Serial to old reciever. Problem with the serial comunication

Projects Programming
26

I made some more testing. If I just press "return" the pioneer should respond "R". For the Putty this works constantly. I downloaded a new terminal software called Termite. That software and the Serial monitor in Arduino IDE worked in the same way - the first "return" was responded with a "R", but all following returns with "E04"

PUTTY Arduino/Termit
Return R R

Return R E04

Return R E04

Return R E04

All terminals seems to have 9600/8bit/1stopBit

What can be the cause of this?