What is the role of PLC input and output modules are used in the fire?

Now the temperature sensitive smoke into intelligent coding and non-coding, coding can directly intelligent feedback signal to the host address (host needs to know where the fire occurred), the non-coding the feedback address signal can not be directly connected to an input module common practice module are capable of encoding such a host can receive address signals. For example now in the basement of temperature-sensitive non-coding common sense as long as the temperature of each partition to an input module, the host just know which partition is on the line of fire. Do not need to locate the point. The use of smoke on the ground pointing to the different needs of the specific location. Then the need for a lot of non-coding module, and therefore the need for direct feedback encoder type flue gas temperature sensation address. The same is now also have coding manual alarm button code hydrant pump start button coded telephone Some devices can not be directly input and output signals such as pressure switch damper valve flow indicator signals, etc. These can only have a current output is not coded signal. Then need to use the input plc modules, the device output power to the plc input output modules signal to the host. Output module is required when the host device host only direct linkage control output code modules, and then output power required to drive the linkage equipment.