RS232 300 baud communication problem

Question

Hi I'm writing a program for communication with RS232. The device works to 96008N1 and 3007E1. If the program is used to 9600 it works properly while when I use the 300 baud it doesn't work. Are there any problems with communication at 300 baud in C#? For the reading on the RS232 I use serialport.ReadChar(). Can I use it at 300 baud? I'm usign System.IO.Ports.SerialPort as library. Thanks Gerardo

Sam Hobbs · Answer

So now you can investigate what the difference is between HyperTerminal and what you are doing. At least you know that the device and other hardware will work at 300 baud. I assume you know that 96008N1 means 9600 baud and 8 bits and no parity (error checking) and one stop bit. I am not sure what a stop bit is. And 3007E1 means 7 bits and even parity. Are you also familiar with flow control? I think there are two types of flow control; hardware and software. It is used to keep the two ends synchronized so that one end does not go too fast or slow. At 300 baud it is very easy for one end to go too fast. So be sure that the flow control is set properly. I think that Handshake is the same as flow control. I see in your code above that you have Handshake.None; that could be a problem.

gerardo tiso · Answer

For my unlucky with HyperTerminal works!

Sam Hobbs · Answer

Then it works with HyperTerminal too! Unless it does not work with HyperTerminal and then you have made a huge diagnostic leap. Assuming that C# is the problem and ignoring other possibilities is the type of problem that is often impossible to solve.

gerardo tiso · Answer

The device with VB6 application works! I have a problem only with C#!

Sam Hobbs · Answer

Did you try Deepender's suggestion? I consider it to be a logical and methodical diagnostic. See HyperTerminal Alternatives for Windows 7 if you don't have Microsoft's HyperTerminal.

Vulpes · Answer

That rules out the possibility that the driver doesn't support 300 baud and I don't think it can be a limitation with the .NET SerialPort class either as I found two other threads where 300 baud is being used (albeit with some other problems): http://stackoverflow.com/questions/7107407/communicate-with-kohler-meter-in-c http://stackoverflow.com/questions/6992530/change-baud-rate-in-c-without-closing-connection It's difficult to know what else to suggest but if you could post the VB6 code it might give us some clues.

gerardo tiso · Answer

Yes the same serial port driver.

Vulpes · Answer

Are you using the same serial port drivers on both machines?

gerardo tiso · Answer

The VB6 works on the other machine but with the same hardware.

Vulpes · Answer

Is the VB6 code working on the same machine or a different machine? If it's the same machine can you post it here so we can see if there's anything we're missing.

gerardo tiso · Answer

Nothing. From the serial I don't read 25 bytes. I'm using the HDD free serial port monitor for the monitoring the serial communication. Normally I don't have any characters on the serial. Often I have two or three bad characters.

Vulpes · Answer

The SerialPort class was rewritten for .NET and so isn't the same as the one used by VB6. I'd try replacing this bit of code: for (int i = 0; i { ricezione[i] = (byte)seriale.ReadByte(); seriale.DiscardInBuffer(); } with this: while(seriale.BytesToRead for (int i = 0; i { ricezione[i] = (byte)seriale.ReadByte(); } seriale.DiscardInBuffer();

gerardo tiso · Answer

I have tried nothing. :-(

deepender singla · Answer

try increasing serial.readtimeout();

gerardo tiso · Answer

This is the code. public void Seriale() { System.IO.Ports.SerialPort seriale = new SerialPort(); byte[] messaggio = new byte[5] ricezione = new byte[25]; seriale.BaudRate = 300; seriale.DataBits = 7; seriale.Handshake = Handshake.None; seriale.Parity = Parity.Even; seriale.StopBits = StopBits.One; seriale.PortName = COM3; seriale.ReadTimeout = 1000; seriale.Open(); seriale.Encoding = System.Text.Encoding.GetEncoding(1252); messaggio[0] = (byte)0x2F; messaggio[1] = (byte)0X3F; messaggio[2] = (byte)0x21; messaggio[3] = (byte)0x0D; messaggio[4] = (byte)0x0A; for (int i = 0; i { seriale.Write(messaggio i 1); } for (int i = 0; i { ricezione[i] = (byte)seriale.ReadByte(); seriale.DiscardInBuffer(); } } I have tried the same code in VB6 and the device works! Are there some troubles regarding to 300 baud communication in C# .NET 2010?

Vulpes · Answer

As long as the baud rate is supported by the serial driver then it should work - even if it is very low. Is an exception being thrown at 300 baud or is it simply not working at all?

deepender singla · Answer

what device are you using  i have never heard of any hardware connected serially to pc working at this baud rate  try first operating device using hyperterminal inbuilt in win xp if win 7 download it if it work use hyperterminal with baud rate 300 if device works then it will definately work with ur program al;so program have error

gerardo tiso · Answer

I must use 300 baud because the device works at this baud in one condition!

deepender singla · Answer

why do u need 300 baud rate it will be very slow  when u use 300 it give any error or you are not getting any results.