Customer display is buffering text and I need to "cat" the device to see it

I have a Posiflex customer display connected through a USB port in /dev/ttyACM0. I have used the same PC hardware, operating system and customer display in the past. However, the new customer displays I am testing now are buffering the text when I send text using the echo command.

I send the text to the screen with a echo command:

echo "Testing Screen" > /dev/ttyACM0

In this case, first it shows a “T”, if I run again the echo command, it shows “Test”, if I run it again, “Testing Sc”. If I cat the device it displays the full text at once but then I have to press Control + C.

cat /dev/ttyACM0

If I use the command “screen” it works as expected and the echo command works fine.

screen /dev/ttyACM0

stty command shows this:

stty -F /dev/ttyACM0 -a

speed 115200 baud; rows 0; columns 0; line = 0;
intr = ^C; quit = ^; erase = ^?; kill = ^U; eof = ^A; eol = <undef>;
eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
-parenb -parodd cs8 hupcl -cstopb cread -clocal -crtscts
-ignbrk -brkint ignpar -parmrk -inpck -istrip -inlcr -igncr -icrnl -ixon -ixoff
-iuclc -ixany -imaxbel -iutf8
-opost -olcuc -ocrnl -onlcr -onocr -onlret -ofill -ofdel nl0 cr0 tab0 bs0 vt0 ff0
-isig -icanon -iexten -echo -echoe -echok -echonl -noflsh -xcase -tostop -echoprt
-echoctl -echoke

Could anyone help me with this?

Source: unix

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