hi all; 
iam working at programming parallax servo controller 16 channel #28830
iam trying many ways to send commands to it, and i tried to see pwm signal at oscillscope but there is nothing
any help plz. 
You need to post links to the hardware, not vague descriptions of the hardware.
You need to post the code you tried to use, not some vague description of it.
That product is now eol and some of the links to the product maybe broken.
Have a look at this thread and see if it helps.
I found this by searching the Parallax web site.