It looks like you have two totally separate fire alarm systems: the EST system and the FM200 system. Each one has its own detection system, horns and strobes, and actions that they take when they have an alarm.
The EST system doesn't tell the FM200 system to do anything; when there's an alarm on the EST system, the FM200 system doesn't do anything or display anything at all. However, the FM200 system tells the EST system to do things. When there's a red-light alarm on the FM200 system, the EST system goes into a red-light alarm; when there's a yellow-light trouble (fault) on the FM200 system, the EST system goes into a yellow-light supervisory alarm.
The SIGA-CT2 module is a dual input module. One input should be programmed as an alarm input to the EST and one input should be programmed as a supervisory input (like a tamper on the sprinkler system).
The wiring for the inputs is like a waterflow switch and a sprinkler tamper switch and is shown on the installation sheet that comes with the module.