Problems with connecting to a USB serial port using MacOS

Hi, all,

Now, I have a a z-wave device USB controller, and a z-wave device. I want to use my computer to send commands to the USB controller , and then USB controller can control that z-wave device....Im sure that my USB controller has been already configured on my laptop (macBook), and the device is in the z-wave network.

I use the codes below:

s1=serial('/dev/tty.SLAB_USBtoUART','BaudRate',9600,'Parity','none','Stopbits',1,'Terminator','CR','Databits',8); 

fopen(s1);

command='N,OFF';% switch off the z-wave device..

fprintf(s1,command);

fclose(s1);

BUT.....nothing happened.....the device is still working.. not switched off...

Any idea???

Thank you soooo much!!!!