To add more I/O capability to the extensive options already offered by the HFP control panel, up to thirty two, sixteen channel I/O boards may be connected. The 16 channel boards may be mixed on the RS485 bus with 8 way sounder boards, 6 way sounder boards or 4 way conventional detection zone boards to provide a very flexible system of I/O to satisfy any requirement. When using a simple two wire RS485 communications protocol, these boards may be mounted locally to the control panel or distributed on a bus up to 1200 metres long by using a suitable cable. The flexibility of these boards is further enhanced by the fact that each of the channels is configurable as either an input or and output. Each channel may also be configured to produce a variety of input actions or respond to a variety of output types. All channels can contribute to, or respond to, system wide cause and effects logic. Typical uses for I/O boards include geographical LED mimic displays and plant alarm inputs