A Programmable Logic Controller, PLC , comprising: a CPU module ; and an event input module for time synchronization with another Programmable Logic Controller, PLC , when an event generated from outside is to be recorded at both PLCs , wherein the event input module comprises a first receiver , a second receiver , a memory , a controller and an interface unit , wherein the first receiver is configured to receive a signal from an outside sensor unit ; characterized in that the first receiver includes a first resistor (R1) configured to limit an input current and a second resistor (R2) configured to maintain an OFF guarantee voltage; further characterized in that the second receiver is configured to receive time information from an outside time provider , wherein the time information is an Inter-Range Instrumentation Group-B (IRIG-B) signal of an RS-485 standard; the controller configured to determine event generation information by allocating the time information received from the second receiver to an event detected through a signal received from the first receiver ; the memory configured to store the event generation information; and the interface unit configured to exchange the signal received from the controller with the CPU module of the PLC , wherein the interface unit includes a memory accessible by the CPU module and the controller , wherein the first receiver is such that the outside sensor unit is connected to one side of the first resistor (R1), and the other side of the first resistor (R1) is connected to the second resistor (R2) and a photo-coupler , wherein the photo-coupler is coupled to the controller . a CPU module ; and an event input module for time synchronization with another Programmable Logic Controller, PLC , when an event generated from outside is to be recorded at both PLCs , wherein the event input module comprises a first receiver , a second receiver , a memory , a controller and an interface unit , wherein the first receiver is configured to receive a signal from an outside sensor unit ; characterized in that the first receiver includes a first resistor (R1) configured to limit an input current and a second resistor (R2) configured to maintain an OFF guarantee voltage; further characterized in that the second receiver is configured to receive time information from an outside time provider , wherein the time information is an Inter-Range Instrumentation Group-B (IRIG-B) signal of an RS-485 standard; the controller configured to determine event generation information by allocating the time information received from the second receiver to an event detected through a signal received from the first receiver ; the memory configured to store the event generation information; and the interface unit configured to exchange the signal received from the controller with the CPU module of the PLC , wherein the interface unit includes a memory accessible by the CPU module and the controller , wherein the first receiver is such that the outside sensor unit is connected to one side of the first resistor (R1), and the other side of the first resistor (R1) is connected to the second resistor (R2) and a photo-coupler , wherein the photo-coupler is coupled to the controller . <EOS>