C#/.NET wrapper for serial port WIN32 Comm API

Question

I am looking for a way to have as much control as it is possible over serial port in my c# application. The problem is that I need to communicate with a device that has no documentation except for an old c++ program written to control it. I've tried to use SerialPort class to communicate with the device but its behaviour is quite odd (I have to repeat some of the commands, some other commands dont work at all). I would like to copy that unmanaged program's behaviour, however it seems to be impossible with serialport class, as it does not provide access to low-level functions and structures like DCB for example.

Are there any low-level wrappers for serial communication available for .net? Maybe i could use reflection to manipulate serialport innacessible members at runtime?

Answer 1

Unfortunetely, the SerialPort class is an incomplete wrapper. I have found the only way to gain access to the underlying DCB is through reflection.

The only other option would be to re-write SerialPort and make it complete. I have not seen any such implementation freely available (yet).

Here is an example where I used reflection to gain access to RTS_CONTROL_TOGGLE: http://social.msdn.microsoft.com/Forums/en-US/csharpgeneral/thread/45a89532-b01c-4ef8-aa46-532882cec004

Answer 2

The SerialPort class is a very thin wrapper around the Win32 serial port API, hard to see how another wrapper could improve your life. There are wrappers available from the .NET 1.x days, it didn't support serial ports. Here is one from MSDN magazine.

But you're just as likely to have the same problems. One way that written commands could get lost is by the device throwing away received bytes (or losing them) when it has turned off the RTS signal off. You fix that by setting the Handshake property to RequestToSend.

One way that things can go wrong with reading commands is to get the Read() call wrong. It will return an arbitrary number of bytes, as many as are available in the receive buffer. Pay attention to the return value, it tells you how many bytes were actually read. The only guarantee is that it will at least be 1 and never more than count.

The SysInternals' PortMon utility can help you troubleshoot communications, it gives you a raw view of what the device driver sees. Compare with, say, Hyperterminal or another known-good program.

Answer 3

You may be able to copy the old C++ code into a managed C++ class, which you could then use just like any normal .NET class from your C# code. This may be the fastest way to reach your goal.