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

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1answer
57 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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0answers
38 views

Understanding modbus library function for arduino

I have a device with which I want to communicate and read it's data. It's data starts at 3000H. I am making use of Juan Bester modbus library for arduino. Regarding the circuit, everything is sorted ...
3
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1answer
61 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
73 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 ...
1
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1answer
52 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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2answers
52 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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0answers
5 views

Modbus master arduino code is throwing weird errors on upload [migrated]

I am using the following https://code.google.com/p/simple-modbus/ arduino master library code. In order to communicate with my industrial drive. All seems right but I am getting some weird errors. I ...
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16 views

Max485 Arduino Uno Not transmitting

I am using an arduino uno 2x Max485ecpa+ 2x 100ohm resistors and an arduino micro (leonardo) and whenever i try to transmit something from the uno to the micro through the max485's nothing happens. ...
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0answers
67 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 ...
0
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1answer
59 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 ...
0
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1answer
56 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 ...
0
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1answer
68 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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0answers
31 views

Power from Modbus / RS485

Totally new to Modbus, I need some help. I have a sensor that communicates over Foundation Fieldbus and draws it's power from the bus. I would like to make an adapter to connect it to a RS485 based ...
2
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1answer
38 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 ...
0
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1answer
78 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 ...
0
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2answers
43 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
228 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
80 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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0answers
67 views

Send/receive data using RS-485 to USB adapter

Familiar with RS-232 but new to RS-485. I would like to both view what is being sent from a host over RS-485 and also send RS-485 data from a PC to a slave device. If I order the following USB to ...
0
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1answer
99 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 ...
2
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2answers
75 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
82 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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1answer
301 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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2answers
258 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 ...
0
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1answer
59 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
103 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
92 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
180 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
52 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
444 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
253 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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0answers
96 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 ...
0
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1answer
527 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, ...
2
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1answer
104 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
268 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
252 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 ...
0
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1answer
225 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 ...
0
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1answer
73 views

Is it safer to use multiple RS-485 point to point connections compared to a daisy chain?

When wiring multiple RS485 slaves to a master equipped with a RS232/RS422/RS485 interface*: is it safer to wire multiple point to point connections from the hub with their own termination resistor, ...
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3answers
1k views

Can I an RS422 interface to Arduino's serial pins?

I have a custom-designed circuit that communicates to and from the external world through an RS422 interface. I wish to communicate with it with an Arduino, preferably UNO. The RS422, much like the ...
2
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2answers
173 views

Using RS-485 receiver with RS-422 signals

I have a controller that has a RS-422 output, can I use it to only send data to another device that has RS-485? please explain Thank You!
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3answers
901 views

Correctly using RE and DE with RS485

I'm trying to build a RS-485 project using MAX485's. However, I'm having trouble finding out how to correctly use the RE and DE pins. Some PDF's and websites say that RE and DE should be tied together ...
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2answers
111 views

Looking for a long-distance (~1km) physical layer

First of all, I have to say my knowledge on how networks work physically is limited. I am working on a project to interconnect farming equipment over fairly long distances, at a maximum of 1km, more ...
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2answers
530 views

PIC24F UART Rx Interrupt not firing

I am currently trying to write code for a 48 channel DMX controlled dimmer using a PIC24FJ32GA002. Using a scope I have confirmed that there is a DMX signal reaching the Rx pin of the UART which has ...
1
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4answers
271 views

What kind of component would I need to put a break in a RS-485 bus?

I'd like to have some kind of electronically controlled switch (transistor, relay, solid-state relay, etc) that acts as a break in a RS-485 bus. The effect I would like is to optionally split the bus ...
0
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1answer
119 views

rs485 loading problem

I've one system with rs485 with max485 chip with microcontroller (pin 2& 3 r connected to gpio).To access that system I've made one other system with ilx485 chip. Pins 2 & 3 of these are ...
0
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1answer
270 views

Wiring RS485/422 to RS232 converter to a given device pins [closed]

I'm trying to establish a full-duplex and then a half duplex communication and need to wire a device output to an RS485/422 to RS232 converter. Here is the device output pins for full and half ...
2
votes
1answer
840 views

Looking at a RS485 signal with an ocilloscope

Is it possible to view a RS 485 diffential signal using a Rigol DS1102E 100MHz Digital Oscilloscope, Dual Analog Channels, 1 GSa/s Sampling, USB Storage? I can see a signal that looks more like ...
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2answers
733 views

RS-485 isolation required?

I would like to confirm my understanding. Suppose I'm want to have two battery-powered MCUs inside an (unmanned) aircraft communicate with each other via RS-485. If those MCUs are powered from the ...
0
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1answer
685 views

Connection problem with RS485 system on PC with RS232 port

I am developing a system in which I have to integrate hardware. I am from computer background, so I don't have much knowledge about hardware systems. The issue is I have to integrate with London ...
5
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1answer
307 views

DMX512 packet issue (no break?)

I'm not sure if I'm reading this wrong or something, but this is a trace of the DMX packet that's coming from my USB-RS485 module then being converter to UART logic levels for my microcontroller. ...