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

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Echelon Smartserver rs485 relay control

I have bought Echelon's Smartserver, a lot of 4 channel relay boards and I want to connect them all together via a modbus network and for now to control the lights of the house. I have made all the ...
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43 views

Microcontroller - RS485 Reccomendation [on hold]

Is there a microcontroller with an embedded RS485 serial port, full- & half-duplex? I guess I could get a separate chip like a Maxim or Exar, but I'd like to make this as simple as possible. I ...
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17 views

Mod bus PC software

I would like to talk to an electricity meter I have which has a mod bus port and looking for some either relatively cheap or free PC software that provides the following functionality. Can talk to ...
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1answer
46 views

Multiple UART output sensors on one serial port

I would like to connect 4 UART output sensors to one serial port of my controller. The distance between sensors and controller will be about 10m. Initially I was thinking of using 485 as physical ...
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2answers
66 views

Long range sensor readings in a star network with Arduino

I'm planning a project that requires me to have around a dozen temperature and humidity sensors placed around the house and the yard. These would connect to a central Arduino in the house that would ...
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2answers
40 views

Termination resistor creating communication problem in RS485 MODBUS/TCP

In RS485 communication, what is the role of termination resisotor. Is it mandatory? I have been working on a project with MODBUS/TCP over RS485 where upto 32 slaves are there in some links, out of ...
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1answer
39 views

RS485 half duplex mode in full duplex IC

Datasheet link I am unsing full duplex RS485 feature IC. Please confirm below To use this IC in half duplex mode I need to short Pin B to pin z and Pin A to Pin Y. Since thease pins are internally ...
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1answer
29 views

Can I use SLIP on the same line as DMX?

I have a CAT 5 line with 12 DMX devices, each taking 4 channels. I also have a CAT 5 line with 8 microcontrollers (ex. Arduinos). These controllers need to send back data, and require error detection....
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3answers
184 views

What is the best practices of placing of termination resistor

Usually I placed the 120 Ohm termination resistor pads in the PCB. So I could place the resistor or not during the PCB assembly for different applications. However I suppose that the termination ...
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0answers
40 views

backplane for power etherner, rs232 amd rs485?

I’m trying to build a midterm system between a costly and highly custom VPX and a platform where each board interfaces with one another by cables. for example: imagine I have an off the shelf mini-itx ...
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1answer
47 views

Current requirement in RS485 Circuit

I am using ADM2482, Isolated RS-485 Transceivers. I need to calculate total max power needed to Drive this circuit. Specs are 1. Logic side voltage is 5V 2. bus side voltage is 3.3V 3. Speed 1 Mbps. ...
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1answer
90 views

Improving RS485 / UART slew rates

I'm trying to implement a half-duplex 1Mbps RS485 bus (1 master controlling ~8 motors). After facing occasional communication errors I've invested in a Saleae logic 4. The RS485 A/B lines probed ...
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3answers
52 views

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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1answer
63 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
88 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
296 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
65 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
63 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
89 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 pair,...
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1answer
43 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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1answer
82 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
94 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
36 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 part)....
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64 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
72 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
36 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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73 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
156 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
87 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
97 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
74 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
72 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
137 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
104 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
148 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
104 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
42 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
172 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
531 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
175 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
159 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
95 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
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1answer
105 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
711 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
879 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
91 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
135 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
146 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
243 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 ...