I am using the Arduino Ethernet as a serial converter from RS485 to ethernet. Basically, data is being sent via RS485 from a device to the arduino + RS485 shield, which has the TX and RX for RS485 connected to pin 0 and 1 on the Arduino ethernet. Data is sent three times a second. My question is if serial buffer fills, does it get overwritten with new data regardless if data is read from the buffer using Serial.read(), or does the buffer fill up and not receive new data?
If one byte is written from the buffer, and more data is received, how is the buffer setup, is it FIFO? If so, then the new data would be added to the end of the buffer and the next byte read would be the second byte from the original set of data, assuming that the serial buffer is not overwritten if new data is received faster than the buffer can be read.