Format : S,<ts>,<port_num>,<name>,<value>,<rc>,<err>
Example : S,1366227448.192,5,-m,166.376,0,
Example : S,946684811.244,3,frequency,151.496,0,
Example : S,946684811.249,3,gain_mode,1,0,
Example : S,946684811.25,3,tuner_gain,40.2,0,
Example : S,946684811.25,3,test_mode,0,0,
Example : S,946684811.251,3,agc_mode,0,0,