Are the Powerhorns new?
The older ones where measurably louder.
http://forums.x10.com/index.php?PHPSESSID=1k7sk66r4lgsr7eat23281t3a4&topic=22928.90Also if they are later revision ones. They may start then stop then start again on an alarm.
The SC1200 sends the HouseCode/Unit Code &House Code/Unit Code+1 On
The the sequence again with an Off.
Panic Alarm from KR32A:
R: B1 - 4:28:40 PM 2/28/2011
R: B2 - 4:28:40 PM 2/28/2011
R: BOn - 4:28:41 PM 2/28/2011
R: B1 - 4:28:43 PM 2/28/2011
R: B2 - 4:28:43 PM 2/28/2011
R: BOff - 4:28:44 PM 2/28/2011
R: B1 - 4:28:45 PM 2/28/2011
R: B2 - 4:28:46 PM 2/28/2011
R: BOn - 4:28:46 PM 2/28/2011
R: B1 - 4:28:47 PM 2/28/2011
R: B2 - 4:28:48 PM 2/28/2011
R: BOff - 4:28:48 PM 2/28/2011
R: B1 - 4:28:49 PM 2/28/2011
R: B2 - 4:28:49 PM 2/28/2011
R: BOn - 4:28:50 PM 2/28/2011
R: B1 - 4:28:51 PM 2/28/2011
R: B2 - 4:28:51 PM 2/28/2011
R: BOff - 4:28:52 PM 2/28/2011