Siemens SM1221 Digital input, 8DI, 24VDC, sink/source

Product Overview

The SIMATIC S7-1200 Digital Input Module SM 1221 provides compact 8-channel digital input monitoring with 24V DC sink/source capability specifically designed for S7-1200 controller expansion. Featuring parameterizable input delays and grouped channel configuration, this module delivers efficient signal processing for modern industrial automation systems requiring flexible I/O expansion in space-constrained installations.

Key Features

• 8 Digital Inputs: Compact input monitoring with 24V DC sink/source capability organized in groups of 2
• S7-1200 System Compatibility: Designed for seamless integration with SIMATIC S7-1200 controllers (except CPU 1211C)
• Sink/Source Input Flexibility: Universal input configuration supporting both NPN and PNP sensors and devices
• Parameterizable Input Delay: Configurable delay timing from 0.2ms to 12.8ms (adjustable in groups of 4)
• Signal Level Conversion: Converts external digital signals to internal S7-1200 controller signal levels
• Compact Design: Space-efficient form factor optimized for control cabinet installation

Technical Specifications

• I/O Configuration: 8 DI (24V DC sink/source) | Input Groups: Organized in groups of 2
• Dimensions: 88mm (W) × 109mm (H) × 60mm (D) | Weight: 0.150 kg
• Input Voltage: 24V DC (allowable range: 20.4-28.8V DC)
• Input Delay: Configurable 0.2ms to 12.8ms (groups of 4)
• Signal Characteristics: Signal "0" Max. 1mA | Signal "1" Min. 2.5mA, Typ. 4mA
• Cable Length: Up to 500m (shielded) | Protection: IP20
• Connection: Screw/spring clamp terminals | Mounting: DIN rail (35mm)

Applications & Integration

Primary Applications:

• Industrial sensor signal monitoring and processing
• Switch and pushbutton input handling for control systems
• Process status indication and monitoring
• Compact manufacturing automation with limited I/O requirements
• Building automation systems requiring digital input expansion

System Compatibility:

• Compatible with SIMATIC S7-1200 controller systems (except CPU 1211C)
• TIA Portal programming environment support
• Advanced diagnostic capabilities for system monitoring
• Modular expansion with other SM 1221/1222/1223 modules
• Fine-granular system configuration for optimized hardware costs

Quality & Compliance

• Status: Active Product (PM300) | Origin: Germany
• EAN: 6940408101913 | UPC: 887621262884
• RoHS Compliant: Since 15.03.2013 | WEEE: Take-back obligation applies
• Export Control: AL: N / ECCN: N | Product Class: A (Standard stock item, returnable)
• International Certifications: CE, UL, CSA, FM, and marine approvals
• REACH: Contains lead, lead oxide, and BPA above 0.1% w/w (safe when used as intended)

Package Contents

• 1 × SM 1221 Digital Input Module (8 DI), technical documentation, connection terminals

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• Technical Specifications