The ELK 74 and the M120 are two-tone self-contained sirens which operate on 12 VDC. Depending on the wire the +12 VDC is applied will determine which sound is produced RED Wire = Yelp and YELLOW Wire the Steady tone. Generally speaking you would use one or the other depending on the desired sound. If you wanted both then I’d suggest using rules and a physical relay output:
Whenever Any Burg Alarm Turns ON
And NO Fire Alarm is Active
Then Turn OUTPUT 15 ON
Whenever any Fire Alarm Turns ON
Then Turn OUTPUT 15 OFF
Then Turn OUTPUT 16 ON
Whenever My Home (Area 1) Becomes Disarmed
Then Turn OUTPUT 15 OFF
Then Turn OUTPUT 16 OFF
OUTPUT 2 when selected as a Voltage Out (Globals G26) is Negative Switched rated for 12VDC at 1 AMP MAX. Output 2 is also hardcoded to be Steady Voltage for Burglar Alarm and Temporal 3 Pulsing for Fire Alarm