Update README.md

README.md

@@ -94,7 +94,7 @@ to display the modes.
 ## Ethernet Communication
 
 Port needs to be specified manually for now, IP adresses can be set in
-command line.
+command line. 
 
 ### Issues
 If there are problems receiving packets, use the tool Wireshark to track 
@@ -104,8 +104,12 @@ Please ensure that python.exe UDP packets are not blocked in advanced firewall
 settings and create a rule to allow packets from port 2008.
 
 ## Serial Communication
-Serial communication was implemented and is tested for Windwos 10.
+Serial communication was implemented and is tested for Windwos 10 and Ubuntu 20.04.
 It requires the PySerial package installed.
+It should be noted that there are several modes for the serial communication.
+There is a fixed frame mode and a mode based on a simple DLE transport layer.
+When using the DLE transport layer, sent packets are encoded with DLE while 
+received packets need to be DLE encoded.
 
 ## Module Test
 Includes a moduel tester which sends TCs in a queue and automatically