echo serial port from SSH login

I am trying to echo my serial via SSH login (mac terminal) of my router

I have a router e1000,dd-wrt connected to an arduino via serial

I execute the following command:
root@DD-WRT:~# stty -F /dev/tts/0

and I get:

speed 115200 baud; line = 0;
intr = ^C; quit = ^\; erase = ^?; kill = ^U; eof = ^D; eol = <undef>;
eol2 = <undef>; swtch = <undef>; start = ^Q; stop = ^S; susp = ^Z; rprnt = ^R;
werase = ^W; lnext = ^V; flush = ^O; min = 1; time = 0;
-brkint -icrnl -imaxbel
-opost
-isig -icanon -echo -echoe -echok


and then:

root@DD-WRT:~# echo "Here I am" > /dev/tts/0 115200

but I get nothing. Can somebody please help?
Does the above code means that the tts/0 is the right serial because when I execute this command:

root@DD-WRT:~# dmesg | grep -i tty

I get:

Kernel command line: console=ttyS0,115200 root=1f02 rootfstype=squashfs noinitrd
console [ttyS0] enabled
serial8250: ttyS0 at MMIO 0x0 (irq = 8) is a 16550A

any hint much appreciated

Hi, but why you write dev/tts/0 115200 and not dev/ttsyS0 115200 ?