Questions tagged [rs485]
EIA RS-485 is a serial communication standard using differential signaling.
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I'm only able to read registers in groups [closed]
I'm integrating my power meter with the modbus interface with my smart home. I'm trying to read registries to provide data about current power usage, etc.
Is it normal that I'm only able to read ...
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UART as RS485 with Linux
I have been working on multiple projects of Embedded Linux from last 5 years but there is a small problem when I use UART.
I am using STM32MP13F with MYIR board. The UART is connected to half duplex ...
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Analyze this circuit: How to calculate corner frequency and simulate in Simetrix?
This is a RS485 communication circuit with power.
How do I calculate the high pass corner frequency of differential V1 coming to R1?
Does presence/absence of R8 change the corner frequency?
How to ...
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Simetrix not simulating a simple differential circuit
I want to give +-2.5V 1kHz waveform on one side to a bus powered by 15 volts and expect the AC waveform to appear at R1. I am trying to simulate in Simetrix, but I get this error shown in the image.
*...
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Can I receive RS485 data from two transmitters but not simultaneously?
I am receiving frequency over RS485 from two devices and my setup is as below
At any given time only one transmitter is powered on and other is not powered. Both the transmitters dont have ...
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24 Volt power over RS485
Can I modify and use this circuit from TI app note to power remote unit with 24volts DC and send RS485 data using same cable? What modifications should I do, my data rate is 38.4KBaud.
Here is the TI ...
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Trouble connecting RS485 turbidity sensor to a Raspberry Pi
I am trying to connect a Turbidity sensor that operates using Modbus to a Raspberry Pi. The sensor is an industrial-grade device and comes with the needed communication protocols (http://www.sonbus....
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What are pins 9 and 11 on this serial cable pinout?
I am fabricating a custom serial cable for a TEX Automation Systems Computer that is used in an HMI/PLC application. The manufacturer's required pinouts are:
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Selecting biasing resistor values for MAX3485
I created a schematic for the MAX3485 with the ESP32, but I have a question about the selection of biasing resistor(R39,R40) values. Some people use 4.7k, 10k, and 20k ohm resistors, but I'm unsure ...
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RS485 Communication Issue with ABB M4M 30 Modbus Using Waveshare RS485 CAN HAT on Raspberry Pi 5
I am using a Waveshare RS232/RS485 CAN HAT with a Raspberry Pi 5 running Raspberry Pi OS (Full, 64-bit) to connect to an ABB M4M 30 energy meter over Modbus RTU via Node-RED.
When I scan for devices ...
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Isolating only RS485 digital signals but not power
I am redesigning a battery powered system that communicates with other RS485 systems. The battery powered device provides the supply for the other external systems.
In the old design there was ...
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Individual switching power supplies for RS485
Is it a good practice to use individual switching power supplies to create galvanically isolated RS485 circuits? I know there are already isolated transceivers, but in my case, the power supplies are ...
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What is the best position for the TVS diode connected to the SN75176BP?
I am very unsure about the position of the TVS diodes that are to protect lines A and B of my IC SN75176BP. Should I place them before my 10R series resistor or after the resistors to my IC?
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Should CANbus transceiver have better noise immunity than RS485?
I have several boards connected by RS485 bus and they pick up some noise from motors. I've seen some digital edges received in non-driven state (between data packets) and, maybe occasional data ...
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Understanding differential buses: characteristic line impedance
Lately, I've been studying filters and differential buses, and there's still one detail that doesn't fully make sense to me — it's related to the line impedance and how it may affect the calculations.
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