views

Showing junk data in RS485 Protocol using pic24f?

I am working on Rs485 protocol using PIC24f microcontroller and sp3485c as rs485 transceiver ic . I have kept one pic as master and another pic as slave . when i am transmitting any data from master ...
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1answer
121 views

RS232/RS485 Converter Circuit Receiving Problem

I'm trying to make an RS232/RS485 converter circuit. I used a circuit from http://airborn.com.au/layout/232cnv/232to485.html site and i changed some components on that circuit. Then I established my ...
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1answer
98 views

Modbus RS485 - Voltage greater than 12V?

I have a boiler (Immergas Eolo Star) which has 2 pins where you can connect either a normal thermostat or a "remote control unit" which can also give more detailed information (self-diagnosis) about ...
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1answer
41 views

Differential bus transmission

I am working at a project which requires an application which has some devices connected through a bus (RS-485 || CAN), I haven't decided yet.The problem is that some of this devices are hot pluggable ...
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1answer
145 views

SPI over long distance

I want to connect chips that use SPI protocol to communicate (To be specific those chips are ws2801) the distance may reach 100 meters. How can I solve this issue? through a few days of searching ...
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2answers
48 views

Need to get sensor data from a Arduino Pro Mini to a Arduino Mega that is about 150 feet away from each other

So like the subject line states... Need to get sensor data from an Arduino Pro Mini to a Arduino Mega that is about 150 feet away from each other (maybe slightly less) both operating at 5VDC. Do I ...
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3answers
464 views

Struggling with serial communication over RS 485 using modbus protocol

I have around 60-70 inverters that I want to talk to using arduino over RS-485. The connection that I am making with arduino is according to the attached image. Now I think that my connection part ...
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1answer
149 views

Modbus Rs-485 serial communication and polling with reference to manual

I have connected my slave and RS-485 using serial connection and using my computer as master device. I'm able to poll but I cant figure out which registers I'm polling as shown in image 1. I tried to ...
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1answer
148 views

RS485 Multidrop Issue

I have a multidrop RS485 network with one master (PC with RS232-RS485 converter) and 2 nodes using the Max13487 (schematic attached). Communication is fine in both directions using one node. However I ...
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2answers
92 views

USB to multiple RS485

I'm trying to create a device that will control a few independent RS485 lines using single USB port. My first idea was to use GL850G usb hub controller (4 downstream ports), 4x FT232R, 4x MAX485. I ...
2
votes
1answer
100 views

choosing the right Opto isolator?

In the process of developing an RDM Compatible DMX receiver board (using a ATMEGA328) and I have been fortunate enough to come across kimliv's most informative answer concerning such a board; DMX on ...
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2answers
612 views

STM32 RS485 connection

I want to interface stm32f0 with rs422 (half duplex and full duplex). What I'm not getting how to connect RE and DE signals to rs 232. From UART I'll be having RX, TX, VCC and GND pins which i need to ...
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3answers
704 views

Serial, RS232, Modbus, UART and TCP

I want clearly know this, Serial is protocol right? Then what is the Modbus? Is it under serial. And what are RS232 and RS485? What is UART and serial and UART same? What about TCP? TCP and serial ...
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1answer
84 views

The current needed for the RS-485 tranceiver?

The current consumption for the RS-485 IC is about 10 to 20 mA. However, if the two ends are shorted, the transciever can draw excessive current. So, I am trying to put PPTC device on it's VDD line ...
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1answer
128 views

2-wire RS485 Safe?

I am trying to assign a RS-485 option to the product I am designing. However, the physical constraint restricts me to use only 2 terminal block ports. So, I am forced to use two wire RS-485 ...
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1answer
137 views

Different wave form of Rs485

I have a device in aircraft (DEU). It has a output data to control a light ( diming control). In accordance with aircraft document this data is rs485. But i see a different form of wave in ...
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1answer
234 views

msp430 DMA UART for Modbus

I am using MSP430 UART with DMA transfer for sending Modbus packets. As a master at the end of packer I need to change my RS 485 transceiver direction line for reception. I am sending 10 bytes in ...
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1answer
56 views

IC Thermal shutdown recovery time

Many RS485 transceiver chips have a thermal shutdown when the junction exceeds 150C. Typically they switch back on once the junction temperature drops 15 degrees. How long does that typically take? ...
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2answers
929 views

What is the relationship between DMX and RS485? Are there any breaks in the protocol in relation to one another?

As far as the DMX is RS485 and at what points one moves away from the other? breaking the standard/protocol?
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1answer
434 views

Likely RS-485 color coding of three wires?

We received a piece of equipment (actually from an Italian manufacturer, if that gives a hint) which uses RS-485. So, as well as a power connection the devices have THREE WIRES (bare wires) coming ...
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116 views

For wrong termination resistor uses

Over 485-interface slaves are connected as multi drop, physically daisy chain. Those have built-in termination resistor, and the value is 120 ohm and no select switch for termination on/off. So it ...
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1answer
809 views

Serial Communication with rs232/485 and rj45

I am working a project where I want to connect and control, using Labview, TDK-Lambda Power Supply Process Vacuum Controller Ion Gauge (MODBUS interface) They both have rs232/rs485 capabilities, ...
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1answer
145 views

RS485 selectable termination device

I was given the task to make a new version of a board which have this little contraption for RS485 termination resistors: simulate this circuit – Schematic created using CircuitLab My ...
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2answers
342 views

RS-485 Modbus device to MCU

I have a device (an energy meter) that sends data via RS-485 (Modbus protocol). And I want to collect it with MCU. The important thing is that I'm trying to design a board and I want it to be ...
0
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1answer
373 views

Home automation on Cat5e again: is this a reasonable multidrop protocol?

Previously I have asked about running I2C over CAN PHY over Cat5e cables for my home automation project. Now after a round of money saving and experimenting, it seem to me that abusing RS485 chip ...
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1answer
297 views

UART Interrupt won't work

I have a problem when trying to test send and receive lines on RS485 communication, anyone know what may cause a problem here? It works without interrupt but with interrupt won't work. I am working on ...