Siemens
Siemens SIMATIC S7-400 SM 421 Digital Input Module - 16 DI, 24V DC, Alarm
Siemens S7-400 SM 421 digital input module, 16 DI, 24V DC, with alarm/diagnostics.
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12-Mo Warranty
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12-month warranty
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Same-day dispatch
Order by 2pm CST
Worldwide delivery
US, EU, Asia, Middle East
Veteran-owned
CAGE: 9NK75
16 Digital Inputs
24V DC Operation
0.1ms Input Delay
Alarm Capabilities
Diagnostic Functions
Optical Isolation
Product description
The Siemens SIMATIC S7-400 SM 421 module (6ES7421-7BH00-0AB0) provides 16 optically isolated digital inputs for 24V DC signals. It features a 0.1ms input delay and supports alarm and diagnostics functions, enhancing system monitoring capabilities.
This module is designed for high-speed applications within the S7-400 platform where precise timing and fault detection are critical. It's widely used in manufacturing automation, robotics, and high-performance machine control.
Stanlo Automation, your trusted veteran-owned supplier of surplus industrial automation parts, offers the Siemens 6ES7421-7BH00-0AB0. Rely on us for quality components and efficient service.
Technical specifications
| Inputs | 16 DI |
| Voltage | 24V DC |
| Delay | 0.1 ms |
| Functions | Alarm, Diagnostics |
| Isolation | Optical |
| Series | SIMATIC S7-400 SM 421 |
Common applications
High-Speed Automation
Machine Control
Process Automation
PLC Input Modules
Real-time Monitoring
Compatible systems
SIMATIC S7-400 PLC Systems
Also known as
Siemens S7-400 Diagnostic Input
SM 421 16DI 24V Alarm
6ES74217BH000AB0
Replaces / compatible with
This module replaces previous Siemens S7-400 digital input modules with similar 24V DC specifications and alarm/diagnostic features. It integrates into the S7-400 system.
Technical note
Expert tip
The 0.1ms input delay on the 6ES7421-7BH00-0AB0 is critical for applications requiring fast response times to discrete events.What happens next?
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Frequently asked questions
What diagnostic and alarm features are included with the Siemens 6ES7421-7BH00-0AB0 module?
The Siemens 6ES7421-7BH00-0AB0 module provides built-in alarm and diagnostics functions. These features allow the S7-400 system to detect input status changes, module faults, or wire breaks, enhancing system reliability and maintainability.