Questions tagged [rs485]

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

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4answers
820 views

Why common-mode choke on differential-signal serial lines?

I have 2 questions: Why using a common-mode choke on serial communication lines (like CAN, RS485) if the signal is differential? Wouldn't the common-mode noise simply be cancelled in the receiver? I ...
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1answer
20 views

Half duplex connection with a full duplex cevice

I have a sensor that I want to use with Modbus RTU and am not sure if I can use half duplex or if I need to use full duplex. I would also like to get some suggestions how to read from it with my ...
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1answer
58 views

Cable simplification by replacing them with wireless [closed]

I have a system made of two subsystems: a computer in a cabinet a sliding robotic arm connected to the cabinet. The sliding arm is powered and gets its commands through cables from the cabinet. I ...
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0answers
56 views

Disabling receive / transmit on half duplex RS485 module

I have been unable to find a schematic for the half duplex rs485 modules that I am using. However, to ensure proper functioning for the design I’m using with only using one way data, it was ...
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2answers
66 views

Powering isolated RS485 over CAT6

I'm creating an RS485 network where data and power will be transmitted over a 23AWG CAT6 U/FTP cable. Two twisted pair conductors will be 36V and GND respectively, another twisted pair will carry the ...
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3answers
129 views

Configuring SPI circuit design for use in 485 transceiver for long range data transmission (50 meters plus)

So quickly getting out of things I have previously done however trying to send SPI controller signals across long ranges using either 18 AWG cable or based on all the recommendations we have been ...
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1answer
39 views

Can you integrate an LVDS with a common RS485 if the RS485 is used as a discrete and not a digital serial signal? [closed]

Is the LVDS compatible with an RS485 signal? Can i integrate 2 systems in this way?
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1answer
58 views

What's the correct pinout for Half Duplex RS-485 in an RJ-45 connector?

I'm working on a project that involves some long-distance communication using RS-485 and MAX485 and MAX3485 ICs. My project features custom PCBs (essentially Arduino/Teensy Shields) which react and ...
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2answers
96 views

Differential Signaling and RS485 difference?

I am trying to wrap my head around the difference between differential signaling (mainly LVDS and LvPECL) and RS-485. All seem like differential signaling for serial communications. From the TI Page, ...
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1answer
34 views

SP3485EN current consumption

I would like to size my source regulator for a circuit which contains the RS485 to UART bridge SP3485EN. How may I know the current consumption of the SP3485EN? Does it depend on the load? If it is, ...
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1answer
39 views

What size resistors for PD for RS485 pullup?

I have an RS485 circuit running over CAT6 cable. I have a 120r resister between the two data lines at each end, and at one end a 680r pulldown to ground on the -ve and want to put a 680r pullup to 5v ...
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2answers
82 views

Best practice to wire RS485 2 wire device to RS485 4 wire device

I am currently trying to communicate with a modbus slave through a RS485/Ethernet converter. The slave device is RS485 2 wire, and the converter is RS485 4 wire. As of now, I wired both Tx+ and Rx+ to ...
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1answer
79 views

RS485 Reverse Engineering

I'm reversing a RS485 comunication. I have purchased a logical analyzer for reversing and sniffing the data packets. But i have a problem, don't knowing the exactly comunication parameters i can't &...
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2answers
57 views

Help to discover if it is a serial protocol or faulty devices

This is my first question. I have a rs485 anemometer and a rs485 windvane purcased in Amazon from Cryfokt and Adsire-R vendors. I spent time trying to make them work so return time has expired. They ...
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3answers
122 views

Good idea to use UART in half-duplex mode when using RS485 transceiver?

Most 2-wire RS485 implementations I have seen use both UART RX and TX pins which works of course. And I have done so. But I was wondering whether using UART in half-duplex mode is a good alternative ...
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0answers
92 views

Problem with USB to RS485 design (CH340B linux)

We designed USB to rs485 converter, which is working fine. We designed now software, which is transmitting really lot of data. Baud is 19200. We are now facing problems, that converter stops receiving/...
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1answer
95 views

Help in deciding between RS485 or CAN [closed]

PROBLEM I'm building a robot control board to attach to a Raspberry Pi as an hobby. I like to have specialized boards for various functions, and I'm exploring solutions for the communication bus. In ...
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2answers
50 views

RS485 different voltages

Please note that I'm a beginner in electronic... Hello, I've got myself some RS485 modules to test with Arduino and i managed to get them working in half-duplex. From this post I've seen that for ...
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0answers
36 views

Why my pic18f458 send 0x00 by uart after recived a byte from pc?

I wish to know is you can help. I'm trying to comunicate by rs485 a pic18f458 and my PC, like it show the image. This is what I want to happen: Send a byte from PC to microcontroller. The ...
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0answers
44 views

DMA Normal Mode And HAL_UART_TxCpltCallback

I am using UART with DMA on stm32f4xx. I am trying to use RS485 interface. When I use the HAL_UART_TxCpltCallback, callback I get hardfault in my proccess. How can I check transfer completed without ...
0
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1answer
55 views

SN75176 with 3.3V

Can I connect the SN75176 RS485 transceiver with a 3.3V microcontroller? The datasheet says that it must be powered with 5V and all inputs / outputs are TTL, but I'm not sure since the minimum high ...
3
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4answers
578 views

RS-485 full-duplex driver termination, where do I place the terminator?

Where are the right places to put termination resistors in RS-485 networks? Specifically in full-duplex networks, I see app notes either use the termination at the driver node (Maxim (Page 15), TI (...
0
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1answer
37 views

How to isolate 5V supply for RS485 (low profile & cheap)

I'm building a RS485 transceiver module and I wanted to isolate the power and data. I am going for a solution wiht a digital isolator (such as TI ISO7721DR) and a power isolator followed by a RS485 ...
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2answers
68 views

Reverse Engineering RS-485 Signals - Floating Issue

I'm currently trying to reverse engineer RS-485 signals, see waveforms below. As you can see, Signal 1 (Yellow) and Signal 3 (Purple) are a differential pair and seem to be floating. Here's a closeup ...
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3answers
95 views

RS485 medium range communication

Hi, i don’t know if this is the right place to ask but i’m out of ideas so if i need to delete this please tell me. Also, please note that i have little to no experience in electronic so if i make a ...
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1answer
66 views

RS485 multidrop to UART

I'm trying to do a multi-drop setup where I have two RS485 devices(with MAX13430) daisy chained without termination resistors(for now) as they're pretty close(few cm apart) and at pretty low speed (...
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1answer
28 views

Inverting Pairs in Full Duplex RS485

The following is the Full Duplex configuration for a Maxim 3292 RS-485 transceiver module. It is possible to invert the polarity of the pairs, lets say, exchange AB by BA and ZY by YZ at the Master ...
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2answers
77 views

UART and DMA data size

I want to work with the RS485 interface with UART protocole, but I need to choose which method useful for me. I want to use DMA but the data length is not constant, how can I manage the DMA with non ...
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0answers
25 views

RS-485 Modbus keeps sending set timeouts. Is it normal?

I try to monitor RS-485 communication between Toyo motor drivers and an IPC control program. I monitor with a third-party software Device monitoring studio. The program is written by us. However, I ...
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1answer
34 views

What is the likely power consumption for the SP3070EEN RS422 Transceiver under normal operating conditions?

I am designing with the SP3070EEN. SP3070 Datasheet I've tried to calculate the power consumption that this IC is likely to use when transmitting under normal conditions. I ended up with ...
4
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2answers
123 views

RS-485 Connecting 100 devices - Avoid GND Loop

I'm new to community and it's my first question, so please forgive me for mistakes I could do referring to adding pictures and descriptions. I plan to use 100 devices and connect them via RS-485 in ...
0
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1answer
25 views

RS485 UART Rx Receive Event Handler not fired for all Tx Commands sent [closed]

I am using (1)Azure Sphere MT3620 Starter Kit and (2)RS485 CLICK 5V and (3)Geovan Board Here is the setup (I don't have latest picture, so #2 is swapped to first slot in the MT3620) My MT3620 is ...
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2answers
102 views

Termination resistors using bipolar transistors for RS-485?

I am planning to use RS-485 on a network and I do not have too much experience on the standard but I understand that termination resistance must be provided for considerable lengths and transmission ...
0
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3answers
168 views

Cable selection and wiring for RS485 communication

I'm designing a sensor system where each sensor communicates via RS485 MODBUS in a high-density environment. Each line consists of 18 sensors which then goes to a gateway (Elfin EE11) that converts ...
0
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0answers
58 views

Using MAX485 with a full duplex device

I have MAX485 board. MAX485 is a half duplex 485 IC. There are A&B pins. The device which i should communicate it has the following pin diagram. I think this is full-duplex interface. Can i ...
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0answers
60 views

UART Blocking Mode and Non-Blocking Mode

I want to using RS485 communication between two or more device using stm32 + tranceivers, I need to request-response type communication so RS485 bus will have many data. Which one would make sense to ...
0
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1answer
78 views

RS485 Receiving Data Corruption

This was my first topic, RS485 Tutorial Issue. I referanced because of the schematics. I solved the problem in above topic, I forgot to pin settings for DE and RE pins. I have a different problem now. ...
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1answer
147 views

RS485 Tutorial Issue

I have two device ( ISL83485 + STM32), and they connected on RS485 line. I want to send some UART signal to RS485 line with a tranceiver. I am using ISL83485 tranceiver for this purpose, I am using ...
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2answers
102 views

ESD protection on an isolated circuit

I'm currently working on an RS485 DMX circuit and am thinking about proper protective measures. I've oriented myself on this question. I understand that galvanic isolation does not equal ESD ...
2
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1answer
235 views

USB to RS485 converter on Linux [closed]

I have a USB to RS485 converter: It has a CH341 chip, that is all I know about it. When I plug it in, I can see that it is bound to port ttyUSB0. I want to be able to send and receive bytes from PC (...
2
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0answers
29 views

Choose between Profibus PA and DP

I currently try to understand a new technology: Profibus, until now I worked with HART, with which I also had some struggle in the begging but now it's clear. I try to understand why in a factory is ...
1
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1answer
57 views

Overvoltage protection RS485 inputs

The finished apparatus is supplied with 48V nominal ac (37V to 57V), and now I'm looking to design it so that it isn't destroyed if a technician accidentally connects the supply 48V +/- to the RS485 ...
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1answer
58 views

differential input overvoltage protection

some suggestions to protect an RS485 from differential input overvoltage? I want protect the transceiver RS485 if the differential input voltage is below -7V or above +12V. Someone does anyone know ...
0
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1answer
83 views

protect RS485 from PoE

I have a board with two RJ45 connectors. One is used for an Ethernet port and the other one is for a RS485. The Ethernet is for Power over Ethernet. What are some suggestions to protect the RS485 port ...
0
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1answer
68 views

MAX3485 pull-up pull-down resistors

I want to use the following MAX3485 chip: https://datasheet.lcsc.com/szlcsc/2006181334_UMW-Youtai-Semiconductor-Co-Ltd-MAX3485ESA_C668204.pdf I do not speak any chinese, but my question is more in a ...
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3answers
973 views

Is it OK to use RS485 with separate wires for each device?

I know common use of RS485 is top wiring diagram. But in my project we need to use RS485 for extend range and reliability connection but connection will be bottom wiring diagram. Can I use a single ...
0
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1answer
121 views

Using digital and analog signals in the same cable

I am working on a project with 3 PCB : PCB1 is the master, it communicates with two slaves, PCB2 and PCB3. PCB1 is powered by a battery and it redirects the supply to PCB2 and PCB3. Each PCB includes ...
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0answers
457 views

How to interface a RPi Pico to DMX / RDM

Years ago, I was looking at creating a stage DMX controller using AVR. Time moved on and the Raspberry Pi Pico has now been released. I'd like to revisit the project using a Raspberry Pi Pico, which ...
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2answers
127 views

10m wired connection: I2C Repeater or RS485 [closed]

I need a wired connection between one Master and several (5-10) slave devices. I've considered UART, SPI, I2C, RS232 and RS485. In the end, I've narrowed down the options to I2C with a repeater or ...
0
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0answers
39 views

Using an Ethernet Phy and XFMR instead of RS422

We've been using a quad RS485 setup for some time. No problems. Now we'd like to increase the speed over what we can get away with on RS485 with the micro we're using. Essentially, we've been ...

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