Is it not possible for two timer_tick events to work in parallel in reading the same data but performing different tasks?

Question

I developed a C# application for reading calls from GSM Modem. I used a timer to read the port regularly and notify me when there is a incoming call.

Now i am trying to use another timer which will write AT+CSQ -To know the signal quality, on the port and read the port for the quality value. In both the timers i used regular expressions to match and separate the data i need. Now the problem is that only my timer2 which is reading the signal quality is only working but not timer reading for incoming calls.

Timer reading signal strength:

private void tmr_sig_quality_Tick(object sender, EventArgs e)
    {
        if (port.IsOpen)
        {
            port.WriteLine("AT+CSQ");
            string s= port.ReadExisting();
            var match= Regex.Match(s,@"\+CSQ: (\d+),(\d+)");
            if (match.Success)
            {
                progressBar1.Value = int.Parse(match.Groups[1].Value);
            }

        }
    }

Timer reading incoming calls:

      private void timer1_Tick(object sender, EventArgs e)
       {
                s = port.ReadExisting();

                var match = Regex.Match(s, "RING[^\\+]*\\+CLIP:\\s*\"(?<phone>[^\"]*)\",(\\d+),\"([^\"]*)\",(\\w*),\"(\\w*)\",(\\w*)");

                if (match.Success && s.Contains("RING"))
                {
                    incall_status.Text = "Incoming Call...." + match.Groups["phone"].Value;
                    incall_status.Visible = true;
                }
        }

Why is this happening and solution please?

Answer 1

Two major problems. First is ReadExisting(), that will always return an empty string. Except when you are debugging and stepping through the code line by line. That gives the modem enough time to send the response. But this won't work when you run at full speed, you'll need to make a blocking call that ensures your program waits long enough to get all the returned characters. Use ReadLine() instead.

Second killer problem is that you are mixing commands. Your tmr_sig_quality_Tick() method is likely to read whatever timer1_Tick() was supposed to read. You'll need to re-think this approach. Something like a queue of commands that doesn't advance until the response to a command is received.