RS-232 is the electrical standard used on most serial ports.

learn more… | top users | synonyms

0
votes
1answer
29 views

Protecting GND from RS-232 voltages

I have a project that uses this two wire RS-232 trick: http://circuitcellar.com/cc-blog/one-wire-rs-232-half-duplex-ee-tip-135/ It combines RX/TX into one wire while the other is ground. However, ...
0
votes
0answers
52 views

rs232 verilog & c++

I am now working on a project using fpga rs232. I want to send the data from the computer via c++ writefile. When the computer sent the data to fpga it will show the result on the led. My problem is ...
0
votes
2answers
80 views

Using UART's TX & RX for Separate Functinality

I am using PIC18F4520. The project requirement is to interface GSM module with uC as well as receive commands from PC via serial port. to achieve this I have connected Microcontroller- TX to GSM ...
3
votes
1answer
328 views

RS-232 for approx 1600ft

I am using a cable of approx 1600ft to enable communication between two computers using RS-232(pins 2,3 and 5). On checking the transmitted signal on the oscilloscope, i get the output as below (hex ...
0
votes
1answer
42 views

High 4bit crash in atmega128 serial communication

I am trying to communication between atmega128 and serialCom(PC), but I get a pretty strange bug. When I send data 0 to 255 (char) from atmega128 to serialCom(PC) ,after sending 0x08, the high bit ...
0
votes
0answers
33 views

RS232 Termination Resistor for MAX202IPW Application

Should I terminate the Rx and Tx lines for RS232 Transmiter MAX202IPW or there is already a built-in termination? What termination resistor should I pick, and how it should be connected. In the ...
4
votes
2answers
542 views

UART synchronization [duplicate]

I am trying to understand UART synchronization. In a UART, the default state is high, and it starts the reception process when it receives a start bit (high-to-low transition) In some scenarios any ...
0
votes
1answer
58 views

xmega serial communication using MAX3232

Hi I am trying to talk to send a character to the PC using the xmega128a1 and the MAX3232 USART to Serial converter chip. Here is my setup and "send char" function below: ...
1
vote
1answer
81 views

What kind of RS232 protocol uses just pin 2 and 4 on a DB-9 connector. This is what is sent from a Tenma model 72-6870 Digital Multimeter.

I have several Tenma model 72-6870 DMMs in our physics lab that use a 2 wire data transfer set up. Does anyone have any information that could leed me to understanding this type of data protocol? ...
0
votes
2answers
66 views

Connect several RS-232 ports into one

I will have several devices with atmel microcontrollers which I'm going to connect to PC using RS-232. Is there any way to connect several devices into one RS-232 port? (Let's assume RS-232 can handle ...
0
votes
1answer
70 views

RS232, RS422 Splitter— EDIT fot JTAG [closed]

Is it good to use one UART interface on MCU, RX_UART for receiving data from RS422 receiver and TX_UART for transmitting the same data to the RS232 and RS422 transmitter? I am trying to use UART as ...
2
votes
2answers
168 views

PICDEM board and Linux connection through serial

TL;DR: I can open screen or putty session in terminal to the /dev/ttyUSB0, but characters ...
0
votes
1answer
205 views

How can I send keyboard input to USB port or Serial Port?

Now, I am using Windows 8 and have made Arduino buttons to operate as an keyboard's 4 arrow keys(up,down, right and left). From this moment, I am going to send this keyboard input event out to the USB ...
0
votes
2answers
101 views

Microcontroller Interface with Modbus Serial [closed]

I'm a beginner and I'm trying to acquire data from a microcontroller with Modbus serial protocol in order to create an interface with LabVIEW. I'm using a Prolific Technology USB-RS232 converter and ...
0
votes
1answer
62 views

Can i directly connect a gsm shield to a computer without using arduino?

Ok, i've bought a gsm900 in alexan, and what i bought was a gsm shield thinking that it is really just the same only that shield can be placed directly in an arduino. The problem is that, im trying to ...
1
vote
2answers
129 views

Send analog audio through the rs232 port of a data transmitter

I would like to convert an analog audio signal into an rs232 datafeed to send it through a data transmitter and receive it at the other end. I already have the data transmitter and receiver. Thanks ...
0
votes
2answers
109 views

Convert usb scale output to serial

I would like to convert the usb output of a scale to a serial format so I can read it through a com port. I saw this tutorial from adafruit Adafruit serial scale but that scale is not available ...
0
votes
1answer
83 views

Modbus raw data COM capture file example?

I'm attempting to use a RS232 tap to sniff a serial connection between two devices that are communicating using Modbus RTU. I'm looking for any capture files taken from sniffing a COM connection or ...
1
vote
1answer
49 views

Question about FTDI USB-to-Serial Evaluation board [closed]

The evaluation board I am talking about the FTDI EVAL232R evaluation board which can be found at the bottom of this page. It employs a FT232RL IC. What I want to do I would like to connect a USB ...
0
votes
1answer
108 views

RS232/RS485 Converter Circuit Receiving Problem

I'm trying to make an RS232/RS485 converter circuit. I used a circuit from http://airborn.com.au/layout/232cnv/232to485.html site and i changed some components on that circuit. Then I established my ...
-4
votes
2answers
52 views

Conversion of RS232 to USB [closed]

Can anybody explain how FT232R or CP2102 or some Serial to USB converter and it magically appears as COM port on PC? I would appreciate a detailed explanation on how the conversion happens. Some ...
1
vote
2answers
98 views

Control door with RS232 or Ethernet relay

Our company use a fail safe electric bolt with a remote control for the entry door. It closes when the power is ON and vice versa. It does work normally but I want to make a hot button for the ...
0
votes
2answers
46 views

Need to get sensor data from a Arduino Pro Mini to a Arduino Mega that is about 150 feet away from each other

So like the subject line states... Need to get sensor data from an Arduino Pro Mini to a Arduino Mega that is about 150 feet away from each other (maybe slightly less) both operating at 5VDC. Do I ...
0
votes
1answer
155 views

UART - getting gibberish data from MAX232 with PIC16F877A mcu

I have created a serial communication between my laptop and 16F877A mcu. I have used MAX232EPE IC as level converter also. According to my code If I send a character to the MCU, MCU will return a ...
1
vote
1answer
53 views

Grounding of a PCB that communicates with a PC via USB or RS232

I have a PCB with an atmega8, communicating with a PC. The signal from TX and RX pins is level-shifted through a MAX232 to standard serial port level, then converted via serial-to-USB commercial ...
2
votes
1answer
91 views

How can I troubleshoot stuck/flipped bits in a serial connection?

I'm working on reverse engineering some scrap vaccuum fluorescent displays from Noritake that lived their previous lives inside a payphone. No datasheet exists for it since it's a custom part; ...
0
votes
1answer
71 views

Is it possible to use Microcontroller I/O ports as UART ports

I am using NXP P89LPC954 Microcontroller in my design.It has two UART ports. As it is known that UART are point to point connections between two devices. Hence i can only use two devices to connect to ...
0
votes
2answers
143 views

USB-232 converters - rts/cts latency problem

I am integrating the USB controller FT230X into a new product. It interfaces directly with the 32 bit Cortex M4 MCU, the STM32F303x The receive buffer on the STM32 is only 2 bytes deep, which I ...
12
votes
5answers
5k views

Max Serial Cable Length?

What is the maximum length of serial cable I can use, to connection work properly? Is length of serial cable in connection with baud rate? I am using about 5 meter cable at speed 38400 bauds and RS232 ...
0
votes
2answers
193 views

Has anyone built an rs232 to usb converter?

I want to implement serial communication into one of my projects, but I'm hesitant to use a serial cable due them them being exceedingly hard to find nowadays. I found an old converter and took it ...
0
votes
1answer
533 views

STM32 RS485 connection

I want to interface stm32f0 with rs422 (half duplex and full duplex). What I'm not getting how to connect RE and DE signals to rs 232. From UART I'll be having RX, TX, VCC and GND pins which i need to ...
2
votes
0answers
104 views

RS232 to TTL converter problem

I have a RS232 to TTL Converter which has 4 pins Vcc, Tx, Rx, GND . I am trying to make a serial communication with my PC. I have a AVR development board and I have tested my program by connecting ...
0
votes
3answers
604 views

Serial, RS232, Modbus, UART and TCP

I want clearly know this, Serial is protocol right? Then what is the Modbus? Is it under serial. And what are RS232 and RS485? What is UART and serial and UART same? What about TCP? TCP and serial ...
0
votes
1answer
58 views

RS232-TX voltage translator

Would like your help to clear my doubt and confusion for this circuit http://nil.rpc1.org/wordpress/?p=31. I don't get a sense that how possible the RS232-pin3 TX signal is converted and transmitted ...
0
votes
1answer
180 views

How to transmit data from an analog multiplexer to an RS232 COM port on a PC

I am having trouble understanding how to design a circuit that will transmit multiple analog data signals to a computer through one RS232 COM port. The analog data is a simple voltage reading from ...
2
votes
1answer
2k views

Max232 giving incorrect values at pins

Background: I'm trying to connect a Compact Logix PLC -> MAX232CPE Maxium chip -> arduino. Currently my PLC does communicate modbus RS232 with a request for data from the arduino. I can see this by ...
0
votes
3answers
166 views

PIC MCU to PC Serial Communication Problem

I was just trying to send continuous stream of letter 'G' from my PIC MCU (PIC18F452) to my laptop. Here is my assembly code that i am using : ...
0
votes
4answers
330 views

What is a 3 wire type cross linked serial cable?

I'm trying to use a controller which uses Serial communication with the PC. The documentation says I need to get a 3 wire type cross link serial cable. Is this a null modem cable? The following ...
0
votes
1answer
118 views

How to transfer data between RS-422 and RS-485 ports? [closed]

I'm relatively new to behaviors of serial ports such as RS-232, RS-422, and RS-485. I'm wondering how do you initiate data transmission between a system and a device connected to each other thru one ...
0
votes
2answers
241 views

“Unable to open parallel port I/O driver” when trying to connect “RS232 to USB” cable on Linux

I have a JDM programmer for pic micro-controllers, but it came with RS232 port. I have bought a "RS232 to USB" cable with its driver for Windows only and I use Xubuntu 14.04 LTS. I have tried ...
0
votes
4answers
403 views

Why use MAX232 when using USB-to-Serial cable

I was wondering the need to use MAX232 type ICs when using a USB to RS232 converters. A prolific based converter gives the following output, when transmitting 'a' It seems to me that a simple NOT ...
1
vote
1answer
113 views

Questions about an atmega32 serial-bus to RS232 with converter and different logic levels

I have an atmega32 and a FUM DCF-U atomic clock (signal receiver and decoder) of HKW-elektronik. The µ-controller works with 5V and the module on 3.3V. I have to build a converter, because the ...
-1
votes
1answer
132 views

RS232 ISP programming

I have a saleae digital analyzer and i am using it to listen to on a ISP programmer. (not to steal someone's code, but to build my own programmer). It only has two wires (GND & SDA) The data just ...
0
votes
3answers
255 views

How to program an ATMega328 using a Serial Port without using programmers such as USBasp

I am currently learning electronics. I recently bought an ATMega328 and an USBasp programmer to begin my learning. But I couldn't use the USBasp to program my chip. So I researched on other ways to ...
0
votes
1answer
100 views

Simple Interrupt Handling program?

I'm new to Embedded programming and I'm trying to understand how Interrupt handlers work in different contexts/scenarios. I just want to know how a interrupt handler would work in the following ...
0
votes
1answer
765 views

Serial Communication with rs232/485 and rj45

I am working a project where I want to connect and control, using Labview, TDK-Lambda Power Supply Process Vacuum Controller Ion Gauge (MODBUS interface) They both have rs232/rs485 capabilities, ...
6
votes
5answers
4k views

Why is USB cable maximum length is shorter than in RS232?

Why do we need to buffer USB signal if the cable is longer than 5m? Is that because a signal voltage drop? Is that because it drives currents?
0
votes
2answers
156 views

Generate TTL-level reset pulse from RS-232 level signal

(My knowledge of analog circuit design is severely limited). I am trying to generate a reset pulse for an AVR microcontroller. The reset is active LOW, and the maximum threshold voltage is 0.9V, with ...
1
vote
2answers
209 views

Is some protection necessary for a RS232 link between PIC-MAX232-Computer?

I have a circuit with a dsPIC which communicates to a computer using a MAX232 (there ain't any optical isolation). The circuit ground is not bounded to the earth. But the equipment case is earthed. ...
2
votes
2answers
412 views

How to protect a MAX232 from PIC programming high voltages?

This question is derived from this Board review thread, I thought it would be preferable to make it a standalone question. I want to be able to reset a PIC remotely using the only communication port ...