Siemens SIMATIC S7-300 Digital Input Module SM321

Description

The Siemens 6ES7321-1BL00-0AA0, also known as SM321, is a digital input module for the SIMATIC S7-300 PLC series. It features 32 optically isolated inputs designed for 24V DC operation. This module is ideal for acquiring binary control signals from sensors and switches in a wide range of industrial automation applications. Its proven reliability makes it a valuable component for maintaining and extending existing S7-300 control systems. Order now from PLC2Day for expert support and fast delivery.

Specifications

• Manufacturer: Siemens
• Product Series: SIMATIC S7-300
• Module Type: Digital Input Module SM321
• Part Number: 6ES7321-1BL00-0AA0
• Number of Inputs: 32
• Input Voltage: 24V DC
• Isolation: Optically Isolated
• Required Front Connector: 40-pin

Label Info

• Model: 1P 6ES7 321-1BL00-0AA0
• Serial Number: S C_LO473830
• Hardware Revision (E-Stand): 01

Application

This module is used in various industries including manufacturing, automotive, logistics, and process control for tasks such as machine control, signal monitoring, and interlocking safety functions within an S7-300 based system.

Country of Origin

Made in Germany.

CO2 Impact

By purchasing this pre-owned module, you contribute to the circular economy and prevent the emission of approximately 10 kg of CO2, which would have been generated during the production of a new unit. This is equivalent to the CO2 absorption of a mature tree over a full year.

Availability

This product is a readily available spare part for the phased-out S7-300 series. While no longer in active production, it is essential for the maintenance of existing installations.

FAQ

This module requires a 40-pin front connector. The Siemens part number for a compatible screw-type connector is 6ES7392-1AM00-0AA0.

No, this module is specifically designed for the SIMATIC S7-300 system or the ET 200M distributed I/O system, which uses S7-300 series modules. It is not compatible with the S7-400 backplane.

"E-Stand" refers to the hardware revision or engineering status of the module. E-Stand 01 indicates it is an early production version. While fully functional, later revisions may have had minor hardware updates or component changes.

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Last Update: Friday, March 13, 2026