All Questions
Tagged with rs485 serial-bus
23
questions
0
votes
0
answers
312
views
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/...
- 7,120
6
votes
8
answers
2k
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 ...
- 285
3
votes
2
answers
1k
views
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 ...
- 8,536
8
votes
4
answers
3k
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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 ...
- 83
0
votes
1
answer
520
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 ...
- 1,427
4
votes
1
answer
5k
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 (...
- 287
0
votes
2
answers
608
views
Terminating resistor considerations for half-duplex RS-485 over 80-200 m cable at 115 kbps
I'm designing a system where we are communicating with a device (ultrasonic anemometer) which is at the end of a cable which could vary between 80-200m.
The sensor communicates via RS-485 half-duplex. ...
0
votes
1
answer
137
views
Bus communication scheme for large number of devices (255+ nodes)?
I'm trying to figure out the feasibility of setting up some type of differential bus communication for up to 400 devices outdoors. The main constraints are mainly power consumption, complexity, wire ...
1
vote
0
answers
186
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" ...
- 3,282
-1
votes
3
answers
134
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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 ...
- 99
1
vote
2
answers
665
views
Reverse-engineering RS485/Mechatrolink-II front-end design
I'm trying to reverse-engineer Mechatrolink-II front-end circuitry. Its physical layer is simple RS485 (with isolation transformer) running at ~10Mbps.
Here is the schematic I obtained from the PCB of ...
- 128
2
votes
1
answer
5k
views
RS422 and RS485; full-duplex or half-duplex?
I have extensively used RS232 transceivers in many projects and have fairly good understanding of UART communication using RS232 transceivers. MAX232 and MAX3232.
Now I have to build my understanding ...
- 1,479
1
vote
3
answers
2k
views
What is the difference between a multiplexed bus and a multi-master bus
The jargon of terms in bus architecture literature is half the difficulty in understanding it. At some places the term 'multiplexed' bus is used while at some other places 'multi-master' bus is used. ...
- 1,479
0
votes
2
answers
1k
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RS485 vs RS232 similarity vs differences
I have used UART RS232 communication between MCUs extensively. Now I need to interface my STM32F407 MCU over RS485 bus with with devices. I have understood few things about RS485 but not-clear about ...
- 907
2
votes
2
answers
133
views
How to select the most appropriate (serial) bus for controller?
In the context of a robotic project where different 'payloads' and/or robotics arms (end-deflector) should be mated mechanically with power, data and control connections support, I would like to ...
- 21