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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Issue at programming the power supply via RS232 interface

I’m trying to program DC power supply which I recently bought via RS232 interface. When I try to send commands, I always get '0' value as a return no matter which command I sent. I’m hoping someone to ...
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Help with a RS232 (+-12 Volts) to USB converter [closed]

I have a device I want to communicate to with the following signals: This is a programmable power supply, an IPS-405. I have determined from the image above, which is all that is available in the ...
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Relay controller without the relays? [closed]

I need a way to turn off/on about 20 relays or FETs using RS-232 codes. (I do not want to program a generic microcontroller, I want a dedicated device that is designed to do switching only.) I notice ...
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Control a large number of switches with RS232 via discrete logic

I am working on a device that requires controlling a large number of switches by RS-232. The designer wants to use a microcontroller. So in that scenario, a code is sent via RS-232 to the ...
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Doubts about Max232 IC chip

I have a Max 202 Ic and Max 232 Ic I currently want to make a USB to RS232 Serial Db9 converter i have the db9 male port, a max 232 and max 202 , usb female port and bunch of other passive components ....
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Can I connect two microcontrollers via RS232 separated by a distance of 3.5 inches? Both are on two separate PCBs

This design has two PCBs, each with a microcontroller. One can be said to be main and the other is a possible expansion if the user wishes to use it. The microcontrollers will communicate via RS232 (...
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6answers
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Is Ethernet synchronous or asynchronous serial?

I already tried googling but I cannot find an exact answer. Some say it is synchronous, some say asynchronous. For example, see these links: https://www.quora.com/Is-Ethernet-synchronous-or-...
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What was the communication protocol used on board the Apollo moon lander?

It seems that the development of TTL was contemporary ~1961 the maiden moon landing of the Apollo vehicle, while the development of one of the oldest digital signalling standards RS232 using the UART ...
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troubles getting serial port tv to work

i recently posted a question, but didn't had an answer (my fault :) ). my question wasn't straight-forward and clear. so my final goal is to communicate between nodered (raspberry-pi) and my lg tv. I'...
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Why don't LG RS232 commands work when the TV is on (only responds when off)?

I'm writing a new question after stumbling across this question which appeared to have similar symptoms: LG RS232 Commands partially working. As the other question noted, the power on command ...
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Teraterm to show hex data [closed]

I am getting UART data from micro-controller to PC. Micro-controller sends data in hex(eg.0x1B) format which can range from 0x00 to 0xFF. I want teraterm to display the received data in hex format. Is ...
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Running Multiple 12V Sensors to RoboRIO

We run anywhere from 4-10 sensors from Banner Engineering (Photoelectric and RFID). They use 12V power and have a PNP output. Each sensor is 4 wires (12V, GND, NO, NC). Our goal is that we can run the ...
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Connecting RS232 GPS Board to Raspberry Pi

I purchased a NEO-6M GPS board to connect to my Raspberry Pi, and when I bought it I didn't realize that it was meant for RS-232 communication instead of UART TTL (which I believe is what the ...
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32 views

Send Serial data and Ethernet data both over WiFi [closed]

we have to make an upgrade in the system which currently uses serial communication using RS 232 which is wired(obviously). send video data via ethernet. So now we want to add send both the data over ...
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Building a RS232 switch [closed]

I have an RS232 input and 2 audio lines that I want to switch to either computer A or computer B depending on the state of a physical toggle switch. Can anyone point me in the right direction of what ...
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Understanding jtag between microcontroller and devices

I am trying to understand how a micro-controller (in this case a C2000 from TI) communicates with other devices via jtag. The device here is a FT2232 (a jtag to usb converter). According to the figure,...
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How to interface a thermal printer to an Arduino

I've a thermal printer which has TTL, RS232 & a four pin interface. I want to connect it to an Arduino and take printouts with it. It has the following pinouts: RS232 & TTL GND TXD RXD DSR ...
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2answers
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Using USB-RS232 adaptor for USB-TTL connection? [closed]

Seems there are plenty of questions relating going in the opposite direction, but I couldn't find anything that really told me if I could do this.. I have one of these https://uk.rs-online.com/web/p/...
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RS232/TTL converter with Arduino not recognized as serial device

My goal is a very basic one: I want to communicate from my microcontroller to my PC/phone via RS232. I bought a TTL/RS232 converter like this. And since my PC does not have a RS232 port I am using a ...
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MAX233 problem with receiving data

I need to make serial connection between regular PCs and a 3.3v TTL device, I using the Maxim 233 which has internal capacitors. I have the PCs incoming TD connected to R1_IN and RD T1_OUT. The ground ...
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2answers
111 views

Is it possible to carry RS232 signals over a USB cable?

Is it possible to carry RS232 signals (115200 baud rate) over a USB cable? I don't want to use FTDI's RS232-USB converters. I just want to carry TXD, RXD and GND signals over a USB cable. Are my ...
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TTL to 232 with no conversion?

I was reading a blog about someone's application to ingest a TTL signal to a device and got perplexed. The author connects what appears to be a 3.3V TTL signal directly to a RS232 port (and it ...
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Custom ATMEGA2560 with RS-232 Communication Problem

I made a custom PCB using ATMEGA2560 with 2 MAX3223 RS-232 ICs (because they were available to me) but only one Tx channel is working on both ICs and I can't receive anything on any of them. I tried ...
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M-Bus level converter

Hello I am looking for an M-bus level converter. It has to support rs232 for hooking it up to a raspi. I have 5 slaves so 20 unit loads should be sufficient. I am not able to find a suitable product ...
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Opto-isolated RS232 signal capture

I have a problem in which I need to capture (spy on) an RS232 signal through an opto-isolator. This isolator needs to be high speed since the RS232 signal can reach up to 115200 baud. The main problem ...
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1answer
123 views

3.3V TTL to other formats and impedance matching [closed]

I am trying to convert a 3.3V 50 Ohm Impedance TTL Pulse-per-second into other formats (GPIB, USB, RS-232, etc.). I've found some format adapters/convertors like the MAX232, but I am either ...
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3answers
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USB to Serial (RS-232) cable not displaying data on Arduino serial monitor

My previous post (Pictures from the previous post as well) So far all of the answers and comments yielded no solution to my problem. This post offers a different method to communicate serially with ...
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Slow down rs232, 9600 (locked) to 300 for vintage printer

I have an old GE terminal (late 70s) that I'm trying to use and an old serial printer. The RS-232 port is locked at 9600 baud but my TI Silent 700 (late 70s) is 300 baud max. I've tried to Google ...
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4answers
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Cannot communicate with serial device via an Arduino Nano serial communication

I am trying to communicate with an RFID reader via its serial port. The serial port has an RS232 connector on it. I also want to display the RFID tags ID on a 16x2 LCD screen using an Arduino. I, ...
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1answer
170 views

How to debug serial communication with RealTerm?

I am trying to debug an LCD device with an RS232 UART interface. I am using RealTerm on a Windows 10 machine. The UART interface works properly. I have checked the sending device, using an ...
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Detect RS232 lines activity

Trying to work out a simple LED indicator scheme for UART lines(3.3V) and wanted to know if this seemed appropriate. my signals baud rate can be vary from 9600 to 115200. I tried below circuit but not ...
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Bi-Directional RS-232 / RS-485 translator using MAX3162 IC [closed]

I'm trying to communicate with an I2C bus using the Serial Card in my PC (NI PCI485/8). I've created a circuit using the MAX3162 to translate from RS485 to RS232. Then I use the MAX3232 as a level ...
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History question - why are logic levels inverted between TTL and RS232?

I'm just looking for a historical answer as to why TTL and RS232 don't transition logically in the same directions. The signals are the same, but basically level-shifted and inverted. Was there a ...
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1answer
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What kind of serial cable do I need? (TTL vs RS232)

So I have a headless NAS that I'm trying to connect to via a serial console so I can install a different OS. It has a 3.5mm jack on the back I/O labeled COM1. I had ...
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Chip shorting to ground when connecting the grounds

I have a pcb that converts USB to RS232, it is using a CH340G and a MAX2323. The output when not connected works as expected. I try to connect it to a separate device that has its own power supply. ...
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Multidrop bus protocol on the BeagleBone Black PRU

I am truying to implement the MDB protocol on the BeagleBone Black, the problem is : the protocol requires a 9 bit data via UART (9th bit used to differentiate if the sent/received data frame is an ...
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1answer
295 views

Multidrop RS232 - Diode selection and doubts

i'm currently using this reference schematic to wire up 10 RS232 slaves in a "multidrop" configuration (The slaves are some ATMEGA328P with MAX232 Trancievers in order to make a real RS232 ...
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RS232 RFID reader not working

I have purchased an RFID reader that communicates using an RS-232 cable. I have however used an RS-232 to USB adapter to connect it to my laptop. It is an ACM812A RFID reader. When I open the RFID ...
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1answer
287 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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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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1answer
51 views

GSM DCE to TCP - mocking a GSM modem

I'm trying to interface a device (Opentherm thermostat) that actually supports to be controlled through SMS via a serial connection to a GSM modem. I'd like however to control it through TCP rather ...
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Interfacing stm32 with MAX232

I am interfacing MAX232 with STM32F030k6. I have very recently found out that Max3232 would be a better choice, because it works with 3,3 volt. But I am eager to know if UART reciever pin of the ...
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RS232 comm problem

I have two devices (Lambda power supply and custom controller) that communicate via RS232 at 9600 baud using 3 wires. A direct connection does not work properly (PS doesn't respond) but if I connect ...
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Power loss shutdown occurring with Pico UPS

I'm currently suffering from issues where my raspberry pi appears to lose power over time and shut down (I'm using a pico UPS to handle file safe Shutdown). From the symptoms i'm seeing it appears ...
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1answer
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Trying to work out the pinout of an RJ10 (or RJ 11) RS232 port,

New here so please bear with me ;-) I have a salt chlorination system for my pool, which includes a unit that tests the water for Chlorine and PH. It has an 'RS-232' port on it, which is supposed to ...
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1answer
172 views

RS232/CAN switch circuit

I am working on a communication switch that is digitally controlled and I am using four MUX506IPWR from TI to choose the output channel. The switch has on the input a DSUB9 for a CAN channel and a ...
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UART communication with a Thorlabs chip

I am trying to configure a Thorlabs temperature driver (MTD415TE), using a UART-USB connection. For this, I am using a Foca v2.2 with a FT232R USB-UART cable. I am using serial terminals such as ...
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1answer
55 views

Frame Errors (Character Stretching) of CP2102N

When I send a data stream from my PC to a CP2102 USB-to-Serial Bridge, the data coming out of the RS232 side is sometimes corrupted. The receiving micro (an ATmega2560) reports frame errors when this ...
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2answers
102 views

RS232 Communication Voltage Level

I understand that RS232 Communication voltage levels should be between 3 and 25 Volts for positive voltages and the equal negative for negative voltages, but is there a source that can explain the ...
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1answer
136 views

Garbage on RS232 and no the baudrate IS correct

I have a device like this https://www.vaisala.com/sites/default/files/documents/WXT530-Users-Guide-M211840EN.pdf. Some facts: I have an FTDI to USB board from Sparkfun which is tested to work with ...

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