All Questions
15
questions
1
vote
1
answer
181
views
Noise during RS-485 operation
I have a switching step-down power supply SCM1301A, from which the entire circuit is powered, namely the microcontroller, op-amp, RS-485. I digitize the signal coming from the microwave module, having ...
- 41
1
vote
2
answers
453
views
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 ...
- 427
0
votes
1
answer
662
views
RS-485, 5Vdc and 24Vdc over a single Ethernet cable
I recently started to work on a project that involves motor drivers and microcontrollers in a network topology. This is rather a theoretical question, just something that I was thinking about. The ...
- 287
0
votes
2
answers
83
views
485 does not work some times
in fact i have several boards like Analog barrier, digital barrier, uart barrier and power control.
they are connected to together by RS485.
but some times when some of 485 don't work of the RX led ...
2
votes
3
answers
3k
views
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 ...
- 71
1
vote
1
answer
663
views
RS485 Eye diagram - does it look good?
I got a new diff probe, I am trying it out on RS485. I'm triggering on the rising edge. The RS485 is running at 25Mhz.
Does the eye diagram look good?
Could I double the speed (50MHz) and be ok? (...
- 84.9k
0
votes
0
answers
396
views
noise on RS485 with MAX485 on short line with biases
I am connecting an industrial device (controlled over LAN) with RS485 output signal with Arduino via MAX485 board.
I connect the RO (receive out) pin of the ma485 ...
- 167
0
votes
2
answers
80
views
How VFD affects an isolated IOT system
To avoid noise from the external system I tried to isolate the internal completely. So I added DC-DC isolated converter with signal isolation. I have attached the picture. Still when reading data and ...
2
votes
1
answer
258
views
Relay+SMPS = Noise in RS-485 bus
I designed a board with a microcontroller (Atmega328), 3 relays and a RS485 transceiver. The relays control SMPS LED drivers (Meanwell LPF series). The system consists of 10 boards, each one ...
- 21
1
vote
1
answer
995
views
RS485 Waveform while Receiving Data
I was testing the RS485 Circuit, below is my circuit and I connect J5 to my PC using another RS485 to USB converter. In PC through Modscan software I was monitoring the polling and response, a twisted ...
- 687
0
votes
2
answers
253
views
ROV tether: will DC power supply interfere with the control signal?
I'm designing a tethered underwater drone. I think I will use RS-485 for control.
I can either place batteries in the ROV itself or supply it with electricity via tether. In the latter case, will DC ...
- 121
2
votes
0
answers
1k
views
RS485 ground noise problem
I'm using the USB FTDI dongle to convert USB to RS485, half duplex, 3 wires (A+, B-, GND) with 115200 baud rate.
I'm working with controller of NXP (K64) and I'm experiencing random tx enables on the ...
- 193
1
vote
2
answers
487
views
SN75176B RS-485 Transceiver - Low Level Driver Oscillations
I'm trying to interface an Arduino Mega2560 to a Modbus RTU device using an SN75176B transceiver, on a solderless breadboard at this stage. When I'm driving DE high and writing serial data out of the ...
- 356
2
votes
2
answers
347
views
Wiring 800kHz signal together with RS485 on Cat5
I'm planning to have short (~1m) RS485 runs @<500k baud to transmit some data between PCBs. These PCBs also have a few addressable LEDs (WS2812B) that send data at 800kHz.
Would it be problematic ...
- 7,964
4
votes
3
answers
13k
views
RS485 noise problems: signal ground / common ground / isolation?
I'm experiencing a lot of noise in an RS485 network I've put together using ST485 chips. The cable lengths are very short (<1m total cable length), I'm properly biasing the A and B signals and I've ...
- 343