16-channel 24 VDC input module for S7-1200 G2
The 6ES7221-1BH50-0XB0 is a SM 1221 digital input module that brings 16 sink/source inputs at 24 V DC to a SIMATIC S7-1200 G2 system. It is the standard-density digital input slice for that platform — no fieldbus slice separation needed; it snaps onto the CPU rail and communicates over the backplane bus. Each channel accepts either sinking (PNP) or sourcing (NPN) field devices depending on how the common rail is wired. The 24 V DC nominal level matches the standard control voltage in industrial panels, so no level translator sits between the sensor and the PLC.
What the 16-channel count means on the rail
Sixteen inputs in a single module saves one slot compared to running two 8-channel modules. The packaging dimensions are 150 x 47 x 110 mm — that 47 mm width is two standard DIN-rail module widths, so it wires up clean without crowding the adjacent terminals. The sink/source wiring flexibility means you can land both NPN proximity sensors and PNP photoelectric eyes on the same module without rewiring the commons — just group the commons by type and land them on the appropriate M or L+ bus.