Questions tagged [rs485]
EIA RS-485 is a serial communication standard using differential signaling.
403
questions
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Connecting 50 Arduino slave devices to a single master Raspberry PI
I am designing a automation system and need to have multiple slave devices(probabaly arduino UNO or NANO) communicating both ways with master device (Raspberry PI).
There is a server and database ...
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1answer
24 views
SC18IM700 operation (RS485 to UART to I2C)
I need to create a circuit to talk to a piece of equipment using the I2C bus. I'm on a PC that has an NI serial card with RS485 ports(I'm not sure of the model number off the top of my head). I ...
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2answers
41 views
RS485 Input Hysteresis
What is the meaning of Input Hysteresis in the context of a RS485 transceiver?
Thanks
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0answers
29 views
RS485 Trancievers: ADM2483 VS ISO15
i'm actually doing some hardware selection about RS485 trancievers. There are a lot of different suppliers, drivers, etc...
So, i've selected these two trancievers: ADM2483 from Analog Devices and ...
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26 views
How to light LEDs for serial data from Arduino over RS232 [closed]
I am a newbie to electronics and Arduino. I am in need of help. Any help will be greatly appreciated.
Here's is my problem statement
I want to light up 8 LEDs based on the serial data sent by arduino ...
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1answer
74 views
Glitching on UART RX line with RS485 transceiver
I have a custom PCB which has a RS485 transceiver chip interfaced to a Nordic microcontroller.
I essentially have a daisy-chained arrangement of RJ-11 ports which are carrying the RS485 A/B signals as ...
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0answers
57 views
How are DC offset square wave transmission waveforms generated?
The balanced serial transmission shown in the picture is similar to rs485 except that the square wave has a DC offset (e.g. 24VDC) with an alternating offset.
The transceiver chip "drives" ...
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1answer
67 views
RS422/RS485 termination and noise immunity
Consider a RS422/RS485 receiver like the AM26LV32 or the DS26LV32. It is used to receive the signal of incremental encoders with differential outputs. Assume that those are using drivers such as the ...
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1answer
52 views
Switch “On”/“Off” RS485 data lines
i'm doing some researches about how to close/open RS485 data line in my RS485 multi device bus.
I'm following this nice research-document: Link Here.
Basically i'm thinking how to solve this problem ...
4
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1answer
117 views
RS485 transceiver design: Bias, termination, filter and protection
For the realization of an RS485 transceiver, I came across the question: How can bias, termination, signal filter and protection be best implemented in one design?
In my case, one RS485 master (with ...
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3answers
53 views
Protocol with twisted pair for multiple switch control in a tree topology?
For an irrigation system, I'm interested in simple switches. My requirements:
Communication over copper wires, e.g. a twisted pair of cables
Nodes(switches) can be set in a tree topology, all sharing ...
0
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1answer
47 views
TVS diode for RS485
I'm studying the ISO1500 for an RS485 application. In particular, I'm looking for a TVS diode for bus protection. I've found that a common TVS diode used for RS-485 applications is the SM712 (like ...
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0answers
50 views
MAX487 can transmit but won't receive
I am trying to use a MAX487 chip to convert a regular UART signal to half-duplex RS485 signal and vice versa. I am using Atmega328PB as my micro controller. My circuit has no problem with transmission,...
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3answers
1k views
Could Cat5e be used for RS485 [duplicate]
I'm working on a project that will be using RS485 to communicate between a bunch of modules and a master controller. Low baud rate, 9600, but a decent distance, like a couple of hundred feet. I'm ...
1
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1answer
47 views
FT4232H: Configuring RI# as TXDEN Using FTProg
I am developing a device based around two FTDI FT4232H quad USB-to-Serial converters plugged into a Texas Instruments TUSB2046 USB hub controller. The serial outputs of each FT4232H channel goes to a ...
0
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1answer
61 views
ADM2483 or MAX485 Design: Modbus RS485 RTU bus in harsh environment
I'm currently out of ideas, i have a simple Wigoneer RS485 TTL interface (Sch link here) with MAX485 wired to my ESP32 based board, in my lab everything works like a charm with 1300 meters of CAT6 UTP ...
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1answer
43 views
Re : RS422 module from Aliexpress
Was planning to work on some long distance communications with RS485 / RS422 and I saw one of these boards on Aliexpress,Amazon etc..
Does anyone know what all those passive components could be?
Would ...
0
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1answer
48 views
Long Range (100m) USB(PC) to USB (microController USB module) Communication
I have a system that communicates between PIC32MX250F256D (USB module) and PC via USB (2 meters apart). And I need to increase the range of this communication to 100 meters. Due to typical 5m limit of ...
0
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1answer
66 views
Sniffing an RS-485 communication
I am trying to sniff a serial communication between two devices. One of them sends a command (6 bytes + 2 bytes CRC),
the other one responds (4 bytes + 2 bytes CRC). My computer monitors the exchange ...
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2answers
40 views
Effective differences between MAX485EESA+T and MAX485ESA+T?
Is anyone able to explain to me the effective difference between the MAX485EESA+T and the MAX485ESA+T?
The datasheet points out that is more tolerant of ESD discharge up to 15kV, nothing more.
Can ...
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1answer
19 views
RS-485 device to RS-232 adapter MUXing not working as expected
I have a RS-485 device that returns serial ASCII constantly. As the device might near very high voltage or electromagnetic areas, I need to ensure the RS-485 to RS-232 adapters I've been supplied with ...
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1answer
40 views
How to increase data through put of RS485 RTU?
I am using 20 sensor nodes, each has mpu9250 i2c, Arduino atmega328 MCU 8MHz and max485 chip in it,
each slave has a unique id program.
I have Arduino due as Modbus master with max485 chip,
I hope ...
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3answers
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Why single ended signal line is not immune to noise in RS232?
In single ended signal line the measurement is the difference between the signal and the ground. Isn't this way of calculation make it differential?
Almost all the resource I have read says that ...
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2answers
63 views
Wrong output using SN75HVD10 (RS485)
Designing a modbus master using a STM32F030CCT6 and a SN75HVD10 (3.3V).
This is the schematic
When i send the following message from the UART:
01 03 00 00 00 06 c5 c8
I see the following scopes (...
2
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1answer
65 views
Using CANbus cable for RS-485
I have a question regarding an application with a Modbus RTU network.
I would like to know if it's possible to use a CANbus cable instead of an RS-485 cable? Here is a picture of the cable:
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1answer
49 views
Is it possibile to use a CAN transceiver to send RS485 data?
Looking at the signal ranges I'm not sure if I can use a CAN transceiver (not controller!) to send data to a single RS485 device.
3
votes
1answer
38 views
Is there some kind of standard of modbus input register?
As the title said,
based on your experience, is there a such thing?
If no, which are the most commonly used?
for example in a sensor, the input registers as follows:
...
0
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1answer
62 views
USB to RS485: Can I connect A to Common Ground?
I bought a very cheap USB to RS485 dongle to connect to an experimental board of my own.
Specifications (may differ from the one I used but externally similar):
- Any baud rate from 1200 bps to 115 ...
0
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0answers
165 views
RS485 Pull-up, Pull-down and single termination resistor
Currently I use for Modbus RTU via RS485 with a shielded cable length of about 5 meters and a bitrate of 19.200 bit/s. Wired are 680 Ohm pull-up (A->+5V) and pull-down (B->GND) resistors near to the ...
0
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1answer
58 views
Can power supply be chained?
In my current project, I need to communicate and supply current to 4 sensor PCBs ("S1", "S2", "S3" and "S4") from a master PCB ("M1"). I will use RS-485 to communicate between PCBs, meaning I can ...
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0answers
33 views
Rs485 all nodes not communicating
I am Using a gateway etor-4 to convert Rs485 to ethernet and then provide data to Modicon 580 cpu.My slaves are tm221 controllers which are 22 in number.The problem is I can get only 5 nodes data ...
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2answers
131 views
Use half-duplex or full-duplex RS-485?
I have a master microcontroller that can control 4 slave microcontrollers. Each slave microcontroller is connected to 3 sensors.
The master microcontroller asks to retrieve the value of a specific ...
0
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3answers
112 views
Why lines A and B are HIGH when idle (rs485)
I'm using modbus RTU over RS485 for a project.
I use a RaspberryPI as master and Arduino Pro Mini as slaves.
My problem is the following :
I plug a sensors on the bus and it returs its value.
I plug ...
0
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1answer
42 views
How to wire up GSM Modem(DCE) With MAX485
I am trying yo figure out how to directly connect a GSM modem (say SIM800) with a MAX485 . The purpose of this is to make an RS485 GSM Modem. I am struggling how to wire it up, do i wire the CTS of ...
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0answers
12 views
XPort Edge (web manager) access denied with default credentials
I have the Xport EDGE connected and powered using the evaluation board.
I'm trying to use an XPort EDGE as a means of connecting an embedded device to the internet. It uses RS485 (That's the ...
0
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1answer
49 views
GSM Module + RS485 transceiver possible?
I was wondering if someone could confirm if it is feasible to interface a GSM module for example SIM900, SIM900, Quectel's M95 or Neoway's N10 , maybe if we use the RS232 interface with HW the flow ...
0
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1answer
60 views
RS485 communication between Arduino
I want to transfer data (only numeric values) between Arduino Nano and Arduino Mega 2560. I tried with my own code and tried with several libraries also.
Arduino Nano code
...
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1answer
85 views
Noisy RS485 signal with MAX13487E and Raspberry Pi
I am trying to use the MAX13487E RS485 transreceiver with a Raspberry Pi 3 B+. I chose this chip specifically because it does not require a RTS signal, which is complicated to setup on the PI. My ...
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0answers
152 views
Replacing the physical layer of MIL-STD-1553 with RS-485
I've been reading about MIL-STD-1553 buses, which very briefly are
multidrop
Manchester-encoded
1 Mbit/sec
32-station: a single "bus controller" master and multiple "bus terminals" slaves which speak ...
3
votes
1answer
223 views
Decoding an unknown serial bitstream that does not fit 8-N-1
I am looking at an RS-485 signal using a scope and an analyzer (saleae). This is running a mystery bus (see below for more information). I would like to know how to fix my frame errors. I can't begin ...
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2answers
145 views
RS485 Common Ground: Common Voltage or Common Wire or Both?
RS485 connection needs a common ground, but I am very fuzzy about how that works over longer distances and more complex systems.
When the transmitter and receiver are about 1000m apart, there will be ...
0
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4answers
385 views
RS422, RS485 Termination Resistors
While going through this youtube video from TI about the RS232, RS422, RS485 differences. One thing that don't understand clearly is following slide from this video.
The blue resistors that I marked ...
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0answers
77 views
RS485 - Comunication lost during EFT IEC 61000-4-4
I'm having throubles with communication over RS485 in harsh industrial environment.
We perform test in EMC lab, acording IEC 61000-4-4 = Fast transient (also known as Burst).
We used burst generator ...
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2answers
75 views
1-channel GPIO from industrial PC over RS232 port
I am ordering a computer based on 4x4-R1000V motherboard (Ryzen Embedded, https://www.asrockind.com/overview.asp?Model=4X4-R1000V) for an industrial application.
I need a 1-channel GPIO (0 for zero, >...
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2answers
79 views
Please help me understand modbus communications
I'm just starting out with understanding how modbus works over a rs485 protocol.
I've received a communication protocol document from a company that makes solar inverters.
I want to send a command ...
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1answer
253 views
Isolated Modbus (RS485) ground and UART noise
I build an isolated RS485 (Modbus) interface board for a sensor. I use ADM2682 as transceiver and VAQE6W-Q24-S12-D as isolated DC-DC converter. All is managed my a STM32L412.
There is 2 interesting ...
0
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1answer
61 views
How would I connect an HC-06 bluetooth module to an SN75176A RS-485/422 transceiver?
I am trying to fashion a small module that would allow me to connect to an RS-485 system via Bluetooth. I have found that the potentially cheapest solution would involve an HC-06 TTL Bluetooth ...
2
votes
1answer
56 views
Modbus: Sensors timed out when plugging another sensor
I have created an hydroponic system using modbus to communicate between a RaspberryPI server and plug&play arduino sensors. It works but as soon as I plug a sensor on the bus (physically), all the ...
0
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1answer
47 views
Questions on connecting and using the RS485 MAX14783E transirver
Task:
Using Arduino UNO, obtain various parameters from the ABB B21 112-200 electric energy meter, as well as send settings to it.
This meter has an RS485 interface (ModBus RTU) with terminals A, B, ...
0
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2answers
61 views
How to connect a few shields correctly?
There are several shields on my PCB: shield on CAN-bus, on RS485, on Ethernet, on ENCODER motor signals.
How do I correctly connect all these shields? If I use the star topology, which filters should ...
