Overview
The Siemens 6ES7 322-1BH01-0AA0 SM 322 digital output module is a proven I/O expansion solution for SIMATIC S7-300 control systems. This optically isolated output module provides 16 24V DC digital outputs, each rated at 0.5A, making it suitable for driving solenoid valves, contactors, pilot lamps, and other discrete control loads. As a standard component in industrial automation installations, the module integrates seamlessly into existing S7-300 racks.
Key Features
- 16 Optically Isolated Digital Outputs — Outputs isolated in groups of 8 for noise immunity
- 24V DC Rated Load Voltage — Standard industrial control voltage with 20.4–28.8V DC operating range
- 0.5A Per Output — Maximum continuous output current per channel; 4A group limit (horizontal installation to 40°C)
- 20-Pin Front Connector — Standard M23 or M20 connector interface for field wiring
- Low Switching Frequency Support — Rated for 100 Hz with resistive loads, 0.5 Hz with inductive loads
- Compact Module Form Factor — Mounts directly to S7-300 backplane without external equipment
Technical Specifications
- Output current (signal “1”): 0.5 A nominal (0.6 A maximum, 0°C–40°C)
- Residual current (signal “0”): ≤0.5 mA maximum
- Minimum load current: 5 mA
- Group current limit (horizontal): 4 A/group up to 40°C; 3 A/group at 60°C
- Module total current (8A/module max): 8 A DC
- Supply voltage (load): 24V DC nominal (20.4–28.8V DC range)
- Cable length: 1000 m shielded, 600 m unshielded
- Switching frequency: 100 Hz resistive, 0.5 Hz inductive, 10 Hz lamp loads
- Operating temperature: 0°C to 60°C (horizontal); 0°C to 40°C (vertical installation)
- Weight: 190 g
- Connector: 20-pin front connector
- Series: SIMATIC S7-300
Typical Applications
The SM 322 is widely deployed in manufacturing automation for:
- Solenoid valve control (process automation, fluid systems)
- Motor starter interlocks and pilot light circuits
- Pneumatic / hydraulic actuator command outputs
- Discrete load switching in packaging, bottling, and assembly lines
- Building automation and facility control systems
- Machine tool control integration
Compatibility & Replacements
The 6ES7 322-1BH01-0AA0 is a legacy S7-300 module compatible with first and second generation SIMATIC S7-300 CPUs and requires a standard S7-300 expansion rack with 20-pin slot connectivity. Direct replacements include other SM 322 variants with identical pin assignments. For S7-1200/1500 system upgrades, equivalent digital output modules exist but require full rack redesign. Used units of this module are widely available and fully interchangeable with original Siemens production batches.
