Errors in serial communication

Projects Networking, Protocols, and Devices
1

So I just wrote a basic program which communicates with a LabVIEW program on a computer over the built in serial interface on an UNO. Everything works fine, and the computer can tell the arduino what to do as long as I have the baud rate set to 9600. If I try to up the speed at all though, I get some erroneous extra characters that the arduino is reading through the serial port. In particular, there are between 1 and 4 of ASCII character 152 (an umlauted y) before the actual serial string being sent. I have never seen this before, have no idea what is going on, and haven't been able to find anything around here that addresses this.

The code checks for Serial.available to be true on each loop (I guess I could change this to a wait), then reads in using Serial.readBytesUntil, using linefeed as the terminating character. The actual string does come through, just after the extra characters.

Any help would be much appreciated.

2

1 and 4 of ASCII character 152 (an umlauted y)

More often than not, that's what happens when you read a character that hasn't arrived yet - the character is code 255, or -1.

Did you remember to check there's a character to read using "available()" before reading it?

Post your code.