Programming :: Serial Port Communication Program Always Lose One Byte Data: 0x00?

Dec 13, 2009

I wrote a serial port communication program to access a equipment.

int main(void)
int fd = 0;
int nread = 0,i = 0,nwrite = 0, tmpread = 0, m = 0, n = 0 ;


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Programming :: Serial Port Program Not Outputting The Right Data?

Apr 11, 2009

I have connected a device to my linux system with a serial cable (rs232). The settings are: port /dev/ttyS0, baud rate=38400, data bits=8, stop bits=1, no parity, no hardware or software handshaking. I wrote a linux program that sends 1 byte to the device, but the device doesn't receive it. I know the serial ports are working because when I use the CuteCOM application to send data, the device DOES receive it, so obviously it is a problem with my code..


#include <stdio.h>
#include <stdlib.h>
#include <math.h>


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Programming :: Get Data From Serial Port Function Read() Blocks When Data Not Available?

Jun 11, 2009

I am using read() in c++ to get data from a serial port. However, if no data is available on the serial port the function blocks until dta arrives.Example code:

char m_readBuffer[255] = {0};
char* p_curChar = m_readBuffer;


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Programming :: Memcpy Fails To Copy Data / But Byte By Byte Assignment Work

Jul 6, 2011

I got across a peculiar problem with memcpy.History:writing a code which do flash/Read functionality for SPI Parts.

1.memory map the Flash chip registers to userspace. - fine
2.Issue block read command
3.Just print the data I got, using the memory mapped address - fine I got the correct data.
4.Copy the data to a local buffer from memory mapped address using memcpy - FAIL

on SUSE 11.3 -32 bit the above code worked perfectly, but on SUSE 11.4 - 64bit , Ubantu, Fedora it failed.
I am using gcc compiler obviously. I am using i386/x86_64 OS. Processor: Intel core 2 duo, SNB after step 4 , when I dump the data from local buffer every thing is FF.But step 4, if i implement byte by byte copy using assignment operator, it there any known bug with memcpy? am I missing anything?

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Programming :: Intercept Data On Serial Port?

Dec 21, 2010

I dont know if this is the right forum, But I try to find a solution, I want to intercept data from/to serial port without disrupting the software that manages the serial port, (I would like to save the data to a file or sent into a socket) I searched somes modules and programs (linspy, ttysniff, interceptty, maxty ...), A bit complicated (There are some diff. between kernel 2.4 and 2.6), So I'd like to change the serial port driver to intercept the "read" and "write " and do what I want with the data, I'd like to know what do you think about

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Programming :: Send Data Through Serial Port Using C?

Oct 20, 2009

I am not a profession programmer. I have to write a C code which send some command to attach display using C program. Can any one please help me in this regard.

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General :: Establish Serial Port Communication Through USB In System?

Jun 30, 2011

I am new to Ubuntu and I need to establish a serial port communication between my PC and microcontroller MSP430G2452.

On connection the USB available with the Launchpad and using lsusb.

It identifies the port as:

Bus 005 Device 003: ID 0451:f432 Texas Instruments, Inc. eZ430 Development Tool

After establishing such a connection what I need to do? My aim is to send a byte of information in Linux.

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Ubuntu :: Open The COM1 Port To Do Serial Communication Via PHP?

Mar 15, 2010

Not really sure where to post this, so here goes... I installed apache2, php and MySQL via LAMP and everything seems to work fine but when I try to open the COM1 port to do serial communication via PHP, I get a permission denied error.

'mode com1: BAUD=9600 PARITY=N data=8 stop=1 xon=off';

I've also tried using /dev/ttyS0 instead of COM1: but no luck. Anyone out there know what I'm doing wrong? I don't know if I need to set something up in apache2 or php or if the code is just wrong. I'm on an Acer Aspire One with Ubuntu's LNR 9.10.

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Programming :: Displaying I/O Possible When Reading Data From The Serial Port?

Aug 31, 2009

I have got a problem while reading from the serial port. I'm working on iMX-31 board and Eclipse IDE. Whenever I'm trying to read any data through the serial port, it's displaying I/O Possible and the application is being terminated. After reading I'm trying to write this data on a file. Here are the excerpts from the code:

# int main()
if (openport()<0)


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Programming :: Read Some Data From Controller Using Serial Port?

Aug 25, 2010

i want to try with a small application in linu in that i want to read some data from controller using serial port and i wanna transfor that data to another meachin in the network for this i want serial port interfacing programming as well as socket programming.

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Networking :: Setting Up Serial Communication From Desktop Through USB Port In Terminal?

Jan 15, 2010

I am new to linux terminal programming and all but i want to set up a simple serial communication from my desktop through USB port. The actual idea to to write some data in the terminal and build a terminal program that sends the data to the usb port with a fixed baud rate. are there ready made terminal programs available for this simple communication?or atleast any Graphical tools which could help me build and design such a terminal in ubuntu 9.04?

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General :: Serial And Parallel Data Communication On Fedora 13

Apr 22, 2010

I have been trying out serial and parallel data communication on Fedora 13 Beta. I can easily see the list of serial ports through:

setserial -g /dev/ttyS[0-3]
And can also write some data through:
ll > /dev/ttyS0
But I am unable to see parallel ports
I can see something like:
But when I try out:
ll > /dev/parport0
It throws error.

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Programming :: Send /receive Data Through Serial Port In Fedora?

Dec 27, 2010

I am doing work on serial port. I want to send/receive data to/from Microcontrolar through serial port. But I don't know how to initialize, receive and send data to Serial port. i am new in fedora so i hav'nt any deep concept of fedora.can anyone send me C code , which communicate through serial port in fedora (or atleast help me). I am using Fedora 11.

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Programming :: Serial Port Data Read Time Interval?

Oct 30, 2010

I am writing a C program which reads data over serial port. While reading data, if I send my data(which is a 13 byte structure) periodic with a period of 1 second for 10 times I read it without problem and I read the data 10 times as I sent and as I expectBut if I send data continuousuly(without any time interval between each sending) 10 times I can only read 1 of them(I can only read it once).

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Programming :: Porting Serial Port Program From Windows?

Jan 8, 2009

I bought a set of 3 laser sensors and it came with a software and its C++ source code for windows to receive the lasers info through the serial port. Since the entire project is running on Linux, I need to port the windows code to Linux. At the present moment, I already can receive the data from each of the 3 sensors, but the info is coming concatenated! Tracking down the original windows code, I found that it is probably happening cause I didn't ported these lines to my Linux version:


CommTimeouts.ReadIntervalTimeout = 2;


I've searched already about how to specify the serial port timeouts on Linux, but didn't find a solution. how to port these lines to Linux or maybe where to find more info about how to set serial port timeouts on Linux?

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Programming :: Debian Serial Port Read() Return Wrong Data?

Jul 6, 2010

I am implementing a simple serial protocol where my ARM9 board, running Linux is communicating to a slave peripheral board. The Master sends a 12 byte data stream and the peripheral board returns status in a 23 byte response. The serial port is opened in raw mode. It works perfectly on 44 reads; however, on the 45 read the data returned from the read() is incorrect. I've framed what's being sent on an oscope and it is correct.The coincidence is that 23 x 44 = 1012. It's as though the receive buffer is 1K and when I go past the boundary I get bad data. The read following the bad one is good again.I've tried flushing the buffer before reading but get the same result.Here's the port initialization code:

int initport(int fd)


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Programming :: Write Data To Text File Which Is Coming On Serial Port Infintely?

Aug 5, 2010

trying read serial COM port and want to write that received data to file, now its writing only one sentence, but i want to write full file which coming on serial port, as i'm sending file from hyper terminal and reading on linux pc, If i put while loop its not writing anything,without while loop its writing only one line and if send big file then application terminates and then writes to file.But i need do write any size which coming on serial port.Finally i want write full file which is coming on hyper terminal, after writing the file it has wait for next data. This is my code,

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


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Networking :: Serial Port : Read Data, Not Reading Complete Data?

Mar 5, 2010

I have an application where I am sending data via serial port from PC1 (Java App) and reading that data in PC2 (C++ App). The problem that I am facing is that my PC2 (C++ App) is not able to read complete data sent by PC1 i.e. from my PC1 I am sending 190 bytes but PC2 is able to read close to 140 bytes though I am trying to read in a loop.Below is code snippet of my C++ AppOpen the connection to serial port

serialfd = open( serialPortName.c_str(), O_RDWR | O_NOCTTY | O_NDELAY);
if (serialfd == -1)


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Programming :: Communication Data Between Different Process

Nov 22, 2010

I would like to send struct data from process A to process B but I dont known what is the best way. I have read about IPC, but there are a lot of ways to do it.

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Programming :: Find Where Error - After "strcat", Data All Become 0x00

Oct 18, 2010

I create a http client to send data to server. The code :

int main(int argc, char *argv[])
int sockfd;
char buffer[1024];
struct sockaddr_in server_addr;
//struct hostent *host;
int portnumber,nbytes;


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Programming :: Appropriate Interprocess Communication With Data Preservation?

May 29, 2011

I am searching for an interprocess communication that is platform and language independent and is two way communication among different processes and the most important thing is the ipc should have the ability to store data until the receiver receives it.

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Networking :: Serial Port : Not Able To Write Big Chunk Of Data?

Mar 10, 2010

I am trying to send text data from one PC to other using Serial cable. One of the PC is running linux and I am sending data from it using write(2) system call. The log size is approx 65K bytes but the write(2) system call returns some 4K bytes (i.e. this much amount of data is getting transferred). I tried breaking the data in chunks of 4K but write(2) returns -1.My question is that "Is there any buffer limit for writing data on serial port? or can I send data of any size?. Also do I need to continously read data from other PC as I write 4K chunk of data"Do I need to do any special configuration in termios structure for sending (huge) data?

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Software :: Identify The Status Of Serial Port ("Port Already Opened") From A C Program?

Feb 5, 2010

I am writing some application in C, which will access a serial port device (RS232). My application is working good. But if any other application is already opened the port, I couldn't able to identify that. In windows VB program, while accessing comport through mscomm control, i am receiving an error as "Port Already Opened". But in Linux environment, through C program how can i get that? I am accessing comport 1 as follows

fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_SYNC);

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General :: Serial Port Programming Help

Apr 15, 2010

can we use inb() and outb() functions for serial port programming ??

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Programming :: C - Serial Port Won't Open?

Sep 1, 2010

I'm using C serial in a program to open and use a serial port but the port won't open for one reason or another. The program successfully runs on a different computer and when using RealTerm: Serial Capture Program, I can connect through the serial port with the same settings as I'm attempting through my c code. Anyone have any idea why it might be failing? I know this is still pretty vague, so let me know if there's other things I can tell you that might help to finding a solution

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General :: Serial Communication In Between VM And ESX?

Apr 28, 2010

I am in verse to understand the serial communication between guest and host.I have just added a serial port through VI Client selecting "Use serial port on host"(host being ESX host).If I am on VM and run :

ll > /dev/ttyS0

I understand that it should get displayed through ESX Host. So On ESX Host, I typed:

cat /dev/ttyS0

But nothing worked !

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Programming :: Read X Bytes From Serial Port?

May 5, 2010

I am trying to write some code that interfaces with an AVR over a serial port. Basically I send a command then read the output which is 6 bytes. I need to receive all 6 bytes before the program continues. Is there a way to do this? If I use read() it returns -1 unless I add a delay before reading the port. Is there a way to get it to read the 6 bytes as soon as they arrive?In python you simply say how many bytes you want and the max time you are willing to wait which seems a whole lot easier than read

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Programming :: Serial Port Communications - CPU Bandwidth

Sep 15, 2010

I have an application written in C (by somebody else) monitoring a device connected to a serial port. I'm using an old laptop w. tinycore linux for an os. The app works well enough, and the communication speed is relatively slow, 9600bps, unidirectional, comes in packets of 18 bytes. The app is just picking apart the packets and displaying the contents on a formatted screen (ncurses), updating about once every 1/2 second. The trouble is, the app is polling the serial port and using *all* of the cpu bandwidth. The cpu fan runs full bore all the time.

Other activities are sluggish when the monitoring program is running. I'd like to modify the app to be a little more intelligent, use a receive buffer and interrupts to trigger processing each packet and, most importantly, not poll in a tight loop waiting for data. I'm not sure where to start, but I'm convinced this isn't that complicated of a change. Is there a good resource that would explain the basics of reading data from serial port software buffers, triggering on interrupts and suspending or sleeping when no interrupt is pending?

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Programming :: Multiple Protocols On Serial Port

Mar 24, 2011

I'm attempting to write an application that needs to read and reply to messages that will appear via 3 different methods:

1) Standard serial communications
2) TCPIP over serial via PPP
3) TCPIP over Ethernet

The problem is that I'd like for the application to be able to receive packets from any and all of the three interfaces simultaneously. I shouldnt have much trouble with performing #1 and #3 at the same time, as I think I can just get a file descriptor from termios and another for a socket and then use select to wait for data. But #2 is problematic.

First I dont know how to set up a socket that uses PPP as the data link layer. And secondly, (here's the big one) this PPP data is coming over the same port that the serial data is. There's no chance for data collision, and I am guaranteed not to receive another packet until I respond to the last one (in the same protocol at that) but incoming packets may or may not be PPP/TCP/IP framed.

My app will act like the PPP client, so I was just thinking "somehow" that I could run a standard termios application on the serial port which would begin to interpret the packet. If its PPP framed then it would have to get passed to a PPP client, which would be listening to my application rather than a physical port. And I have no idea how to do that. Is there an API available that will help me with the PPP packets?

How hard would it be to write a device driver that simulates a serial port. The device can listen on a real serial port, interpret its contents to an extent, and then distribute the incoming data to multiple "virtual" serial ports, which the main application can then listen to for incoming traffic.

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Programming :: Opening A Serial Port From Interrupt?

Aug 17, 2010

I'm trying to open ttySx from an interrupt.the kernel crashes. is it possible to open/write to serial port from interrupts ? I think it crushes because when I try to open the device there is a mutex lock which cause the kernel to crash , am I right

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