Questions tagged [rs485]

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

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Assistance differentiating between RS485 transceivers (for use with Arduino slaves and master Pi)

I'm trying to spec out a project and get a shopping list together and am hoping to get some advice which parts to buy. The Pi will serve as the master and connect to a few arduino's at first, but I'd ...
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RS485 transmission activate PTT relay

I am trying to transfer serial data with a rs485 converter to a UHF/VHF transceiver. For the radio to transmit the data received, a TRANSMIT pin needs to be grounded. I am thinking to use the TX LINE ...
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Different types of RS485 circuits

I've seen in some schematics that the RX, TX, RE and DE pins are connected to VCC with a resistor. This is how the connection with the UART pins is made (see schematic below). In some schematics, ...
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Calculate RS422 signal to travel time from one side to another

I want to calculate the time take to transfer command from one uC side to another, this is the architecture: the Baudrate is 115200, the number of bits is 8. I would like to hear explain not just an ...
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Connecting 12 V RS485 appliance (soil sensor) to USB 5 V RS485 adaptor

I have a 12 V RS485 appliance that measures some soil resistance etc. It is a 7-in-one soil sensor, the 12 V version of the 5 V version shown in the link. I could not find a 12 V USB to RS485 adaptor ...
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Is it possible to use an RS232-USB cable (with an FT232RL chip) for RS485-USB communication?

I have a standard RS232 to USB cable found on Amazon. It does not work out of the box. This is what I expect since RS232 uses a ground reference and RS485 uses a differential between the two data ...
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Identify round RS485 connector

I'm going to get a solar inverter. It has a RS485 port on a round waterproof male connector: The diameter of the mating female connector shell seems to be about the same as a MC4, or 19mm. I'm ...
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UART to RS-485 communication between two Arduinos

I'm learning how to use a MAX485 or MAX487 IC to create a half-duplex RS-85 communication between two Arduino s. Each Arduino has an LED that turns ON/OFF by receiving a command from the other Arduino....
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MAX485ESA RS-485 doesn't work [closed]

I have my own PCB with MAX485ESA+ chip to use it as RS-485. I draw it similar to UART TTL to RS485 Two-way Converter. If I connect it with ROCK PI S UART3 and Single-phase Smart Power Meter, I can't ...
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What is SN75176 receiver pin drive current?

I am poor at understanding what datasheet symbols denote. Please help me decode what might be the drive current of receiver logic pin. Here is the link to datasheet: https://www.ti.com/lit/ds/symlink/...
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Flashing an ATMega microcontroller using a USB Connection

I'm trying to get into embedded system design and have been hung up on what hardware is required to use a USB connection to communicate with the microcontroller (and therefore, flash it). Here's what ...
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RS-485 possible ground loop

I am trying to develop a sensor network for a rainwater collection system. The setup consists of four "nodes" and a master, where each node has an ultrasonic distance sensor to measure the ...
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Which instructions do I use to be able to use UART directly on my STM32F107 microcontroller?

I've tried to figure this out on my own but after almost a week I'm still at more or less the same place where I started. So, I have an STM32F107 microcontroller on a board, which is linked to another ...
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Using CAN with Teensy 4.1 is better than using RS-485 which requires extra converter?

I am using Teensy 4.1 and need to communicate with motor driver which supports CAN and RS-485. In teeny4.1 CAN is supported yet it requires CAN transceiver whereas if I want to use RS-485 I need to ...
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Which data transfer speed (connection protocol) do I need?

I have 124 sensors that sense analog signals ranging from DC to 25 kHz. Analog data is converted to digital with a resolution of 16 bits. The ADC I am using is the AD7656 with a data rate of 250 kSPS, ...
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Isolated RS485 without specialized IC

I'm looking for replacement for ADM2587E. This is ADM2587E: Can I just use cheap, not isolated RS485 transceiver like MAX485 connected to microcontroller TX, RX, DE/_RE via optocouplers and power it ...
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Is this a legitimate RS485 wave shape?

I'm having issues but first of all I need to verify the other end of the communication line… there is a Moxa TCC-100 RS232-RS485 converter attached to the bus and I see this weird signal on the bus ...
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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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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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