So I have a standard RS232 serial port that is looped back to itself by simply running a wire from Tx to Rx. I'm testing loopback by running echo
and cat
in two separate terminals:
cat /dev/ttyS1
echo "hi" > /dev/ttyS1
My issue is with the output. I would expect to see one "hi" come back on the terminal running cat but instead I get this:
hi
[2 newlines]
hi
[4 newlines]
hi
[8 newlines]
hi
[16 newlines]
hi
[32 newlines]
hi
...and so on until I ctrl+c cat
.
After interrupting cat, if I run it again it will not output "hi"s until I run echo a second time.
Is this normal? Any idea why I'm seeing this behavior?
Edit: By newline, I mean ASCII 0x0A
. There are no carriage returns in this output.
tip /dev/ttyS1
(~.
to exit) and tried typing data there? It should be displayed in your terminal when the wire is connected, as it receives what it has transmitted.