[Selecting Baud Rate for PCOM]

This is exactly what I was looking for. I have it implemented just the way you suggest and it appears to be working very good. Thank You!!

[Selecting Baud Rate for PCOM]

Hello,

 

I have a .net application that connects to a 570 via RS-232 using System.IO.Ports.SerialPort. Normally, it will connect. However, when playing with different baud rates, it sometimes does not connect until I connect the same PC with any Unitronics software (Visilogic or Remote Operator). My question is this:

 

With VIsilogic, it appears that you can define the baud rate to anything in the connection properties and it always connects. How does the controller adapt accordingly? I think "out of the box", the rate is set to 115200.

 

If I change my application to 57600, it failes to connect. But, if I connect using Visilogic @ 57600 it works. I go back to my application and then it works. I am trying to determine what Visilogic is doing that I am not. My connection looks like this:

 

                    // Connect to the PLC

                    try

                    {

                        string comPort = Properties.Settings.Default.CommPort;

                        int comBdRate = Properties.Settings.Default.CommBdRate;

                        int comTimeOut = Properties.Settings.Default.CommTimeOut;

                        _serialPort.PortName = comPort;

                        _serialPort.BaudRate = comBdRate;

                        _serialPort.DataBits = 8;

                        _serialPort.Parity = Parity.None;

                        _serialPort.Handshake = Handshake.None;

                        _serialPort.ReadTimeout = comTimeOut;

                        _serialPort.NewLine = "\r";

                        _serialPort.Open();

                    }

                    catch (Exception)

                    {

                        // Disconnect from the PLC

                        _serialPort.Close();

                    }

 

Once this executes, I begin sending PCOM commands:

 

            try

            {

                // Send the message out the serial port.

                _serialPort.DiscardInBuffer();

                _serialPort.WriteLine(message);

                // Verify the message was received, catch the timeout

                string response = _serialPort.ReadTo("/A00SBF5");

                if (response == "/A00SBF5")

                {

                    //do nothing, success!!

                }

            }

            catch (Exception)

            {

                _connectionLost = true;

                _serialPort.Close();

                return -1;

            }

 

The _serialPort.ReadTo() catches the timeout (default 1 sec). When that occurs, we assume we lost the connection. Is there something I should be doing to prime the port first?

 

Thanks!