Serial Port Drama

Hi,

I am trying to do some simple comms via C# and a serial port however all is not quite working
as I expect.

I am trying to talk to my inbuilt modem and do a ATI4 <return> and I should get
back "HDA CX11270 Soft Modem" instead I get back the string I have
just sent.

I have included the code below.

Any ideas,

Thanks,

Ward.


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO.Ports;

namespace SerialTest1
{
    class Program
    {
        static void Main(string[] args)
        {

            SerialPort sp = new SerialPort();
            sp.BaudRate = 9600;
            sp.PortName = "COM3";
            sp.DataBits = 8;
            sp.StopBits = StopBits.One;
            sp.Parity = Parity.None;
            sp.Open();
            sp.WriteLine("ATI4\r");
            string received_data = sp.ReadLine();
            sp.Close();

            // I should get back:  HDA CX11270 Soft Modem
            // but instead I get back ATI4

            Console.WriteLine("Data: {0}", received_data);
        }
    }
}

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LVL 1
whorsfallAsked:
Who is Participating?
 
vusovConnect With a Mentor Commented:
Try to convert "ATI4" string to byte array and use sp.Write method
0
 
effxCommented:
Have you tride the same command using Hyper Terminal?
0
 
whorsfallAuthor Commented:
well i am using different terminal software but it does work.
0
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effxCommented:
Try:

string received_data = Console.ReadLine();

instead of:

string received_data = sp.ReadLine();

0
 
effxCommented:
Scrub my last try:

sp.WriteLine("ATI4\r\n");

Instead of:

sp.WriteLine("ATI4\r");
0
 
whorsfallAuthor Commented:
Hi,

Thanks for your response same result

Ward
0
 
aledevCommented:
Try to put this line

sp.WriteLine("ATE0\r");

before this one

sp.WriteLine("ATI4\r");

and see what happens
0
 
aledevCommented:
If the echo of your modem is enabled, i think is normal that you read "ATI4" instead of  "HDA CX11270 Soft Modem" because the modem sends you back what you write (in this case "ATI4\r") so when you use ReadLine method it retrieves the first line in the buffer and probably the next one could be what you are looking for
Use this command for disable the echo and try again:

ATE0
0
 
whorsfallAuthor Commented:
Hi,

Ok I have made some changes and got it more succesfully working, maybee I could get an explination.

Here is the output.


Data:
HDA CX11270 Soft Modem
OK
 Length: 30


Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO.Ports;

namespace SerialTest1
{
    class Program
    {
        static void Main(string[] args)
        {

            SerialPort sp = new SerialPort();
            sp.BaudRate = 9600;
            sp.PortName = "COM3";
            sp.DataBits = 8;
            sp.StopBits = StopBits.One;
            sp.Parity = Parity.None;
            sp.Open();
            sp.WriteLine("ATI4\r");

            int bytes = sp.BytesToRead;
            string received_data = sp.ReadExisting();
            int length = received_data.Length;
            sp.Close();

            // I should get back:  HDA CX11270 Soft Modem
            // but instead I get back ATI4

            Console.WriteLine("Data: {0} Length: {1}", received_data,length);

            //Console.ReadKey();
        }
    }
}

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0
 
aledevConnect With a Mentor Commented:
when use ReadLine method look at the NewLine property and be sure that it is set to "\r" instead of "\n"
0
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