I recently decided to link two of my panels together. Pretty simple setup, just relays connected to each panel via a zone/point. Both panels have safeguards so there’s no infinite loop.
Since this picture was taken, I cleaned up the wiring and changed up the link. The 4010 can send two relays to the 4005 depending on the point activated. I also ran some SMPL programming so the relays on both panels will shut off when the fire alarm is acknowledged. Additionally, I configured the relays so each panel only gets one alarm (i.e. the 4010 only gets its own alarm, not the 4005’s relay).
Update (12/11/23):
I added my 4006 to the network, as well as notification appliances. My idea is for the 4005 to be the main panel. If an alarm occurs on the 4005, the 4010 and 4006 will also go into the alarm. If the 4006 OR 4010 go into alarm, the 4005 will also go into alarm. In other words, an alarm on the 4006 won’t trip the 4010 and vice versa.