# Siemens SIMATIC S7-300 SM 321 Digital Input Module 16DI 24V DC

**URL:** https://aio.lv/en/product--siemens-6es73211bh020aa0--3438827
**Data updated:** 2026-05-18 02:46 (EEST)
**Category:** Server Parts & Components
**Manufacturer:** Siemens
**Manufacturer code:** 6ES73211BH020AA0
**EAN:** 4025515051893
**Warranty:** 2 Years
**Availability:** Out of stock

## Summary description

The Siemens SIMATIC S7-300 SM 321 (6ES7321-1BH02-0AA0) is a high-performance digital input module designed for industrial automation systems. It features 16 digital inputs with a 24V DC operating voltage, ensuring reliable signal processing for PLC configurations. This robust module is essential for expanding the input capacity of S7-300 controllers, providing efficient and precise data acquisition in various manufacturing and process control environments.

## Long description

The Siemens SIMATIC S7-300 SM 321 is a high-performance digital input module engineered for seamless integration into industrial automation systems. This module provides 16 digital inputs operating at 24V DC, serving as a critical component for expanding the signal processing capabilities of S7-300 programmable logic controllers. Its robust design ensures reliable data acquisition and precise monitoring of field devices in demanding manufacturing and process control environments.
Advantages
This digital input module offers exceptional reliability and durability, which are essential for maintaining continuous operation in industrial settings. By providing 16 distinct input channels, it allows for efficient scaling of control systems, enabling users to monitor a wide range of sensors and switches simultaneously. The module is designed for easy installation within the S7-300 rack system, ensuring a compact and organized control cabinet layout while maintaining high signal integrity and fast response times for critical automation tasks.
Suitable for
Monitoring proximity switches and limit sensors
Integrating push-buttons and control panel signals
Expanding input capacity for S7-300 PLC configurations
Industrial process automation and manufacturing lines
This module may not be suitable for applications requiring high-voltage signal processing, as it is strictly designed for 24V DC inputs. Additionally, it is not intended for environments exceeding the specified operating temperature or humidity ranges defined for the S7-300 series.
Key specifications
Number of digital inputs: 16
Rated input voltage: 24V DC
Compatibility: Siemens S7-300 series
Input type: Sinking/Sourcing capability
Electrical isolation: Opto-isolated channels
To use the module, mount it onto the S7-300 mounting rail and connect it to the CPU via the backplane bus connector. Ensure that the 24V DC power supply is correctly wired to the front connector terminals. Once physically installed, configure the module within the STEP 7 or TIA Portal software environment to map the inputs to the desired memory addresses in the PLC program.
What to consider before purchase
Verify compatibility with your existing S7-300 rack and CPU
Ensure the 24V DC power supply meets the module requirements
Check the number of required input channels for your specific application
Confirm the environmental conditions of the installation site
Usage recommendations: Always ensure that the power is disconnected before installing or removing the module from the rack to prevent electrical damage. Use shielded cables for signal inputs to minimize electromagnetic interference in noisy industrial environments.

## Specifications

| Feature | Value |
|---|---|
| Weight | 0.234 kg |
| Product colour | Multicolour |
| Purpose | System power |
| Package depth | 51 mm |
| Package height | 150 mm |
| Package width | 128 mm |
| Module type | Analog |

## FAQ

### What payment options are available?

AiO.lv offers several payment methods: Bank transfer. All transactions are 100% secure and encrypted.

### Can this product be purchased for a company (with VAT)?

Yes. AiO.lv works with legal entities in Latvia and across Europe. The product price already includes VAT. For certain product categories, as well as for companies from other EU countries with a valid VAT number, a 0% VAT rate may apply. We issue the invoice immediately after the order is placed, support electronic BIS invoices, and automatically generate all necessary accounting documents. You can complete the purchase for a company online — simply select the company profile and choose bank transfer as the payment method during checkout.

### What is the warranty period?

All Siemens products come with an official 2 Years warranty. It covers all manufacturing defects and malfunctions that may occur during use. The warranty is valid at all authorized Siemens service centers and through AiO.lv

### Can the product be returned after purchase?

Yes, you can return the product within 14 days of purchase if you bought it as a consumer (not a legal entity). Returns are possible without giving any reason — the main condition is that the product retains its original appearance and full set of accessories. We will make the process as simple and convenient as possible: just contact our customer support team, and we will help you arrange the return.

### Where should I contact for warranty service?

For warranty-related questions you can contact the AiO.lv (SIA VSPRO) customer support team. More information about warranty service: https://aio.lv/en/warranty

## Image

https://aio.lv/img/cache/product/3438827/47504879_large.webp