DOCUMENT:Q158008 24-JUL-2001 [vbwin] TITLE :HOWTO: Use MSCOMM32.OCX to Transfer Data on DBCS Windows PRODUCT :Microsoft Visual Basic for Windows PROD/VER::4.0,5.0 OPER/SYS: KEYWORDS:kbCtrl kbVBp kbVBp500 kbVBp600 kbGrpDSVB kbDSupport KBSIMCH kbIntlDev ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Visual Basic Control Creation Edition for Windows, version 5.0 - Microsoft Visual Basic Learning Edition for Windows, version 5.0 - Microsoft Visual Basic Professional Edition for Windows, version 5.0 - Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 - Microsoft Visual Basic Professional Edition, 16-bit, for Windows, version 4.0 - Microsoft Visual Basic Professional Edition, 32-bit, for Windows, version 4.0 - Microsoft Visual Basic Enterprise Edition, 16-bit, for Windows, version 4.0 - Microsoft Visual Basic Enterprise Edition, 32-bit, for Windows, version 4.0 ------------------------------------------------------------------------------- SUMMARY ======= This article illustrates some techniques using the MSComm32.OCX control for receiving and transmitting binary data on double-byte character set (DBCS) Windows. MORE INFORMATION ================ The Communications control, MSCOMM32.OCX, provides serial communications for your application by allowing the transmission and reception of data through a serial port where only a string of characters to the transmit buffer is permitted. This feature limits you to transmitting only text- based files. The binary data must be converted one byte at a time to a character and then transmitted. When received, the data must be converted from a character back into binary data one byte at a time. See the REFERENCES section below for more information. On double-byte character set Windows, such as Korean, Japanese, and Chinese Windows, binary data will be corrupted if one of the binary values matches a DBCS lead character. The MSComm control will interpret this byte and the following byte as one double-byte character and return only one byte for the equivalent ASCII character. To resolve this problem, which is specific to DBCS Windows, you can implement certain encoding algorithms that can convert binary data into text data and vice versa. This article demonstrates how to convert one byte binary data into ASCII size of three characters to preserve the lead character. On the receiving end, these three ASCII characters are converted back into one-byte binary data. For example: ASC('a') = 97 ' 97 would be transmitted as three characters: '0''9''7' NOTE: The sample code is reading the input file as binary. It is not necessary to convert each character to ASCII value. If you use a modem instead of RS-232 cable, you need to add some codes to establish the modem connection. For example: - MSComm1.Output = 'ATDT 999-9999' for Transmitter and - - MSComm1.Output = 'AT' for Receiver Once the connection is established, everything should work the same way. WARNING: USE OF THE SAMPLE CODE PROVIDED IN THIS ARTICLE IS AT YOUR OWN RISK. Microsoft provides this sample code "as is" without warranty of any kind, either express or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose. Sample Code - Transmitter ------------------------- 1. Start Visual Basic. If Visual Basic is already running, from the File menu, choose New Project. Form1 will be created by default. 2. Place Microsoft Comm Control on Form1. If Microsoft Comm Control cannot be found in the control bar, go to Tools menu, choose Custom Controls, and then check the Microsoft Comm Control on the List Box. 3. Add the following code to the General Declarations section of Form1: ' General Declaration section Dim Offset As Long Dim FileData As Byte Dim FileName As String 4. Add the following code to the Load event of Form1: ' Load event of Form ' 28800 baud, no parity, 8 data, and 1 stop bit. ' In RS-232, maximum speed of 28800 baud can be used Private Sub Form_Load() MSComm1.Settings = "28800,N,8,1" MSComm1.InputLen = 1 MSComm1.CommPort = 2 MSComm1.PortOpen = True ' Change the file path to point to the file you want to transfer FileName = "d:\sample.hlp" Offset = 1 Open FileName For Binary Access Read As #1 End Sub 5. Add the following code to the OnComm event of MSComm1: ' ONCOMM event of Comm OLE Control ' The following code is needed to make sure that next set of ' characters can be transmitted (CommEvent = 2 is triggered from the ' receiver side) Private Sub MSComm1_OnComm() If MSComm1.CommEvent = 2 Then temp = MSComm1.Input If Offset <= FileLen(FileName) Then Get #1, Offset, FileData q = FileData MSComm1.Output = Format(q, "000") Offset = Offset + 1 End If End If End Sub 6. Add the following code to the UnLoad event of Form1: ' UnLoad event of Form Private Sub Form_Unload(Cancel As Integer) Close #1 End Sub 7. Make sure that the Properties of MSComm1 are changed as follows: RThreshold = 1 ' triggers when at least one char is on the buffer SThreshold = 3 Sample Code - Receiver ---------------------- 1. Start Visual Basic. If Visual Basic is already running, from the File menu, choose New Project. Form1 will be created by default. 2. Place Microsoft Comm Control on Form1. If Microsoft Comm Control cannot be found in the control bar, go to Tools menu, choose Custom Controls, and then check the Microsoft Comm Control on the List Box. 3. Add a CommandButton to Form1. Command1 is created by default. 4. Add the following code to the General Declarations section of Form1: ' General Declaration section Dim ByteCount As Long Dim FileData As Byte 5. Add the following code to the Load event of Form1: ' Load event of Form ' 28800 baud, no parity, 8 data, and 1 stop bit. Private Sub Form_Load() MSComm1.Settings = "28800,N,8,1" MSComm1.InputLen = 3 MSComm1.CommPort = 1 MSComm1.PortOpen = True ' Change the file path to point to the file you want to store Open "c:\sample.txt" For Binary Access Write As #1 End Sub 6. Add the following code to the OnComm event of MSComm1: ' OnComm event Private Sub MSComm1_OnComm() If MSComm1.CommEvent = 2 And MSComm1.InBufferCount > 0 Then FileData = CInt(MSComm1.Input) ByteCount = ByteCount + 1 Put #1, ByteCount, FileData MSComm1.Output = Chr$(26) End If End Sub 7. Add the following code to the Click event of Command1: ' CLICK event of button Private Sub Command1_Click() MSComm1.Output = Chr$(26) End Sub 8. Add the following code to the UnLoad event of Form1: ' UnLoad even of Form Private Sub Form_Unload(Cancel As Integer) Close #1 End Sub 9. Make sure that the Properties of MSComm1 are changed as follows: RThreshold = 3 The Transmitter and Receiver codes should be compiled separately and placed on two separate machines where one machine is the designated transmitter and the other one is the receiver. The event-driven technique generates an OnComm event when there are characters waiting in the input buffer. Also, the CommEvent property will contain a numeric 2. For the OnComm event to be triggered, you must set the Rthreshold property to a value other than its default of zero. The most common setting for the RThreshold property is 1, meaning that the OnComm event is triggered if a minimum of one character is waiting in the input buffer. In this article, the numeric 3 is being used as a value of RThreshold property because 3 characters at a time are being sent. REFERENCES ========== For additional information, please see the following article in the Microsoft Knowledge Base: Q194923 HOWTO: Trap Control Characters Using the MSComm Control Additional query words: Comm KBTRADCH KBSIMCH KBKOREA KBJAPAN kbVBp500 kbVBp600 kbVBp kbdsd kbDSupport kbCtrl ====================================================================== Keywords : kbCtrl kbVBp kbVBp500 kbVBp600 kbGrpDSVB kbDSupport KBSIMCH kbIntlDev Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500Search kbVB500 kbVB400Search kbVB400 kbZNotKeyword3 kbVB16bitSearch Version : :4.0,5.0 Issue type : kbhowto ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.