The SIEMENS SM321, 16DI, DC24V (6ES7321-1BH02-0AA0) is a high-performance digital input module designed for industrial automation applications. This module supports 16 channels with a rated voltage of 24V DC and operates seamlessly within a temperature range of -20C to +60C. Featuring IP20 protection, it ensures reliable performance in controlled environments. Its compact design, measuring 40 x 125 x 120 mm, allows easy installation on DIN-rail mounts. The module utilizes a 20-pin connection method for secure interfacing and offers an operating frequency of 50/60 Hz. With a net weight of only 200 grams, it is lightweight and easy to handle. The SM321 boasts a low power loss of 3.5W and isolation capability up to 500V DC for enhanced safety. With a tolerance for up to 95% humidity, this device is ideal for automated operations requiring consistent and precise input management.

Siemens 6ES7321-1BH02-0AA0 SM 321 Digital Input Module

SIMATIC S7-300 | 16 DI | 24 V DC | Isolated | 20-Pin Connector

Supply Voltage

• Rated value (DC): 24 V

• Permissible range:

  • Lower limit: 20.4 V

  • Upper limit: 28.8 V

Input Current

• From backplane bus (5 V DC): max. 10 mA

Power Loss

• Typical: 3.5 W

Digital Inputs

• Number of digital inputs: 16

• Input type: IEC 61131 Type 1

• Simultaneously controllable inputs:

  • Horizontal installation (up to 40C / 60C): 16

  • Vertical installation (up to 40C): 16

Input Voltage

• Type: DC

• Rated value: 24 V

• Signal 0: 30 to +5 V

• Signal 1: 13 to 30 V

Input Current

• Signal 1 (typ.): 7 mA

Input Delay (24 V DC)

• Parameterizable: No

• 0 1 transition:

  • Min: 1.2 ms

  • Max: 4.8 ms

• 1 0 transition:

  • Min: 1.2 ms

  • Max: 4.8 ms

Cable Length

• Shielded: max. 1000 m

• Unshielded: max. 600 m

Encoder Compatibility

• 2-wire sensor: Yes

• Max quiescent current: 1.5 mA

Diagnostics / Alarms

• Alarms: No

• Diagnostic alarms: No

• Hardware interrupt: No

LED Indicators

• Digital input status (green): Yes

Isolation / Potential Separation

• Between channels: No

• Group-wise separation: 16 channels

• Between channels and backplane bus: Yes (Optocoupler)

• Insulation test value: 500 V DC

Connection Method

• Required front connector: 20-pin

Mechanical Data

• Width: 40 mm

• Height: 125 mm

• Depth: 120 mm

• Weight: approx. 200 g

Technical Details 

FAQs of SIEMENS SM321, 16DI, DC24V 6ES7321-1BH02-0AA0: