StatusFlags reading fail from Serial Port.

Hi,
I got this error when running SimpleRead for trying to open a VCP(Virtual Com Port - usbserial ) on Knoppix with netbeans JDK1.4 and CommApi 3.0.
java.io.IOException: Erro getting StatusFlags in call to ioctl(TIOCMGET)
at com.sun.comm.LinuxSerial.nativeGetStatusFlags(Native Method)
at com.sun.comm.LinuxSerial.isCD(LinuxSerial.Java:203)
at com.sun.comm.LinuxSerial$SSCheckStatusThread.run(LinuxSerial.java:598)
Does anyone know what the cause?? Please help....
FYI, Simplewrite works as successfully open and send a string to the port.

a quick search on ora_ffi in this forum offered the following thread Access Serial/ COM Port through Forms 10g
hope this helps.

Similar Messages

Problem while reading data from Serial Port

Hi All,
I am facing some problem while reading data from Serial Port.
As per the requirement I am writing the data on Serial Port and waiting for response of that data.
Notification for data availabilty is checked with method public void serialEvent(SerialPortEvent event) of javax.comm.SerialPortEventListener.
When we are writing data on the port one thread i.e. "main" thread is generated and when data availability event occures another thread "Win32SerialPort Notification thread" is generated. This creates problem for me as we can't control thread processing.
So can anybody pls explain me how to overcome this problem?
Regards,
Neha

My Problem is:-
I am simoultaneouly wrting data on port & reading data from port.
First I write data on port using outputStream.write() method. Now when target side sends me response back for the request on serial port DATA_AVAILABLE of SerialPortEventListner event occured,we are reading data from serial port.Now till the time we didn't get the response from target next command can't be written on the serial port. When we are writing data on port main thread is executed.Now my problem starts when DATA_AVAILABLE event occured.At this point another thread is created.Due to this my program writes data of next command without reading response of previous command.To solve this prob. I have used wait() & notify() methods as follows.But again due to this my pc hangs after execution of 2 commands. (PC hang in while loop in a code provided below.)
From SOPs I could figure it out that after 2 commands we are not able to write data on serial port so DATA_AVAILABLE event doesn't occure n pro. goes in wait state.
Can anybody help me to solve this issue.
Neha.
Code:
public void serialEvent(SerialPortEvent event)
          switch (event.getEventType())
               case SerialPortEvent.BI:
               case SerialPortEvent.OE:
               case SerialPortEvent.FE:
               case SerialPortEvent.PE:
               case SerialPortEvent.CD:
               case SerialPortEvent.CTS:
               case SerialPortEvent.DSR:
               case SerialPortEvent.RI:
               case SerialPortEvent.OUTPUT_BUFFER_EMPTY:
                             break;
               case SerialPortEvent.DATA_AVAILABLE:
                    try
                         dataThread = Thread.currentThread();
                         dataThread.setPriority(10);
                         dataAvailable = true;
                                                                                byte[] tempArray=new byte[availableBytes];
                                    inputStream.read(tempArray);
                                                                   catch (IOException io)
                         SOP(io, "Error in serialEvent callback call for event DATA_AVAILABLE");
public void writetoPort(byte[] data) throws IOException
                         outputStream.write(data);
                          while(finalTimeOut >= actualTime)
                        if( ! dataAvailable)
                                actualTime = System.currentTimeMillis();
                       else
          synchronized (mainThread)
               mainThread = Thread.currentThread();
               mainThread.wait();
public void sendDatatoUser(byte[] b) throws Exception, HWCCSystemFailure
          obj.returnData(b);
          synchronized(mainThread)
               mainThread.notify();

Problem in reading data from serial port continuously- application hangs after sometimes

I need to read data from two COM port and order of data appearance from COM port is not fixed.
I have used small timeout and reading data in while loop continously . If my application is steady for sometime it gets hangs and afterwards it doesnt receive any data again.
Then I need to restart my application again to make it work.
I am attaching VI. Let me know any issue.
Kudos are always welcome if you got solution to some extent.
I need my difficulties because they are necessary to enjoy my success.
--Ranjeet
Attachments:
Scanning.vi ‏39 KB

billko wrote:
Ranjeet_Singh wrote:
I need to read data from two COM port and order of data appearance from COM port is not fixed.
I have used small timeout and reading data in while loop continously . If my application is steady for sometime it gets hangs and afterwards it doesnt receive any data again.
Then I need to restart my application again to make it work.
I am attaching VI. Let me know any issue.
What do you mean, "not fixed?" If there is no termination character, no start/stop character(s) or even a consistent data length, then how can you really be sure when the data starts and stops?
I probably misunderstood you though. Assuming the last case is not ture - there is a certain length to the data - then you should use the bytes at port, like in the otherwise disastrous serial port read example. In this case, it's NOT disastrous. You have to make sure that you read all the data that came through. Right now you have no idea how much data you just read. Also, if this is streaming data, you might want to break it out into a producer/consumer design pattern.
Not fixed means order is not fixed, data from any com port can come anytime. lenght is fixed, one com port have 14 byte and other 8 byte fixed..
Reading data is not an issue for me as it works nice but I have a query that why my application hangs after sometime and stops reading data from COM PORT.
Kudos are always welcome if you got solution to some extent.
I need my difficulties because they are necessary to enjoy my success.
--Ranjeet

Read data from serial port or TCP port of frontend PC

Hello Friends,
I have requirement to read data from device connected to frontend PC which will provide meter reading data.
Vendor has given me two option.
1. Device can be connected to seiral port and data transfer will be done through MODBUS RTU protocol.In that case data need to capture from serial port.
2. Device can be connected to TCP port and Socket program can be provided for data transfer. In that case SAP will act as client and communicate with TCP port.
There will be multiple workstation with individual meters connected to them.
I am aware of text file interfacing through front end tools using custom code using VB,JAVA or others.
Is there any solution availble to achieve above things using ABAP other than text file , like direct communication?
I am using ECC 6.0.

Hello,
Socket programming in not available on ABAP, but you may use RFC for the same.
Use the below links for more details
[Link 1|http://help.sap.com/printdocu/core/print46c/en/data/pdf/BCFESDE2/BCFESDE2.pdf]
[Link 2|http://forums.sdn.sap.com/thread.jspa?threadID=1820233]
Regards,
Abhishek

Reading data from serial port needs optimisation

Hi,
We have got a class which reads input from some hardware connected to the serial port.
The data coming from the device can cross over 1mb at a time.
We would like to optimize the speed of the program such that no data is lost during the readings.
Hence, we would like to store the entire reading into memory such that it can be stored into a file or database once the readings have been completed.
The serialport class returns a byte[] of the current data in the buffer. There could be over 8000 such readings.
Would it be better to convert the byte[] into a char[] and append into a StringBuffer
or append the byte[] as is into an ArrayList and perform the conversions and operations on it later?
Reg,
Chetan

The ArrayList will not only be much faster but it will preserve the original data. Unless the incoming data really is a String there is no point in converting it.

Reading datas from serial port (palm)

Hi,
Because read methods (DataInputStream, stream on palm serial port) are blocking, how do I know if there is at least one available byte that can be read ?
Thanks

Hi,
I thought the method available() resolve the problem but this method gives the number of byte available without blocking.
I use :
public DataInputStream dis = null;
public int readDataBuf(byte[] buf) {
int status = -1;
try {
if (dis.read(buf, 0, 1) > 0) {
status = (buf[0] & 0xFF);
catch(IOException e) {
System.out.println(e.toString());
return status;
but with the read method if there is not byte the program stop wainting a byte.
Thanks

Reading a char array from Serial port

Need help!
Hi, I've got the following problem - I wanna read a input stream from serial port and I use at the moment the following method (reading bytewise):
public String receiveText (){
      byte ch;
      fStrBuf.delete(0,fStrBuf.length()); //clearing the buffer
try{
          do {
          ch = (byte) fPortInStream.read();
          fStrBuf.append( (char) ch);
        while ( (byte) ch != 0x03); //The end of frame byte
         }catch(IOException ioe) {};
      return fStrBuf.toString();It works pretty well, but disadvantage is that it's too slow to use it in the thread (at least I think so)
How can I change it to read all available data from the port (or simply faste). I don't need event listeners, because it's a request-responde communication.
I tried smth. like this
byte[] readBuffer = new byte[20];
            try {
                while (fPortInStream.available() > 0) {
                    int numBytes = inputStream.read(readBuffer);
                    fStrBuf.append(readBuffer);
            } catch (IOException e) {}
      return fStrBuf.toString();But it doesn't seem to work :-(

May I suggest that you use StringBuilder rather than StringBuffer. It has less overhead because it is not threadsafe. I do synchronous serial port stuff with Opto 22, and i have no listeners enabled.
Appending to the String(Builder/Buffer) directly from the byte buffer mangles it. So I use a string (ugh). With the Opto22 brain boards, i am looking for a carriage return as a term char. It either finds it or times out.
This is the best i have come up with so far:
StringBuilder response = new StringBuilder();
String data = new String();
long msTimeOut = 2000;
public void getResponse () throws IOException {
        byte[] readBuff = {0};
        int charAvail;
        response.delete(0,response.length());
        long ts = Calendar.getInstance().getTimeInMillis();
        try {
            while ( readBuff[readBuff.length-1] != '\r' ) {
                charAvail = inputStream.available();
                if ( charAvail > 0 ) {
                    readBuff = new byte[charAvail];
                    inputStream.read(readBuff);
                    response.append(new String(readBuff));
                if ( Calendar.getInstance().getTimeInMillis() > (ts + msTimeOut) ) {
                    response.delete(0,response.length());
                    response.append("TIMEOUT");
                    break;
        } catch (IOException e) { e.printStackTrace(); throw e; }
        data = response.substring(0);
    } I just starting writing Java about 4 days ago, so caveat emptor.

How to get data from serial port to GUI textArea

From Serial Port.....
Messages from base (always 5 bytes):
0xAA, 0, 0, 0, 0xBB - IDLE Mode
0xAA, 0, 0x80, 0x80, 0xBB - Question Mode
messages from terminal (always 6 bytes):
0xAA, a, b, c, chksum, 0xBB
where chksum = a+b+c;
a = address (0-250)
the 2 MSB's of b represenet the answer:
0 0 - A
0 1 - B
1 0 - C
1 1 - D
the 6LSB's of b and 8bits of c is the time for answer, in milliseconds.
(0-16384 milliseconds)
I have VB Code for that but I want the same thing in Java ...
Can any one help me?
Here's VB Code..
VERSION 5.00
Object = "{648A5603-2C6E-101B-82B6-000000000014}#1.1#0"; "MSCOMM32.OCX"
Begin VB.Form Form1
   BorderStyle     =   1 'Fixed Single
   Caption         =   "Aakar GUI"
   ClientHeight    =   4665
   ClientLeft      =   60
   ClientTop       =   375
   ClientWidth     =   6105
   LinkTopic       =   "Form1"
   MaxButton       =   0   'False
   MinButton       =   0   'False
   ScaleHeight     =   311
   ScaleMode       =   3 'Pixel
   ScaleWidth      =   407
   StartUpPosition =   3 'Windows Default
   Begin VB.CommandButton cmdPort
      Caption         =   "Open Port"
      Height          =   375
      Left            =   120
      TabIndex        =   4
      Top             =   600
      Width           =   1455
   End
   Begin VB.ComboBox cmbPort
      Height          =   315
      ItemData        =   "Form1.frx":0000
      Left            =   120
      List            =   "Form1.frx":0016
      Style           =   2 'Dropdown List
      TabIndex        =   3
      Top             =   120
      Width           =   2895
   End
   Begin VB.CommandButton cmdEnd
      Caption         =   "End"
      Height          =   495
      Left            =   1560
      TabIndex        =   2
      Top             =   1320
      Width           =   1215
   End
   Begin VB.CommandButton cmdStart
      Caption         =   "Start"
      Height          =   495
      Left            =   120
      TabIndex        =   1
      Top             =   1320
      Width           =   1215
   End
   Begin VB.TextBox txtMessage
      Height          =   2040
      Left            =   119
      MultiLine       =   -1 'True
      ScrollBars      =   3 'Both
      TabIndex        =   0
      Top             =   2475
      Width           =   5848
   End
   Begin VB.Timer tmrRead
      Enabled         =   0   'False
      Interval        =   1
      Left            =   2040
      Top             =   600
   End
   Begin MSCommLib.MSComm MSComm1
      Left            =   3120
      Top             =   360
      _ExtentX        =   1164
      _ExtentY        =   1164
      _Version        =   393216
      DTREnable       =   0   'False
      ParityReplace   =   45
      SThreshold      =   1
   End
   Begin VB.Label Label5
      Caption         =   "Result Data:"
      Height          =   375
      Left            =   120
      TabIndex        =   5
      Top             =   2115
      Width           =   1320
   End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
Dim PortIsOpen As Boolean
Dim Answers(4) As String
Dim RejectKeystroke As Boolean
Private Sub cmbPort_Change()
Debug.Print cmbPort.ListIndex
End Sub
Private Sub cmbPort_Validate(Cancel As Boolean)
'Cancel = True
End Sub
Private Sub cmdEnd_Click()
MSComm1.Output = "e"
txtMessage.Text = ""
End Sub
Private Sub cmdPort_Click()
On Error GoTo ErrorHandler
If cmbPort.ListIndex < 0 Then Exit Sub
If PortIsOpen Then
    cmbPort.Enabled = True
    MSComm1.PortOpen = False
    PortIsOpen = False
    cmdPort.Caption = "Open Port"
    cmdStart.Enabled = False
    cmdEnd.Enabled = False
Else
    MSComm1.CommPort = cmbPort.ListIndex + 1
    cmbPort.Enabled = False
    MSComm1.PortOpen = True
    PortIsOpen = True
    cmdPort.Caption = "Close Port"
    cmdStart.Enabled = True
    cmdEnd.Enabled = True
End If
Exit Sub
ErrorHandler:
Debug.Print Err.Number
Debug.Print Err.Description
MsgBox Err.Description, vbExclamation Or vbOKOnly, "Error opening port"
cmbPort.Enabled = True
PortIsOpen = False
cmdPort.Caption = "Open Port"
cmdStart.Enabled = False
cmdEnd.Enabled = False
End Sub
Private Sub cmdStart_Click()
MSComm1.Output = "s"
txtMessage.Text = ""
End Sub
Private Sub Form_Initialize()
Dim tmp As Variant
tmp = InitCommonControls
End Sub
Private Sub Form_Load()
Answers(0) = "A"
Answers(1) = "B"
Answers(2) = "C"
Answers(3) = "D"
'MSComm1.Settings = "9600,n,8,1"
''MSComm1.Settings = "115200,n,8,1"
'MSComm1.PortOpen = True
On Error GoTo ErrorHandler1
MSComm1.CommPort = 1                    ' comm port 1
MSComm1.RThreshold = 1                  ' use 'on comm' event processing
MSComm1.Settings = "9600,n,8,1"         ' baud, parity, data bits, stop bits
MSComm1.SThreshold = 1                  ' allows us to track Tx LED
MSComm1.InputMode = comInputModeText    'comInputModeBinary ' binary mode, you can also use
                                        ' comInputModeText for text only use
PortIsOpen = False
cmbPort.ListIndex = 0
' open the port
MSComm1.PortOpen = True
cmbPort.Enabled = False
PortIsOpen = True
cmdPort.Caption = "Close Port"
cmdStart.Enabled = True
cmdEnd.Enabled = True
Exit Sub
ErrorHandler1:
Debug.Print Err.Description
PortIsOpen = False
cmbPort.Enabled = True
cmdPort.Caption = "Open Port"
cmdStart.Enabled = False
cmdEnd.Enabled = False
End Sub
Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
If MSComm1.PortOpen Then MSComm1.PortOpen = False
End Sub
Private Sub lblOption_Click()
End Sub
Private Sub MSComm1_OnComm()
' Synopsis:     Handle incoming characters, 'On Comm' Event
' Description: By setting MSComm1.RThreshold = 1, this event will fire for
'               each character that arrives in the comm controls input buffer.
'               Set MSComm1.RThreshold = 0 if you want to poll the control
'               yourself, either via a TImer or within program execution loop.
'               In most cases, OnComm Event processing shown here is the prefered
'               method of processing incoming characters.
    Dim i As Long
    Dim sBuff    As String           ' buffer for holding incoming characters
    Const MTC       As String = vbCrLf ' message terminator characters (ususally vbCrLf)
    Const LenMTC    As Long = 2         ' number of terminator characters, must match MTC
    Dim iPtr        As Long             ' pointer to terminatior character
    ' OnComm fires for multiple Events
    ' so get the Event ID & process
    Select Case MSComm1.CommEvent
        ' Received RThreshold # of chars, in our case 1.
        Case comEvReceive
            ' read all of the characters from the input buffer
            ' StrConv() is required when using MSComm in binary mode,
            ' if you set MSComm1.InputMode = comInputModeText, it's not required
            'sBuff = sBuff & StrConv(MSComm1.Input, vbUnicode)
            'If Len(txtMessage.Text) > 4096 Then txtMessage.Text = ""
            sBuff = MSComm1.Input
            Dim ch As String
            Dim PacketStart As Boolean
            Dim PacketLength As Integer
            Dim Packet() As String
            PacketStart = False
            PacketLength = 0
            While (Len(sBuff) > 0)
                ch = Left(sBuff, 1)
                If (ch = Chr(&HAA)) Then PacketStart = True
                If (ch = Chr(&HBB)) Then PacketStart = False
                If (ch <> Chr(&HAA) And ch <> Chr(&HBB)) Then
                    PacketLength = PacketLength + 1
                    ReDim Preserve Packet(PacketLength)
                    Packet(PacketLength) = ch
                End If
                'txtMessage.Text = txtMessage.Text + Format(Hex(Asc(ch)), " @@")
                sBuff = Right(sBuff, Len(sBuff) - 1)
            Wend
            If (PacketLength = 3) Then
                Debug.Print "Command packet recieved"
                'txtMessage.Text = txtMessage.Text + vbCrLf + "Address =" + Str(Asc(Packet(1)))
                'txtMessage.Text = txtMessage.Text + vbCrLf + "Address =" + Str(Asc(Packet(2)))
            End If
            If (PacketLength = 4) Then
                Debug.Print "Response packet recieved"
                txtMessage.Text = txtMessage.Text + "Address =" + Str(Asc(Packet(1))) + _
                    " Answer = " + Answers((Asc(Packet(2)) And &HC0) / 64) + _
                    " Time =" + Str((Asc(Packet(2)) And &H3F) * 256 + (Asc(Packet(3)))) + "mS" + vbCrLf
                'txtMessage.Text = txtMessage.Text + vbCrLf + "Address =" + Str(Asc(Packet(1)))
                'txtMessage.Text = txtMessage.Text + vbCrLf + "Option =" + Str((Asc(Packet(2)) And &HC0) / 64)
                'txtMessage.Text = txtMessage.Text + vbCrLf + "Time =" + Str((Asc(Packet(2)) And &H3F) * 256 + (Asc(Packet(3))))
            End If
            If (PacketLength <> 4 And PacketLength <> 3) Then Debug.Print "Unknown packet of length" + Str(PacketLength) + " recieved"
            txtMessage.Text = txtMessage.Text + vbCrLf
        ' An EOF charater was found in the input stream
        Case comEvEOF
            DoEvents
        ' There are SThreshold number of characters in the transmit buffer.
        Case comEvSend
            DoEvents
        ' A Break was received.
        Case comEventBreak
            DoEvents
        ' Framing Error
        Case comEventFrame
            DoEvents
        ' Data Lost.
        Case comEventOverrun
            DoEvents
        ' Receive buffer overflow.
        Case comEventRxOver
            DoEvents
        ' Parity Error.
        Case comEventRxParity
            DoEvents
        ' Transmit buffer full.
        Case comEventTxFull
        ' Unexpected error retrieving DCB]
        Case comEventDCB
            DoEvents
    End Select
End Sub
Private Sub tmrRead_Timer()
'MSComm1.Output = vbCrLf + vbCrLf
'MSComm1.Output = Chr(128)
End Sub
Private Sub txtMessage_KeyDown(KeyCode As Integer, Shift As Integer)
If Shift = 2 Or Shift = 4 Then RejectKeystroke = False Else RejectKeystroke = True
End Sub
Private Sub txtMessage_KeyPress(KeyAscii As Integer)
If RejectKeystroke Then
    KeyAscii = 0
End If
End SubThanks in advance..

I want to replicate the entire VB program as Java Program.
This has to be included in my project which i am doing in java.

How to save a datas from serial port?

How to save a datas from serial port?

Hi
I need some help about rs-232 communication. I want to make a vi witch can do this things:
-read a txt file (to simulate a serial port like when the datas are coming)
i will get 3 different data in serial port (like this: 121 213 135)
i want to save in a txt file what datas get my vi
so
-write in a txt file or draw in a diagram (or both)
so my problem is: read in serial port and save in a file and draw a diagram.
if anybody can help pls HELP ME because im a beginner in this problem.
I already do something but Im not sure that good.
Thx for all.

Count time between 2 readings from serial port... help!.

Hi guys,
I am using my application to get the readings sent by microcontroller from serial port. It works perfectly. But i have the problem, the pic uses 16bits counter, and sometimes i measure frequency lower than 15hz (65535-->16bits). Thats why I thought to measure the time between each pulse that it recieved in serial port. So i could multiply the reading about the time which spend in arrive to serial port. I know if any pulse spend more than 15hz, i should add 65535 to this reading.
Then, the idea is count the time spent between each reading in serial port. SInce pics count and later send each turn.
I dont know if it is possible, and exist any easy way.. Can ayone help me?.
I would like to see any example of it, always it is possible.
Regards, Fonsi.
Attachments:
capture.GIF ‏19 KB

You're not going to be able to get even close to 1 usec resolution using the built-in time functions though I don't see any of those in your attachment. The windows clock is simply not that accurate. If you need to precisely time your serial reads you might want to look at using the timed loop. You can set the period of that to 1 msec.

Unable to capture data from Serial port using LVRT2010 in single core pentium 4 machine

I am using application written in Labview using windows Labview
Runtime environment 2010. Application creates a tunnel to intercept data from
Serial port.
My problem is, Currently, I am using single core Pentium
processor. When I am trying to intercept the data between COM1 and COM7 (COM 7
is a virtual port) it is not able to capture data.
When I am running Labview RT environment using dual core
processor machine it is running normally. I wonder whether it could be the compatibility issues with
single core Pentium processor.

Hi Magnetica
Are both of the machines running the same runtime engine,
drivers ect?
Have you had RT applications running on this
machine before?
Is the development computer a 64bit machine?
The processor is a supported model (See link below).
http://zone.ni.com/devzone/cda/tut/p/id/8239
Regards
Robert
National Instruments UK & Ireland

Reading Data from serial (Comm) Port in developer200 forms 6i

Dears,
I have developed an application using Dev2k forms 6i.
I need to read data from a device (weigh bridge) that is attached to PC on comm port.
scenario: when a vehicle comes on the Weigh bridge it calculates its weight and send it to the PC on serial port.
on when-button-pressed event I want to get data into a text field on form.
If any one has developed such form please help me.
Thanks and regards

you can:
create java class -> wrap plsql -> invoke plsql-code from button trigger
googling java class instead of creating =)

Efficient optimized way to read from serial port and GPS data display using map

Hi,
I have a custom h/w which reads the data from GPS Rx and after parsing send it to PC over RS232.
Each second it sends 201 bytes to PC. I have developed a VI to read the GPS data and display it. Project file is attached.
Fulctionality of different loops are as following:
1. LOOP 1: 1.1 Reads the serial data from com port.
               1.2 Synclonize the frame using start bytes "a" and "z".
               1.3 Reads next 4 bytes containg receiving error information.
               1.4 Reads next 195 bytes. in which initial 80 byes are GPS data. rest are others.
2. LOOP 2: 2.1 Extarcts the GPS information and put them in an array.
                  2.2 Extarcts the receive error infor and counts the total error by incrimenting the variable using shift reg.
3. LOOP 3:3: 3.1 Displays the GPS data in chart and log the data in a file.
4. FLOW : Uses the GMAP .NET based API to creat a MAP and display.
Problem statement:
1. Functionality acheived.
2. However in between data set is being missed by the programm.
Quesitions:
1. Is the developed VI is efficient in terms of using queue loacl variables etc.
2. What are the improvments I can do to solve the problem.
Any other suggestions|
Thank you
jayant
jayant
Attachments:
Telemetry_Receiver_v2.zip ‏3075 KB

One of the most common problems in serial communication is the need for an adequate timing: how much time is expected your device to spend before answering? Have you put and adequate pause in your code before reading from the serial port?
Hope this helps
Roberto
Proud to use LW/CVI from 3.1 on.
My contributions to the Developer Zone Community
If I have helped you, why not giving me a kudos?

Reading ascii codes from serial port and plotting them

Hello
I am trying to build a VI that reads data (ascii values) from the serial port.
I am trying to build a wireless phonocardiogram. I have a microphone that acquires heart sounds. these signals are amplified and sent to a A/D converter to digitize them. the digital signal are sent to a base unit. The digitals signals received at the base unit have to be sent to a computer (over a serial port to view them).
I would like build a VI to plot ascii data received over the serial port.
I would like to plot those values so that the plot just looks like a analog signal (the one I had before A/D conversion).
Can anyone provide me some help?
Thanks in advance.....
Solved!
Go to Solution.

Hi chaitu209
What is your transmission speed, samplerate, and bandwidth needed in your project? The bandwidth of the serial port is somewhat limited. Let me give you an example
Say you are using 115200 Kbit per second as transmission speed, one start bit/stop bit and parity bit, and 8 bit data. This will give you 115200/11 bytes pr second as the maximum theoretical transfer rate/sample rate. But if you are using up to 16 bit AD your maximum samplerate will be 115200/(2x11). So my advise to you is to use a binary transfer protocol not ASCII based protocol. This is not a problem in Labview with serial transmission.
Besides which, my opinion is that Express VIs Carthage must be destroyed deleted
(Sorry no Labview "brag list" so far)

Plot more than one analog value to a waveform chart by reading from Serial Port

I have 4 LDRs and I want to plot their values to a waveform chart by reading them from the serial port. I have looked around and found an example of a VI plotting one value to a waveform chart (attached below) but I am unsure about how to expand this for 4 different waveforms, mostly because I don't particularly understand the way is being read currently. If someone could either point me in the way of a relevant example or explain/show me a solution, or explain howthe current VI I have works, that would be greatly appreciated.
Attachments:
LDRread.vi ‏20 KB

Since I assume each LDR (whatever that is) has its own serial connection, you will need to read from 4 different serial ports. From there, just form an array of all the data and write to the chart.
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StatusFlags reading fail from Serial Port.

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