Siemens Simatic S7-1200 G2: SM 1221 Digital input, 16DI, 24VDC sink/source Part number 6ES7221-1BH50-0XB0

Product Overview

The Siemens SIMATIC S7-1200 G2 SM 1221 digital input module (6ES7221-1BH50-0XB0) is a compact and reliable input expansion module designed for automation systems. It provides 16 digital inputs at 24 V DC, configurable for both sinking and sourcing operations, enabling precise signal acquisition for industrial applications. This module integrates seamlessly into the SIMATIC S7-1200 series, offering robust performance, high signal reliability, and easy configuration through TIA Portal.

Key Features

• Input Channels: 16 digital inputs for flexible signal acquisition
• Voltage Rating: 24 V DC (sinking or sourcing)
• Input Delay: Configurable from 0.2 ms to 12.8 ms for optimized response
• Cable Length: Up to 300 m (unshielded) or 500 m (shielded)
• Diagnostics: Integrated input status indication for easy troubleshooting
• Mounting: Standard DIN-rail installation for space-saving integration
• Compatibility: Fully compatible with SIMATIC S7-1200 CPUs and TIA Portal engineering
• Protection: IP20 for safe operation in control cabinets

Technical Specifications

• Product Series: SIMATIC S7-1200 G2 – SM 1221 Digital Input Module
• Input Channels: 16 (24 V DC)
• Input Type: Sink/Source
• Input Current (per channel): 4.1 mA (typical)
• Power Loss: Approx. 3.2 W
• Backplane Bus Current: Max. 90 mA at 5 V DC
• Input Delay (parameterizable): 0.2 – 12.8 ms
• Cable Length (unshielded): Up to 300 m
• Cable Length (shielded): Up to 500 m
• Mounting Type: DIN-rail (EN 60715)
• Protection Class: IP20
• Operating Temperature: –20 °C to +60 °C
• Storage Temperature: –40 °C to +70 °C
• Dimensions (W × H × D): 45 mm × 100 mm × 75 mm
• Weight: Approx. 0.21 kg
• Country of Origin: China

Compliance & Certifications

• CE Marking: Complies with EU Machinery and Low Voltage Directives
• UL / CSA: Certified for industrial control equipment
• RoHS Compliant: Free of restricted hazardous substances
• WEEE Directive: Take-back obligations apply where required
• Export Control: ECCN EAR99H / AL N
• Product Classification: Industrial automation input module (Class A)

Applications

Ideal for automation systems, control panels, and distributed I/O applications that require reliable digital signal acquisition. Commonly used in process control, machine building, and factory automation to interface sensors, switches, and signal devices with the SIMATIC S7-1200 PLC platform.