Hi Rod,

I found this code posted by u:


using System;
using System.Collections.Generic;
using System.Text;
using System.IO.Ports;
using System.Collections;
using log4net;
using log4net.Config;
using System.Threading;

namespace SMSdll
{
    public class Class1
    {
        private static readonly ILog logger = LogManager.GetLogger(typeof(Class1));
        static SerialPort ComPort;

        private static string data = "Not Ready.";

        private static void OpenPort()
        {
            try
            {
                ComPort = new SerialPort("COM9", 9600);
                ComPort.Open();
                logger.Info("ComPort Opened." + Environment.NewLine);
            }
            catch (Exception)
            {
                Console.WriteLine("Port not present/available.");
            }
        }


        public static bool SendSMS()
        {
            DateTime timeout = DateTime.Now.AddMinutes(5);
            try
            {
                ComPort.Write("AT+GMM\r");
                data = "";
                do
                {
                    data += ComPort.ReadExisting();
                    logger.Info(data);
                    if (DateTime.Now > timeout)
                    {
                        throw new Exception("AT Command timed out without receiving 'OK'.");
                    }
                }
                while (!data.Contains("OK"));
            }
            catch (Exception ex)
            {
                logger.Error("Sms sending failed miserably! Fix it!", ex);
                return false;
            }
            return true;
        }


        private static void ClosePort()
        {
            if (ComPort.IsOpen)
                ComPort.Close();
            logger.Info(Environment.NewLine + "ComPort Closed" + Environment.NewLine);
        }


        public static void SMSMain()
        {
            log4net.Appender.FileAppender fa = new log4net.Appender.FileAppender(new log4net.Layout.SimpleLayout(), "SMSdllTest.log", true);
            BasicConfigurator.Configure(fa);
            logger.Info("Log created on : " + System.DateTime.Now + Environment.NewLine);

            OpenPort();
            SendSMS();
            ClosePort();
        }
    }
}


My question:

 "DateTime timeout = DateTime.Now.AddMinutes(5);"

Please correct me if I'm wrong, I think the code sample that u posted, to initialize a modem and receive SMS, assumes a random time as the time needed to generate all the responses for that particular AT command. Is there any way to wait till all the responses for a command are received, without using a random response time?

Hi,
There is no need to know when the response will end as the loop will stop automatically when all the response is received. ie The 'OK' is received.

I put the timeout in just as a backstop incase there is something wrong, a way out for the loop.
In reality the response time is more immediate on the modems I am using.

I think my final code had this at one minute, 10 seconds [u]might</u> be plenty.

Also, it would be an advantage to put a few second thread sleep in between loops as this code puts the CPU in a bit of a spin if there is a problem and you have to wait for the timeout.

The five/one minute fallback should never be reached if all is going well, and the loop/process will stop as soon as the OK is received.

I am not aware of a definative way to tell in advance what response time the modem will give, and I would imagine that it will vary form modem to modem and depending on how many messages there are.
I suggest logging the datetime when you send the command and again when you receive the OK a few times to work out the most appropriate time for you.

Also, my final code had the timeout value set from the config file so it can be improved if needed.

If you improve on this code please post on the original thread as it gets a lot of hits.

Hope this helps
Rod

======================================
"They say, best men are molded out of faults,
And, for the most, become much more the better
For being a little bad."
--Shakespeare
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