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Questions tagged [rs232]

RS-232 is the electrical standard used on most serial ports. Note that this standard is a +/- 15 volt system and requires a FDMI converter to make it compatible with TTL logic levels.

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Powering a device from the RS485 lines

I have found multiple RS232 to RS485 converter dongles (from different brands, models, and makes) that do not need external power to operate. Connect the RS232 DB9 on one side, and three wires for the ...
Steven Smethurst's user avatar
1 vote
1 answer
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RS232 Noise problem

I designed an stm32mp1 mpu based pcb. When I connect from the m4 core and send the uart message, everything is as it should be. However, when I start the first stage bootloader from the a7 core, a one-...
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RS232 isolated communication via MAX3250

I have a two diffrent boards. One of the board is send the SoC and other things to Charger Board. While charging progress starts I want to isolate this to device because battery ground is isolated to ...
MSB's user avatar
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Split RS232 RX line on 3 interface

I have a device that sends data (telemetry) over an RS232 serial port. The RX line is not used, this device only sends one string every second. I need to read this data from 3 different devices, each ...
Federico Massimi's user avatar
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Why does RS-232 Communication fail between these 3 ESP32's?

What's the Goal? Trying to get two esp32's to communicate over their UART lines using RS-232. My initial inspiration and idea for the connections was based on https://esp32io.com/tutorials/esp32-rs232 ...
jouell's user avatar
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Proximity sensor (3 Wire NPN or PNP) to RS-232

I do have 2 proximity sensors (level sensors) with 3 wire design. They offer to be PNP or NPN and I need to implement them into an RS-232. They are supplied by 24 VDC. Is there somewhat like a ...
Kinetik1703's user avatar
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1 answer
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Convert RS232 signal to USB

I have an optical amplifier that uses RS232 and I want to convert to USB. I've purchased this chip, also here. There is little documentation on this chip and the supplier hasn't responded to questions....
andrewhunter's user avatar
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What do the different LED lights indicate on a DB-9 tester and what can I infer from them? [closed]

I have a machine with an RS-232 port. When I power ON the machine and connect the DB-9 tester all the machine's troubleshooting guide requires is to check if the RTS light is green. I see there are ...
Sachin 's user avatar
4 votes
4 answers
2k views

Could RS-232 data be carried over a standard 3.5mm audio/aux cable?

I am looking at RS-232 control for various TV displays which use a different type of input connector for RS-232. The combination of RS-232 inputs on different TV displays is the standard 9-pin DB9 ...
James White's user avatar
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1 answer
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Odd behavior using the MAX3323EEPE to translate RS232 output to TTL logic levels

simulate this circuit – Schematic created using CircuitLab I am using the MAX3323EEPE Maxim IC in order to attempt to take RS-232 output from a peripheral and shift it down to TTL logic levels ...
BitBrigade's user avatar
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max3232 disconnection suddenly - problem

Hi I use a Max3232 chip to connect the RS232 between the microcontroller(STM32F103) and an HMI, the problem is that sometimes this connection will be disconnected and no longer work, this may happen ...
Ashkan Khajeh's user avatar
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2 answers
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STM32 UART without HAL library

I am writing register level code for STM32F4 & in my code there is a timer for calculation of the frequency of an input signal. I am trying to implement a UART for sending calculated data to ...
MSB's user avatar
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2 answers
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RS232 and RS485 sharing same wires

I'm planning a serial port that can either work as RS485 (half duplex mode) or as RS232 (configurable by the user). There are several UART to RS232/485 chips around (like LTC2873), where a GPIO ...
Sandro's user avatar
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Can TCC-100/100I Series Industrial RS-232 to RS-422/485 converters with optional 2 kV isolation convert RS485 to RS232? [closed]

I want to convert RS485 to RS232 to connect it to a Moxa Nport 5610 - 16 port RS-232 Ethernet serial device server. Can I use a TCC-100/100I Series Industrial RS-232 to RS-422/485 converter to convert ...
suraj s kumar's user avatar
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Ethernet to UART (or RS232) conversion

For the PCB I'm designing, I need serial communication (1.8V UART, 3.3V UART, 5V UART or RS232, whichever is easiest) from an Ethernet connection (the devices connected to the Ethernet network will ...
Sandro's user avatar
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1 vote
1 answer
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RS232 : dedicated signal ground or common with power ground?

I'm designing the PCB for a robot, where I plan to add some connectors for external RS232 tools (provided by the client). Each connector will provide power (either 24 or 48V, at 5A max) and an RS232 ...
Sandro's user avatar
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1 vote
2 answers
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Is it okay to call a UART “RS-232” if it doesn’t respect voltage levels specified in the RS-232 standard?

I have been using this converter call it converter A to communicate an MCU through its UART pins RX TX. And I wouldn't call this RS232 because RS232 is about physical layer and voltage levels as ...
pnatk's user avatar
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PIC16F UART Receives only the first byte

I'm currently working on a PIC16F18855, I'm trying to set up the communication part. My setup is as follows: A PCB connected to my computer via a TTL232 cable. The PIC16F18855 is clocked at 32Mhz, the ...
Benito's user avatar
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3 answers
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How to prevent power transfer (reverse current) between two DE-9 RS-232 cables? [closed]

we have two USB host devices that communicate with each other and as part of the chain, we are using two Serial to USB cables to connect them, like this: We are not 100% sure as this happened at a ...
policenauts's user avatar
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1 answer
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ESP32-S3: Serial stops working after a random period of time

I am using a ESP32-S3 Dev Kit (Arduino code) connected to a MAX3232 to read data from a solar inverter. I am facing a strange problem as follows: The UART (Serial1, ...
Ziad Akiki's user avatar
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0 answers
48 views

What to look for when selecting a cable for transmitting multiple types of signals in a moving environment

I'm working on a device that involves transmitting data between a microcontroller and an IMU device housed on a different PCB. The two are connected via a cable using a mini DIN connector. I've ...
E.HP.S's user avatar
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1 answer
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MAX3232 ESE+ Not Working but ST3232C and MAX3232 Working on same PCB

I have designed a pcb for Rs232 to TTL, UART converter for using ESP32. I will control an LCD with ESP32. Some IC's (MAX3232 ESE+) heating at the first start. and not working just heating and heating. ...
mehmet's user avatar
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4 votes
2 answers
663 views

When designing a product that uses a DE9 connector, is it normal to just classify it as an RS-232?

Question: When designing a product that uses a DE9 connector, is it normal to just classify it as an RS-232? Background: I am seeing a lot of references to RS-232 while reading engineering documents ...
Samuel Barthelemy's user avatar
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2 answers
203 views

Can I Use RS232 Library For RS422 in PIC Microcontroller?

I have this project where I have to use RS422 and Max485 serial communication. The task is simple: The input from 15 buttons should be send to PC by RS422 using PIC18F4620. I have no experience in ...
Line Follower's user avatar
2 votes
4 answers
778 views

Isolation on RS232 bus

Is there any "simple" way to get (1500V) galvanic isolation on RS232 (just RX and TX)? By isolating, I mean than I have 2 different grounds on each side of the insulation barrier. On side A, ...
Sandro's user avatar
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3 votes
0 answers
403 views

Can RS-232 DB-9-compatible cable be used as a physical medium between two CAN bus DB-9 ports?

Note: I am not talking about connecting an RS-232 device to a CAN bus! I am strictly interested in reusing a RS-232 cable with two DB-9 connectors (one male and one female) to connect two CAN devices, ...
rbaleksandar's user avatar
0 votes
1 answer
112 views

Unable to clear faults on Monoblock via RS232 command: Need help decoding serial messages with Arduino

I recently purchased an XRB160PN192 Monoblock with a known fault of high voltage (HV) for a low price to use in my graduation project. After reading the user manual, I found that the HV error, along ...
Amr Sohil's user avatar
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1 answer
121 views

Modbus ASCII messages delimiter

I need to implement Modbus messages reception over UART. For RTU it's easy because UART on my uC has configurable idle receive line detection. However, for ASCII the task is tricky - the delimiter is ...
asiemasz's user avatar
1 vote
1 answer
275 views

RS232 DCD over Serial-USB Adapter

I've been reading about PPS in linux and GPS synchronization. I stumbled on some sources recommending using a USB GPS, I'm nto quite sure I understand how the interrupt signal is passed through. The ...
Morten Nissov's user avatar
0 votes
1 answer
231 views

Why does the data observed on a UART/RS232 bus look different between a logic analyzer and an STM32 Debugger?

I'm trying to communicate with a BNO055 using an STM32L552ZET6Q microcontroller via UART. The BNO055 is on a separate board, and connected to the STM32 via a 1.5M cable. Additionally, there are ...
E.HP.S's user avatar
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0 votes
1 answer
596 views

Capturing serial output from PuTTY

I have a microcontroller set up to capture serial data via RS-232 so that I can debug directly and view registers, variables, etc. I am using PuTTY through a USB to RS-232 converter to send data to it ...
nobby's user avatar
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1 vote
1 answer
238 views

Convert RS232 signal to I2C/CAN/MAVLink signal

I have an airspeed sensor that outputs a RS232 signal: https://www.aeroprobe.com/micro-air-data-system/. I want to connect this sensor to the Pixhawk in order to use the data for my controller ...
Simon Henn's user avatar
1 vote
1 answer
733 views

How to correctly wire RS 232 when data and power inputs are from different devices?

I'm trying to get nav signals from my flight simulator to my hand held GPS. The GPS (an Aera 796) sits in a cradle with bare wires coming out that would normally be tied into devices and power behind ...
Eric Christoph's user avatar
7 votes
3 answers
2k views

Must RS-232 devices use the same logic level?

I want to interface a microcontroller with the RS-232 COM port of my PC. My PC uses a 75232G IC, which uses +/-12V logic levels as per some multimeter tests. Currently I'm planning to use the ...
StefanoN's user avatar
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2 votes
1 answer
183 views

On a (Windows) PC, can the TxD pin on COM1 be bitbanged? If not, why not?

In this question: Why usb to serial port converter can’t program avr microcontroller? Cornelius claims: "DTR and RTS are the only pins of the serial port that can be bitbanged." But is that ...
AHiismak's user avatar
0 votes
2 answers
890 views

Is it possible to transmit/receive 16 bits in single symbol with the UART?

In the "Universal Serial Bus Class Definitions for Communications Devices" document there is the "Class-Specific Request Codes" table. In this table there is the GET_LINE_CODING ...
Arseniy's user avatar
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0 votes
2 answers
581 views

How do I know if it's RS232 levels or TTL levels

I have a random device: GT MEDIA V8 Finder Pro. I would like to communicate over its console port. Here are some pictures of its mainboard. Here is the area around the console connector: I have no ...
LimetaPeta's user avatar
1 vote
1 answer
68 views

How to develop an ESD circuit protection

I am trying to solve what seems to be a common issue of the MAX232 chip getting burned by electrostatic interference. To solve this issue alternative chips are available on the market such as the ...
floxia's user avatar
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0 votes
3 answers
188 views

Switching RX and TX of RS232 level shifter

I am using a RS232 level shifting board with a raspberry pi. The board is connected to the pi using VCC, ground, RxOut->UART-Rx and TxIn->UART-Tx. I try to avoid buying a null-modem-cable, can I ...
Palm's user avatar
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0 votes
1 answer
114 views

How to switch between multiple signals

I have a board that has a MAX232 and a MAX485. I want to switch between these peripherals' RX/TX signals which connected to Arduino. How would I achieve this? I am definetly not knowledgeable about ...
Orlando Dlugoš Čeh's user avatar
4 votes
4 answers
1k views

Can a PC side software detect that a com-port receive a single stop-bit instead of double stop-bit? [closed]

Let's say we set the com-port settings on the PC side with double stop-bit. And then we set the com-port settings on the device side with single stop-bit. Can we detect stop-bits mismatching with ...
Arseniy's user avatar
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2 votes
2 answers
184 views

MAX3232: change output to be positive only

I have an existing product with a spare RS232 port on the rear panel. This is connected in the standard way to a MAX3232. I would like to use this to connect to another device that is TTL level, so I ...
StephenC's user avatar
-1 votes
3 answers
668 views

Which MAX3232 IC's for simple UART to RS232 converter?

I am trying make a TTL to RS232 converter. I have designed my PCB for 16 pin SMD sop16 and max3232 CSE+. But when I was buying from a store (store link), I saw other types of max3232. I've bought and ...
mehmet's user avatar
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3 votes
1 answer
501 views

RS232 LED matrix programming

I managed to pick up two 16x64 unbranded LED matrix for next to nothing. My son has autism and absolutely loves LED scrolling signs so I thought it would be a nice project to build for him. They have ...
d0little's user avatar
  • 133
5 votes
2 answers
405 views

When the RS232 call is canceled, which pin transmits it to the DTE?

According to my research: When the call to DCE in the RS232 protocol arrives at the ring indicator (9) pin is activated and information is sent to the DTE. Let's say we talked for a while and we had ...
dmrmuhammet's user avatar
3 votes
1 answer
579 views

Force RS-232 DTR active

I have a vending machine that has a RS232 port. I'm trying to get data through another protocol called MDB to get telemetry data, but I really think that it only outputs data through MDB if the RS232 ...
ricreis394's user avatar
1 vote
1 answer
387 views

How does using an RS232 splitter affect the data transfer speed?

I am converting digital data into an analog signal through the RS232 PCIE card I added to my PC. I have a desire to collect data from up 8 different RS232 connections and I am looking into using an ...
PositiveSlope's user avatar
1 vote
2 answers
999 views

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 ...
jlaufer's user avatar
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5 votes
2 answers
1k views

What standard defines the number of stop bits in RS-232?

There is an option in many terminal programs or ICs to set 1 stop-bit, 2 stop-bits or 1.5 stop-bits. Is there any standard that says the RS-232 can have only 1/1.5/2 stop-bits but can't have 0.5 or 3 ...
Arseniy's user avatar
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0 votes
1 answer
230 views

How is the output of this circuit RS232?

I'm trying to design a multi-channel USB-RS232 adaptor (inspired by this) to go into a larger design. After hunting a little, I found this schematic in the datasheet for FTDI's FT4232, which is the ...
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