Siemens 505-4208-A Industrial Automation Module

Siemens PPX:505-4208-A Digital Input Module is an eight-channel AC input card for the SIMATIC 505 family, designed to read 100–115 VAC signals with 47–63 Hz operation. It draws about 2.0 W from the base and provides eight discrete inputs to connect AC-powered sensors such as limit switches or relays. On input, the module expects a minimum ON voltage of 79 VAC and a maximum ON voltage of 132 VAC, with ON current specified between 4 and 15 mA and a maximum OFF current around 1.5 mA; signal propagation through the module introduces a delay of roughly 6–30 ms. This is a single-wide PPX module that plugs into a 505-series backplane, enabling expansion of legacy automation setups. The part number 505-4208-A identifies the eight-channel AC input capability, making it suitable for applications requiring reliable 110 V AC sensing in industrial machinery, controls, and safety interlock circuits.