About

Siemens 6ES7321-1BH02-0AA0 – Digital Input Module

The Siemens 6ES7321-1BH02-0AA0 is a digital input module for the SIMATIC S7-300 series of programmable logic controllers (PLCs). This module is designed to interface with binary input devices such as switches, sensors, and relays, converting their on/off signals into digital data that can be processed by the PLC to control and automate systems.

Key Features of the 6ES7321-1BH02-0AA0 (Digital Input Module):

• Digital Inputs: The module offers 16 digital input channels, allowing the PLC to read binary (on/off) signals from a variety of external field devices, such as proximity sensors, pushbuttons, limit switches, and relays.

• Input Voltage: It operates with 24V DC input signals, which is the standard voltage for most digital inputs in industrial automation systems, ensuring compatibility with a wide range of devices and field equipment.

• Fast Switching Time: The module provides fast switching times, allowing it to quickly detect changes in input status. This feature is critical for high-speed applications where input signal changes need to be processed without delay.

• LED Status Indicators: Each of the 16 digital input channels is equipped with an LED indicator that visually shows the current status of the input (whether it’s on or off). This is particularly useful for troubleshooting and monitoring the status of the system in real-time.

• Wide Input Voltage Range: The module is compatible with devices that use a wide range of 24V DC signals, ensuring flexibility in connecting to different field devices.

• Modular Integration: The 6ES7321-1BH02-0AA0 module is part of the S7-300 modular I/O system, allowing it to be easily integrated with other modules to expand the PLC’s capabilities and tailor the automation system to specific needs.

• Diagnostic Features: The module includes built-in diagnostic capabilities, which allow the system to detect faults and provide feedback on the operational health of the inputs. This is important for maintaining system reliability and minimizing downtime.  

SIMATIC S7-300 SM 321 Digital Input Module

Article No.: 6ES7321-1BH02-0AA0
Type: Digital Input Module, 16 DI, 24 V DC, Isolated

Power Supply

• Load Voltage (L+): 24 V DC

• Permissible Range: 20.4 – 28.8 V

• Current Consumption: Max. 10 mA from backplane bus

• Power Loss: Typ. 3.5 W

Digital Inputs

• Number of Inputs: 16

• Input Characteristic: IEC 61131, Type 1

• Max Controllable Inputs: 16 (horizontal/vertical, up to 60 °C)

• Input Voltage:

  • Type: DC

  • Rated: 24 V DC

  • Signal “0”: -30 to +5 V

  • Signal “1”: 13 to 30 V

• Input Current (signal “1”): Typ. 7 mA

• Input Delay:

  • “0”→“1”: 1.2 – 4.8 ms

  • “1”→“0”: 1.2 – 4.8 ms

• Cable Length:

  • Shielded: Max. 1,000 m

  • Unshielded: Max. 600 m

Encoder Support

• 2-wire sensor: Yes

• Permissible Quiescent Current (2-wire sensor): Max. 1.5 mA

Diagnostics / Status

• Alarms / Diagnostics: No

• Status Indicator LED: Yes (green)

Potential Separation & Isolation

• Between Channels: No

• Between Channels (group of 16): Yes

• Between Channels and Backplane Bus: Yes (Optocoupler)

• Isolation Tested: 500 V DC

Connection

• Front Connector: 20-pin

Dimensions & Weight

• Width × Height × Depth: 40 × 125 × 120 mm

• Weight: 200 g 

Technical Details