Residential home fire alarms are required in all new constructed homes. The state of Texas has adopted NFPA 2019 thru ought the entire state as minimum requirement in all jurisdictions and should be enforced by all Authorities Having Jurisdiction.
Best to run smoke detector alarms on parallel 14/3 120VAC Primary DC Battery Back Up. Most professional smoke detector alarms have a relay module that can be purchased to tie in new existing AC powered. The relay will have output to wire to professional security alarm systems.
The COSMO tri detector - Smoke / Thermal / CO connected in daisy chain , series... Does not meet the NFPA 72 code requirements. This is the most common code violation in new custom homes. To meet requirements each COSMO would have to have it own COSMOD. Each COSMOD would then need to be interconnected.
Annex A Explanatory Material .23.6.2.3 This requirement is to ensure that devices without redundant pathways are not used to terminate additional equipment such that a loss of the pathway would result in more than one device failure to communicate and operate as intended. A dual port device that is used to daisy-chain additional devices without a redundant pathway would be prohibited.
NFPA 72 National Fire Alarm and Signaling Code 2022 reference
29.10.7.8.1 An open, ground fault, or short circuit of the wiring connecting input or output devices to the single or multiple-station alarms shall not prevent operation of each individual alarm.
29.11.2.2 A single fault on the interconnecting means between multiple-station alarms shall not prevent single-station operation of any of the interconnected alarms.
29.10.7.6 Where common wiring is employed for a combination system, the equipment for other than the fire and carbon monoxide alarm system shall be connected to the common wiring of the system so that short circuits, open circuits, grounds, or any fault in this equipment or interconnection between this equipment and the fire and carbon monoxide alarm system wiring does not interfere with the supervision of the fire and carbon monoxide alarm system or prevent alarm or trouble signal operation.
29.11.2.1 The interconnection of alarms shall comply with the following.
(2) In no case shall more than18 initiating devices be interconnected (of which 12 can be smoke alarms) where the interconnecting means is not supervised,