Send text file over serial port

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Hi Guys

I am trying to send a text file to a modem over the serial port using C#. I have tried the following but not seeing any data being written to the serial port.

Is my approach correct? Below are my port settings. I am using baud rate 115200, with hardware flow control on , as specified by the modem.

port.StopBits = StopBits.One;
port.Parity = Parity.None;
port.Encoding = System.Text.Encoding.GetEncoding(1252);
port.DtrEnable=true;
port.RtsEnable = true;
port.Handshake = Handshake.RequestToSend;

C#

StreamReader readtext = new StreamReader("filename.txt");
string contents = readtext.ReadToEnd();
readtext.Close();
readtext.Dispose();
byte[] WriteBuffer=new byte[contents.Length];
ASCIIEncoding enc = new System.Text.ASCIIEncoding();
WriteBuffer = enc.GetBytes(contents);
port.Write(WriteBuffer, 0,contents.Length );

Posted 21-Nov-10 3:35am

sach262

Updated 21-Nov-10 4:03am

v3

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Sandeep Mewara 21-Nov-10 9:37am

From next time please use PRF tags to format your code part. It makes the question clear and readable.

Manfred Rudolf Bihy 21-Nov-10 9:44am

The file reading stuff isn't really the interesting part. Can we have some of the bits that have to do with the construction and initialization of that port thingy.

sach262 21-Nov-10 10:07am

Hi, apologies for the incorrect format. I have updated the question with the port information

OriginalGriff 21-Nov-10 10:37am

Answer updated.

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OriginalGriff · Answer 1 · 2010-11-21T04:14:00

You can simplify your code quite a bit:

byte[] writeBuffer = File.ReadAllBytes("filename.txt");
port.Write(writeBuffer, 0, writeBuffer.Length);

http://msdn.microsoft.com/en-us/library/system.io.file.readallbytes.aspx[^]
But it won't make any difference to data coming out of the serial port.
1) Are you sure no data is being written? Why? How have you checked?
2) If you don't have any data, then:
2a) Is the port connected to a physical serial port, such as COM1? Are you checking COM1, and have you made sure that you can write to it and talk to the modem with a terminal program (hyperterminal or similar)?
2b) Have you configured Handshaking? Is so, turn it off (it is off by default)
2c) Have you enabled RTS and DTR? Try it.

If this doesn't help, edit your question and post the code fragments you use for port create and initialize - we may be able to help further when we have more info.

"Thanks Griff, I can see what is being sent and received from the serial port , using a serial port monitoring tool. Yes I have tested COM9 with hyperterminal etc. I have updated my question with the flow control settings. Note the modem specifies hardware flow control."

Good! So you genuinely have nothing coming out, but you can transmit with Hyperterminal. Try disabling the Handshake - the Modem may specify it but if it ain't there for testing it doesn't matter too much - you can re-enable it when some data is being transferred. It may be cabling between you and the modem - if you don't have the RTS/CTS and DTR/DTE pairs enabling handshake will just disable the port transmit.