Hi friends,
I'm trying to write/read on a device on Comm Port (RS232) but it's not working properly.
VB.NET 2005, is there somebody with a smiple example code to write a string on a port and read a returning string out of comm port input buffer (not byte after byte - it's to slow and dificult to synchronise with other events)
Thanks for any help.
Sandra
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Uday ParekhPosted Mar 17, 2006, 11:09 PM
and let me know if it works
Create an instance of CRs232 then set COM parameters before invoking the Open method
Dim moRS232 as New Rs232()
With moRs232
.Port = 1 '// Uses COM1
.BaudRate = 2400 ' // 2400 baud rate
.DataBit = 8 ‘// 8 data bits
.StopBit = Rs232.DataStopBit.StopBit_1 '// 1 Stop bit
.Parity = Rs232.DataParity.Parity_None '// No Parity
.Timeout = 500 '// 500 ms of timeout admitted to get all required bytes
End With
moRS232.Open ()
You can, optionally control the state of DTR/RTS lines after the Port is open
moRS232.Dtr = True
moRS232.Rts = True
Transmitting
The class has 2 buffers one for Tx and one for Rx, to transmit data just set the TxData property with the informations you wish to send then invoke the Tx method.
example:
moRS232.Write(txtTx.Text)
receiving data from com port
Just invoke the Rx method passing it the number of bytes you want to read from COM port, then read the Rxdata property.
example:
moRS232.Read(10) '// Gets 10 bytes from serial communication buffer
Dim sRead as String=moRs232.InputStreamString
Please note that thread is blocked for the period of time set by Timeout property and that in case the class cannot read all required bytes from COM buffer a Timeout exception is raised.
If the number of bytes to read is omitted, the class assumes 512 bytes have to be read from buffer.
The class is very simple and surely misses some error control, but as prefaced I just wanted to give you an example of what you can do with VB.Net without resorting to ocx'es or other 3rdy parties controls