The DS7457i Series Single-zone Input Modules includes the DS7457i, the DS7457i-CHI, and the DS7457iF. Each model has a supervised input zone for connecting normally-open (NO) or normally-closed (NC) contacts. The DS7457i Series supervises the contacts using 47 k? end-of-line(EOL) resistors. Each model operates with compatible multiplex expansion modules and occupies one multiplex zone address on the system. The DS7457i and the DS7457i-CHI are designed for intrusion applications while the DS7457iF is designed for fire applications.