Sorry but this:

s.send("**OK!!");
label = s.match(" ","\r",250);

Does not make sense. You first send something to the device without listening to what the device replies to you. Then you send nothing to the device and you expect a response from the device.

label = s.match("**OK!!","\r",250);

makes sense, but I don't know if this is what you want.
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The command: s.send("**y8,3!!\r"); is wrong, you must not provide any \r at the end of the command string, so:
s.send("**y8,3!!"); is the right way to do it.
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If you send label = s.match("**!!","\r", 2000);

You should get back "** OK !!\r", do you get it? If you do the comm is working ok.
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Instead of hyperterminal you can use Br@y's Terminal, it's just what you need for serial communication, simple and with the right features
[Link: sites.google.com]

You should get back "** OK !!\r", do you get it? If you do the comm is