Welcome to the product page for the Siemens SM 322 relay output module, a versatile and robust component for the SIMATIC S7-300 PLC system. This 8-channel module utilizes relay outputs to switch a wide range of loads, including both 24V DC and 230V AC, at up to 2A per channel. Its electrical isolation ensures safe and reliable operation for controlling diverse actuators in your automation environment.
Overview of the SM 322 Relay Output Module
The SM 322 relay output module is a fundamental building block for many industrial control cabinets. Because it employs relay contacts, it provides exceptional flexibility for interfacing with different voltage systems, making it a go-to solution for applications where load types vary or higher voltages are present.
Key Features and Technical Specifications
This module is designed for maximum versatility and durability. Therefore, understanding its full capabilities is essential for proper application:
- Output Type: 8 Electromechanical Relay Contacts, offering universal voltage compatibility.
- Switching Capability: Can switch both 24V DC and 230V AC loads from the same module.
- Current Rating: Robust 2A per channel, suitable for contactors, solenoid valves, and motor starters.
- Isolation: Channels are electrically isolated from the backplane and from each other for enhanced safety.
- Diagnostics: Features LED status indicators for each channel to provide instant visual feedback.
- Lifetime: Designed for a high number of switching cycles under rated load, ensuring long-term reliability.

Typical Applications and Use Cases
The flexibility of this SM 322 relay output module makes it suitable for a vast array of industrial applications. For example, it is perfectly suited for:
- Controlling AC and DC contactors for motors and pumps
- Operating solenoid valves in hydraulic and pneumatic systems
- Switching industrial heating elements and lighting circuits
- Managing mixed-voltage control panels within a single PLC rack
To build a complete S7-300 PLC station, you will need a central processing unit. Browse our range of compatible S7-300 CPU modules to find the perfect match for your controller.
Why Choose a Relay Output Module?
Opting for this SM 322 relay output module provides distinct advantages in many scenarios. Firstly, its ability to switch both AC and DC loads eliminates the need for separate output modules, simplifying your design and reducing spare part inventory. Secondly, the physical isolation provided by the relay contacts offers excellent noise immunity and protects the PLC’s electronics from voltage transients on the load side. Consequently, you achieve a flexible, robust, and cost-effective solution for controlling a wide variety of industrial devices.
For detailed technical data, wiring schematics, and safety instructions, always refer to the official Siemens SM 322 manual.
Add Versatile Control to Your S7-300 System Today
In summary, the Siemens SM 322 relay output module stands out for its unparalleled flexibility and robust performance. Finally, by integrating this module into your S7-300 rack, you equip your control system with the ability to reliably interface with almost any industrial load, ensuring operational efficiency and design simplicity.