Product Overview
Technical Summary
| Parameter | Value |
|---|---|
| Module type | SIMATIC S7-400 SM 421 isolated digital input |
| Digital inputs | 16 |
| Input voltage | AC/DC; 24 V UC to 60 V UC (47 … 63 Hz) |
| Signal "0" | -6 to +6 V DC/ 0 to 5 V AC |
| Signal "1" | 15 to 72 V DC; -15 to -72 V DC; 15 to 60 V AC |
| Simultaneously controllable inputs | 16 |
| Input current from backplane bus | 5 V DC, max. 150 mA |
| Power loss | 8 W; 3.5 W (24 V DC); 6.5 W (48 V DC); 8.0 W (60 V DC) |
| Diagnostics | Parameterizable diagnostics, diagnostic alarm, and hardware interrupt |
| Product lifecycle | Announcement of product phase-out |
Applications
- Digital signal acquisition: Acquires digital signals through 16 isolated digital inputs.
- Wire-break monitoring: Supports wire-break monitoring through fixed current limitation and wire-break diagnosis.
- Diagnostic alarm handling: Supports parameterizable diagnostic alarms and hardware interrupts.
Key Features
- 16 isolated digital inputs: The SM 421 module has 16 isolated digital inputs, with all 16 inputs simultaneously controllable.
- AC/DC input voltage: Input voltage is AC/DC, with a rated value of 24 V UC to 60 V UC (47 … 63 Hz).
- Signal input ranges: Signal "0": -6 to +6 V DC/ 0 to 5 V AC. Signal "1": 15 to 72 V DC; -15 to -72 V DC; 15 to 60 V AC.
- Diagnostics and alarms: The module has parameterizable diagnostics, diagnostic alarms, hardware interrupts, readable diagnostic information, and wire-break detection at I> 0.7 mA.
- Encoder connection: It supports 2-wire sensors and shielded cables up to 1 000 m. Permissible quiescent current for a 2-wire sensor is 0.5 mA; 0.5 to 2 mA.
- Isolation and dimensions: Digital inputs are isolated between channels and between the channels and backplane bus. Isolation is tested with 1 500 V AC; dimensions are 25 mm × 290 mm × 210 mm.
Frequently Asked Questions
1. How many digital inputs does the 6ES7421-7DH00-0AB0 have?
It has 16 isolated digital inputs, and all 16 inputs are simultaneously controllable.
2. What input voltage ranges does this module support?
The input voltage is AC/DC. The rated value is 24 V UC to 60 V UC (47 … 63 Hz); signal "0" is -6 to +6 V DC/ 0 to 5 V AC, and signal "1" is 15 to 72 V DC; -15 to -72 V DC; 15 to 60 V AC.
3. What diagnostics and alarm functions are available?
It has parameterizable diagnostics, diagnostic alarms, hardware interrupts, readable diagnostic information, and wire-break detection at I> 0.7 mA.
