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Program to read Data From Comm Port

Posted on 2003-12-04
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Last Modified: 2010-05-01
Hello ,
         I am trying to receive data from serial port
( RS232) COMM2 .Give me some ideas to program to get data and to display them.

Thankyou
Karthick
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Question by:karthick2083
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8 Comments
 
LVL 11

Expert Comment

by:bingie
ID: 9877200
For a full code tutorial on reading to and sending from the com port:

   http://www.freevbcode.com/ShowCode.Asp?ID=2236

A good tutorial on the MScomm control:

   http://www.yes-tele.com/mscomm.html

******************************************************************************
You have to make certain that both terminals are configured for the same Baud Rate, Number Of Stop Bits, Number Of Data Bits and Parity Bits. With this not set right, Baud rate mismatch, data mismatch or parity error can occur. This is done with the VB code.

When using the MScomm control, you need to set the properties:

Private Sub Form_Load()
    MSComm1.CommPort = 1                  'CommPort to use
    MSComm1.Settings = "9600,N,8,1"     'Setting BaudRate, Parity (Yes, No, Even), Number of Data Bit, Number of Stop Bits
    MSComm1.InputLen = 0                
    MSComm1.PortOpen = True               'Open the port
End Sub

Private Sub Form_Unload(Cancel As Integer)
    MSComm1.PortOpen = False               'Close the port on form Unload
End Sub

To read from the port:

Private Sub MSComm1_OnComm()
 Dim buffer As Variant
 Select Case MSComm1.CommEvent
  Case comEvReceive
  buffer = MSComm1.Input
  Text1.Text = Text1.Text & buffer
 End Select
End Sub

To send from the port:

Private Sub cmdSend_Click()
 MSComm1.Output = "000000001" + chr$(13) 'chr$(13) is used as a carrige return not necessary somtimes
End Sub

You might also need a null modem cable to simulate the handshaking signals, for proper communication. The null modem is connected to facilitate the connection of 2 "DTE" or 2 "DCE". The cable wiring is important, here is some info on that:

http://www.loop-back.com/null-mod.html
http://www.nullmodem.com/NullModem.htm

Diagrams:

http://www.beckwithelectric.com/relays/m3420/commapp/images/ca_fig05.gif
http://goforit.unk.edu/datacomm/images/dc_00oe.gif
http://www.qsl.net/wb3afl/graphics/nullmdm.gif

To ensure it's done correctly, you can buy pre-made null modem cables, as well as connectors for around $1.50. Check this site for info

http://www.national-tech.com/catalog/nullmodemcables.htm
http://www.trianglecables.com/nulmodad.html



Bingie
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LVL 11

Expert Comment

by:bingie
ID: 9877277
As for displaying the data, how do you want to do this? Chart form table text box?

You can VB / Excel OLE automation :

HOWTO: Create Excel Chart w/OLE Automation from Visual Basic
http://support.microsoft.com/default.aspx?scid=KB;en-us;q142387

Excel Automation:
Controlling Excel from a Visual Basic Application
http://www.msofficemag.net/features/2001/06/vba200106wf_f/vba200106wf_f.asp

You can also use the chart control:

http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q275649&ID=KB;EN-US;Q275649&sd=msdn&
http:Q_20361968.html





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by:MsLim
ID: 9879119
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LVL 11

Expert Comment

by:bingie
ID: 9998981
Any Luck??
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LVL 29

Expert Comment

by:leonstryker
ID: 10267532
No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

PAQ/No Refund
 
Please leave any comments here within the next seven days.

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!

leonstryker
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Expert Comment

by:bingie
ID: 10267685
Leon,

I think i provided more than enough information on what the asker required.

bingie
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Experts Exchange
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by:leonstryker
ID: 10267766
bingie,

I agree, but I have no way to test it and the asker did not reply to your posts.

leonstryker
EE Cleanup Volunteer
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Accepted Solution

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SpazMODic earned 0 total points
ID: 10327556
PAQed - no points refunded (of 500)

SpazMODic
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