Siemens 6ES7221-1BH32-0XB0 SIMATIC S7-1200 SM 1221 Digital Input Module 16DI 24V DC

16‑channel digital input module for S7‑1200 systems, providing sink/source 24V DC signal acquisition for sensors, switches, and field devices in industrial automation.

The Siemens 6ES7221-1BH32-0XB0 is a digital input SM 1221 expansion module for the SIMATIC S7‑1200 PLC family. It adds 16 digital input channels, configurable as sink or source (PNP/NPN) for 24V DC signals. With 500V AC isolation between channels and the backplane, software‑adjustable input delays (0.2‑12.8 ms), and an operating temperature range of –20 °C to +60 °C, the module is suited for expanding I/O capacity in factory automation, machine control, and process monitoring systems.

Applications

• Digital signal acquisition from pushbuttons, limit switches, and proximity sensors

• Expanding S7‑1200 I/O for conveyor systems, packaging machinery, and material handling

• Process monitoring with level switches, pressure switches, and photoelectric sensors

• Safety interlock and emergency stop signal capture (non‑safety rated)

• OEM machine building and retrofit projects requiring additional discrete inputs

Key Features

• 16 digital input channels (sink/source configurable, IEC 61131 Type 1 compliant)

• 24V DC rated input voltage (20.4‑28.8V DC permissible range)

• 4 mA typical input current per channel

• Software‑configurable input delay (0.2‑12.8 ms, selectable in groups of four)

• 500V AC isolation between channels and backplane

• Status LEDs for each input channel; diagnostic alarm capability

• Compact 45 mm width for space‑efficient control panel mounting

Technical Specifications

• Number of inputs: 16 (in groups of four)

• Input voltage: 24V DC rated (20.4‑28.8V DC)

• Input current: 4 mA typical per channel

• Input delay: 0.2‑12.8 ms (software configurable)

• Input characteristic: IEC 61131 Type 1

• Backplane current: 130 mA max from 5V DC backplane bus

• Power loss, typical: 2.5 W

• Cable length: 500 m shielded, 300 m unshielded

• Dimensions: 45 × 100 × 75 mm (W × H × D)

• Weight: approx. 210 g (0.21 kg)

• Protection rating: IP20

• Certifications: CE, UL, cULus, FM, KC, RCM, Marine

System Integration

• PLC Controllers: SIMATIC S7‑1200 (CPU 1212C, 1214C, 1215C, 1217C)

• Expansion: Mounts directly onto S7‑1200 CPU via side‑by‑side DIN‑rail configuration

• Configuration: TIA Portal (STEP 7 Basic or Professional)

• Wiring: 20‑pin front connector (screw‑type or spring‑type, sold separately)

Related Products

• CPU Controller: Siemens 6ES7215‑1AG40‑0XB0 CPU 1215C – paired controller

• Digital Output Module: Siemens 6ES7222‑1BH32‑0XB0 SM 1222 – output pairing

• Analog Input Module: Siemens 6ES7231‑4HD32‑0XB0 SM 1231 – mixed signal expansion

• Front Connector: Siemens 6ES7292‑1AX30‑0XA0 20‑pin screw‑type connector

PLC ERA is an independent industrial automation distributor. Products are sourced from established supply channels and inspected before shipment. International shipping available.