Questions tagged [rs485]

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

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How does this RS485 transceiver work?

I'm attempting to communicate with an RS485 network with a raspberry pi pico, and I found a "hat" which includes a couple SP3485 transceivers, along with the supporting TVS diodes, etc. The ...
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RS-485 Network Topology with Backbone and Daisy-Chain Stubs [closed]

I am designing a RS-485 network and would like to know whether the configuration below would work. The transceiver I am using is the Maxim MAX485, with the master ad slaves hardwired to always ...
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CAT6 for both RS485 and CAN in same cable

I have two devices which need to talk to two controllers about 60m away in the garden.One uses RS485 and one uses CAN. I have to run armoured CAT6 for this and wondering if I can use the same run for ...
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MCU working at 3.3V and RS485 driver at 5V - how does this circuit work?

I was looking for a "quick and dirty" solution in order to work with MAX487 (5V) and my ESP32 MCU. I know that Maxim integrated produces the MAX3485 and MAX3483 that are specifically ...
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Connect multiple devices with USB

Consider a setup with 1 "server" device and 4 "client" devices (all are SBCs with Ubuntu installed). I would like to connect the 4 clients to the server, using USB/serial. Ethernet ...
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How to test TF02 pro (rs485) LIDAR sensor

I have a tf02 Luna pro (RS485 version). I would like to test whether this sensor works or not. There are 2 possible test I can think of I can do. First is to use an RS485 to USB converter I had lying ...
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Max485 Overheat

All - I know variations of this have been asked, but I couldn't find one that seemed to address my application or situation and apologize in advance for any overlap I have a board design used to ...
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RS-485 bus with multiple clusters of devices?

I need to connect five stations via RS-485 MODBUS RTU. The stations are 1-2 m apart, and each one has three RS-485 devices within fairly close proximity to each other. The distance to the bus master ...
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Micro USB and RS485 Compatibility

I am looking into understanding micro usb better and seem to be missing something apparently obvious different about the difference between micro usb and rs485. From looking online like here, the ...
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Connecting a radio device with controller (+ power supply) [closed]

I have a min knowledge in electronics, so I am sorry if my questions are stupid for you. I am studying how I can connect a radio device with a controller. The radio device is a transmitter/receiver or ...
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Why do we need FPGA and not microcontroller to implement Bitbus protocol?

I need to design a board with a Bitbus protocol master to interface with other slave devices and was searching for options. All I get is Bitbus protocol IP for FPGAs. Why can't we implement Bitbus ...
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Modbus over RS485 - no response from device

I am trying to connect to Epever Tracer AN Solar Charge controller from ESP32 using below Max485 module but I can't get any repsonse from device. I was trying to use exactly the same setup mentioned ...
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RS-485 connection to motor encoder

I'm using a homebrew encoder based on two A3144 hall sensors (logic, open collector) to control motor rotation. It's connected to the MCU via 2 metres of fancy double-shielded cable with 1K pull-up ...
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Tiva C microcontroller to DYNAMIXEL servo (UART to RS485)

I am really struggling to establish communication between Tiva C TM4C123GH6PM microcontroller to use Dynamixel servo. Here is the circuit where MAX485 converts UART TTL signal to RS485. This servo has ...
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Audio, DC-power and RS-485 over Ethernet, which pairs?

I'm looking for a solution to connect small Full HD cameras that normally have a very convoluted breakout-cable, over a standard Cat6A Ethernet cable. The camera's video and audio-out go over a ...
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Fault Protected RS485 circuit

I am designing a product for use in the industry and it needs to include a fault protected RS485 interface. In the industry the most normal voltage for the power supplies in the machinery is 24V, but ...
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RS-485 communication with slave microcontrollers driving addressable LEDs?

I am trying to figure out how to achieve the master-slave configuration shown below. The aim is to individually address an array of 150mA LEDs, driven by the IS31FL3265A PWM driver. For this specific ...
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Protection of short from 48 V to RS 485 data line

In a cable I carry a 48 Vdc supply line and a RS 485 differential signal pair from a SN75176A transceiver. The 48 Vdc line is protected by a 5 A fuse, and the SN75176A transceiver inputs and outputs ...
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LED on RS485 bus

I would like to insert two LEDs on an RS485 bus (i.e. on the RX and TX side) that flash when there is a communication passage. I have a 24V power supply, and I could use op-amps (like the LM358) or ...
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Troubleshooting RS485 UART comms on BeagleBone black or AI

I wrote the following code to trouble shouting the RS485 communication aspect of my firmware. I use either a Beaglebone black or AI equipped with the cape COMMS 2 (which as a built-in A/B RS485 ...
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Is it advisable to make communication re attempts in modbus?

In my system, I know that the approximate response time between master-slave is 10ms, if the slave does not receive communication during those 10ms then it detects an error and the motors turn off. Is ...
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Maxim MAX3485ESA+T vs SP3485EN-L/TR

I have a question about the MAX3485ESA+T RS485 Transceiver. I ordered a PCB with a MAX3485ESA+T and the project doesn't work. The previous design was with a SP3485EN-L/TR and it worked well, but I had ...
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How to identify Modbus device speed rate?

In particular how to identify it without causing device misbehaving. Either new device is being connected, and master has no idea what baud rate the device is configured with (assume it knows about 8/...
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Atmega328 and max485 schematic problem

i'm making atmega328 and max485esa in one pcb. first build using an external 5v dc source and without any problems. the code works fine, the ws2812 led on the receiver module can light up. the second ...
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Can MAX485 be connected to SN75176 for RS485 communication?

In one side I have an SN75176 and the other side is MAX485. Can both be connected for RS485 communication?
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Increasing the number of MAX485 nodes

I have two ports available to connect the RS485 dongle while a single RS485 dongle has a maximum of 32 node. I have 400 plus slaves to connect with RS485 so I want to know how can I connect multiple ...
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Testing the reliability of RS485

I have implemented an RS485 communication with CRC data validation and some algorithms to manage errors when the data received is lossy. How can I test the packet loss during RS485 communication? Is ...
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The origin of the "cable length - data rate" graph in the RS-485

In several RS-485 application notes one can find a graph that describes the relationship between data rate and cable length, like this one: But not a single document describes how to calculate it on ...
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How to create an RS485-compatible line driver with an adjustable slew rate?

I need to make an RS485 compatible line driver, capable of 12Mbit/s with fast slew rate, but with the capability to reduce the slew rate to about 50ns rise/fall time when operating at lower bitrates. ...
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7 answers
738 views

How does the current of RS485 signals return from the receiver to the sender?

I am planning a system consisting of 1 master device which is connected to 19 slave devices using RS485 transceivers. Also, all devices are powered by 1 PSU. A simplified schematic is shown below. As ...
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RS485 MODBUS ARDUINO: Print multiple response data frame from soil sensor

Hi everyone. I'm guiding myself from tutorial https://how2electronics.com/measure-soil-nutrient-using-arduino-soil-npk-sensor/ I'm using... Hardware components: RS485 Arduino uno Charger 9V (Only for ...
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Alternatives to CAN for multi-master transmission

As usual these days I'm fighting against component shortage. As in completely redesigning boards since they give us lead times in the 2023 years. At the moment I have this product line where the ...
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How to connect a slave device to an RS-485 network without a signal ground reference terminal?

I want to connect a flow meter and a variable frequency drive (VFD) to the same modbus network but the absence of a signal ground reference terminal on the flow meter is causing me some confusion with ...
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Rs485 A & B Labels being used inconsistently

I would like to know if there is an official standard with regards to rs-485 terminals being labelled A & B. I have always believed: A=> + (positive) and B=> - (negative) however, I have ...
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Can MAX485 TTL-to-RS-485 module be used as UART-to-RS485 module?

I'm trying to make a bridge from Modbus til Home Assistant using an ESP8266 (as outlined here), which uses an UART-to-RS485 module. I have this MAX485 TTL to RS-485 Interface Module. I'm not competent ...
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Can I send PWM through 1 meter cable?

I am working on a project where I need to drive two LEDs on a PCB (= PCB_LED) which is 1 meter away from another PCB (= PCB_MCU). The PCB_MCU includes a microcontroller with two LED drivers. Each LED ...
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Need Help Connecting Arduino to PC via RS485 with Max485 breakout board

I am currently attempting to connect an arduino to a PC via the RS485 communication protocol using a max485 to convert the RS485 to serial. It does not however appear to be receiving any data at all. ...
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Want to use SPI sensor in RS485 modbus

I want to use multiple ICM20948 over SPI to RS485 with esp32 . is there anyway to do it and also is there have any other IMU which support rs485?
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Modbus Vs CANopen - Which one should I choose?

Modbus Vs CANopen - Which one should I choose if I want: Broadcast to all units Talk to specific units Robust Send lots of data Implement for embedded systems Easy to use Using in new projects with ...
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RS485 Protocol Reverse Engineering & Replay Challenges

I'm trying to reverse engineer the RS485 protocol used by my home heater/AC. This protocol handles communications between the wired remote control (WRC)/thermostat and the main heater/ac indoor unit (...
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MAX485 slave nodes issues, using MAX487 for RS485 slave nodes?

I've designed some ATMEGA328p based nodes using MAX485, this is the base schematic: The only difference from the schematic is that the A-B biasing resistors (R13-R12) value is 680ohm and the R12 is ...
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How to test for PCB ground being pulled up to 2V when connected to RS485

I am currently trying to find an easy way test to diagnose a problem on some of our PCBs where the ground of the PCB is being pulled up to 2V's. The Board Simple modular RS485 sensor board. The main ...
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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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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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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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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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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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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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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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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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