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)
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Attachments:
Telemetry_Receiver_v2.zip 3075 KBOne 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
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Proud to use LW/CVI from 3.1 on.
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I already stablish communication with my serial port using VISA, selecting COM1 as the resoure name.
After that, I tried to read the data from the port (as we know the data was in string format )but I need to convert the data to numeric value to hadle it (no arrays).
Another main thing is that I'm develoing a new based Embedded design and tthe info that will trhow out from the device to the PC is binary.
How can I solved the problem, and if I want to make bidirectional communication with my system how can I do it? The VISA intructions as *IDN? and so forthetc can be recognize by the external system if the COM1 port is recognized by NI Max as ADSRL1::I
NSTR1?Hello,
For an example of bidirectional serial communication in LabVIEW, please see the shipping example LabVIEW <-> Serial.vi. This can be found from LabVIEW by going to Help >> Find Examples. From the example finder, select Hardware Input and Output >> Serial >> LabVIEW <-> Serial.vi.
Once you are able to read the string data in, you can use the VIs in the String/Number Conversion palette to convert the data to numeric format. To access these, right-click on the block diagram >> All Functions >> String >> String/Number Conversion.
Let me know if this does not help.
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To read & save data from serial port (write to .csv file), and plot data as waveform
Hi,
I've been stuck with this problem for weeks and really need some help. I've been searching a lot but I can't find a proper solution.
I am trying to use Labview to plot and display some parameters of a data acquisition system for a project.
The data acquisition system is connected to a computer via serial connection through COM 1 port.
The data acquisition system sends a serial stream of data (ASCII string with baud rate 19200), as shown below (from HyperTerminal),
01:00:26,933.24,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
01:00:27,931.54,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
The serial data stream consists of a time stamp (as 1st data), followed by 16 individual channel data, separated by comma "," and each stream ending in return "\n". Each value of the data ranges from 1 to 6 digits (value of -5000 to 15000).
I have no problem reading this values correctly using HyperTerminal, but I have problem to plot and display individual parameters of this serial string in Labview. I want to save the entire data in a “.csv” file corresponding to all the 16 channels with time stamp and plot each individual channel parameter in a graph with time on X-axis.
I am relatively new to Labview hope I can learn a lot from your help.
Thank youThank you Dennis.........
Now I had modified the program incorporating1D array for gauge display.....but currently I have a new problem. The program is running updating the file, waveform graph and Gauge very slowly. Approximately once in every 15 seconds 16 data streams are getting updated in a bunch with gauge sticking to the last value rather than indicating real time value.
eg.
12:33:41,-3728.78,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:42,-3730.47,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:43,-3729.81,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:44,-3733.80,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:45,-3733.57,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:46,-3729.27,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:47,-3725.97,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:48,-3730.14,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:49,-3733.20,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:50,-3733.60,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:51,-3732.24,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:52,-3734.51,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:53,-3728.07,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:54,-3732.54,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:55,-3732.24,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
12:33:56,-3731.58,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,
gets updated in a bunch after 15 seconds, rather than in every second. I thought the problem is with while loop but, i realised there is no delay associated with it..... Can u kindly help me in modifing the program so as it can update the waveform, file data and gauge in real time? (I have attached the modified VI file "suitcase new.vi" and the data gathered after executing the same as in "Trail.txt".)
Thank You,
Rahul
Attachments:
trail.txt 85 KB
suitcase new.vi 44 KB -
I am working on a wireless vital sign monitor. I have 3 signals; heart rate and temperature. I filter and amplify the signals before converting them into digital form. I then pass them via MAX232 before passing them to RS232 serial cable.
I am therefore working on a program to receive the combined signal and separate them.
I have come across serial read and write examples on ni.com but am looking for one where I can actually separate combined signals and display them separately.Reading the serial port will give you a string. How you divide the channels depends on how the data was formatted before it was sent over the serial channel.
If you are designing the instrument, as it seems from your query, then you can set up any form you wish. If your data is always floating point numeric, you could use space or tab characters to separate data words. You could use and XML format. If the instrument is provided by a vendor, contact them for the protocol.
If tabs are used between words and returns between sets of readings, the resutlant string can be interpretted by the Spreadsheet String to Array function in LV.
Things to avoid are characters often used by serial communications systems as control characters. Carraige returns are
often used as command terminators by serial protocols, but may also be used by the port.
Lynn -
How to display raw, not ascii, bytes from serial port?
Hello, I have an instrument that outputs raw data, not ascii, bytes to a serial port. How do you display raw data, not ascii, bytes from a serial port? Since raw data bytes are not displayable, there is got to be something in labview to interpret/display the received bytes the way it is as data in HEX or Binary. The STRING-TO-HEX and STRING-TO-BINARY functions are not applicable in this case because the bytes were not string type in the first place. For example, if the receive byte is 0x4D, I need to display 4D in HEX or 77 in Decimal and not the ascii character "M" corresponding to 0x4D ascii code. I am using a VISA-RD function currently to receive the data from a COM port. VISA-RD outputs string type. Thank for any feedback or suggestion in advance.
BC@Baxter wrote:
...The STRING-TO-HEX and STRING-TO-BINARY functions are not applicable in this case because the bytes were not string type in the first place...
Of course they are string type, just not formatted in a human readable form. So, YES, these functions are not appropriate.
BC@Baxter wrote:
For example, if the receive byte is 0x4D, I need to display 4D in HEX or 77 in Decimal and not the ascii character "M" corresponding to 0x4D ascii code.
Dennis is right, but there is no "decimal" display for strings, so the second requirement needs a tiny little bit more code.
If you have a single byte string, you can typecast it into a U8 number and set the display format as decimal, hex, octal, or binary as desired. In decimal, it would display the number 77. Since it is now a numeric, you can even do math with it.
In general, the string has multiple bytes, and you would typecast it into an array of U8 numbers (Since this is an often used function, there is also a "string to byte array" which does the same thing).
Typecasting is the secret. You can e.g. easily typecast 2 bytes into a U16, 4 bytes into a I32, 8 bytes into a DBL, etc. For more detailed requirements, there is also the "unflatten from string". Check the online help for details. Good luck!
LabVIEW Champion . Do more with less code and in less time . -
Reading Ascii charactors from Parallel port???
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[email protected]
to modify thier software to a
Parallel port. so that i could capture.
I have a third party group that is running a process sending and receiving
data
> thru a USB port for control of a frequency test. They are keeping track of
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>
> What I want to do is to send the cycle counts ( which could be up to
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that
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>
> I need ( since RS232 ports are sort of going away on new computer system
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either
> RS232 or USB into Labview 7.1.1 .
>
> I noticed you had drives on your web site with VB and Labview.
>
> Could you guys give me some suggestions if possible.
> Thanks
>
>Hi Forrest,
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Attachments:
Decode and display image.zip 212 KBWell, things are getting a bit clearer now.
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Need help!
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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();
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Can I use LabVIEW to load data directly into system memory from a VI? The serial card I'm using isn't supported by NI nor does VISA recognize it. I'm using a Call Library function to read the data from the card and now I want it to go directly to system memory.
The data is being received at 1Mbps.
ThanksTwo questions:
One, if it's a serial card, then presumably it gives you more serial ports, like COM3, COM4, etc. If so, VISA would see the COM ports, and not the card directly. The drivers for the card should make it so that you see the extra serial ports from the OS. If you don't see the extra COM ports from VISA, then it sounds like the drivers for the card are not installed properly. Do the extra COM ports show up in Device Manager?
Two, you said that you're using a Call Library function to get the data and you want to put it into system memory. Errr.... you just read the data and you have it in memory by definition. Are you saying you need a way to parse the data so it shows up on a graph or something? -
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.
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