The Siemens 6ES7321-1BH02-0AA0 is a 16-channel digital input module designed for the SIMATIC S7-300 automation system. This module serves as a standard interface for connecting external 24V DC digital signals—such as limit switches, proximity sensors (BERO), and pushbuttons—to the PLC controller. It provides galvanic isolation between the process signals and the internal backplane bus, ensuring reliable data acquisition in industrial environments. This unit acts as a direct successor to the 6ES7321-1BH01-0AA0.
Features
16 digital inputs, isolated in groups of 16.
Rated input voltage of 24V DC.
Compatible with standard switches and two/three/four-wire proximity switches.
Compact 40mm wide module design for space-efficient DIN-rail mounting.
Opto-isolated signal processing for enhanced noise immunity.
Integrated status LEDs for clear signal state indication.
Applications
Manufacturing Automation: Monitoring machine interlocks, conveyor status, and sensor feedback.
Automotive Industry: Signal processing for robotic cells and assembly line synchronization.
Food & Beverage: Packaging line monitoring, including bottle detection and fill-level sensing.
Process Control: Tracking valve positions, pump status, and safety-related limit switch feedback.
Technical Specifications
Model
6ES7321-1BH02-0AA0
Number of Inputs
16
Rated Voltage
24V DC
Permissible Range (DC)
20.4V to 28.8V
Power Loss (typ.)
3.5W
Isolation
500V DC tested
Current Consumption (Backplane)
10mA max
Front Connector
20-pole
Installation Guidelines
Mounting: The module is designed to snap onto a standard S7-300 DIN rail. Ensure the module is securely locked into place.
Bus Connection: Always install the U-connector (bus connector) on the back of the module before mounting to establish communication with the CPU or adjacent modules.
Wiring: A 20-pin front connector is required for field wiring. Note that the connector features a mechanical coding mechanism; once keyed to this module type, it will only fit compatible units.
Handling: Observe ESD precautions when handling the module. Ensure the system power is disconnected before inserting or removing the module from the rack.
FAQ
What is the function of the 6ES7321-1BH02-0AA0?
It is a digital input module (SM 321) for the Siemens S7-300 PLC, providing 16 isolated inputs for 24V DC signals.
What are the input voltage requirements?
The rated input voltage is 24V DC. The permissible range for signal "0" is -30 to +5 V, and for signal "1" is 13 to 30 V.
Does this module require a front connector?
Yes, a 20-pin front connector is required for wiring. This connector is sold separately.
