C＃定期从串口读取新行

Question

Checked many pages but I still find it unanswered.

My problem is as follows. I have a device, connected over RS232 to the computer. The device is sending TWICE a second a line like this:

"*X;0;bbb;cc;d;eee;f\r\n"

The fields are fixed width numeric fields. Once every minute the 0 flag raises to 1 and the "cc" changes. This number I need then.

In the C# application, I cannot get it working. Tried to use the recieve event to get the data, but the refreshed result needs 10+ seconds to be processed. This means that 10 seconds after the flag was risen i get the result. Sometimes it takes even longer.

I tried first with RecieveEvent. I even tried to fill the buffer untill it would fill the line, but again, same result. Then I tried with Timer that invokes every 300 ms and reads a line. Still the same problem.

So my question is, how to read and process up to date data from serial port?

Answer 1

When reading, the serial port will buffer data. This will introduce a small delay (but we're talking milliseconds, not tens of seconds). Most serial device drivers will allow you to configure the buffering, too, if it's really critical.

If you call ReadLine, you could introduce more delay, as it will wait until it receives a newline before it returns any data. Are you sure that your device is sending good newlines? Use a terminal emulator program to see exactly what the device is actually sending, as device documentation is often terrible!

I would Read raw data from the port, and then parse it myself. You may have to be more careful about receiving partial packets, but you remove all the middle-men from the picture, and you can be more tolerant (eg Not caring whether or not the data has newlines in it). Start a read and then write out the data you received to the debug console and you'll soon see what your program is receiving and how often, etc. This will also show you if the delay is in the serial port or in your processing of the messages

Answer 2

You may try serialPort1.readExisting(); then try parsing the data.

Good luck!