The SmartOne Addressable Contact Input Device (AI) is an intelligent field device with its own microprocessor, memory, and electronics necessary to interface N.O. or N.C. unpowered contacts to the ARIES^® NETLink control units. All of the electronics are contained in a high-impact polymer case, creating a very small and durable device for installation. Two types of AI’s are available: an AI/NC for interfacing to normally-closed devices and an AI/NO for interfacing to normally-open devices. The AI may be located up to 2,500 feet from the monitored device with #18 AWG wiring. An end-of-line-resistor is required for supervision of the wiring to the device.