Product Description
6ES7421-1FH20-0AA0 is a digital input module for the SIMATIC S7-400 PLC system. It offers 16 isolated channels for AC/DC signals. This SM 421 unit handles high voltages up to 264 V AC/DC. It is ideal for industrial environments requiring robust signal acquisition. The module meets IEC 61131 Type 2 standards for reliable performance.
Key features: galvanic isolation per group, high noise immunity, and flexible encoder support. It is a trusted choice for critical automation tasks. The compact 25 mm width saves valuable rack space. This module ensures stable operation in harsh factory conditions.
Technical Specifications
| Brand | Siemens |
| Model | 6ES7421-1FH20-0AA0 |
| Series | SIMATIC S7-400 |
| Type | Digital Input SM 421 |
| Inputs | 16 isolated, AC/DC |
| Rated Voltage (UC) | 120/230 V AC (47-63 Hz) |
| Signal “0” Range | 0-40 V AC / -40 to +40 V DC |
| Signal “1” Range | 74-264 V AC; 80-264 V DC, -80 to -264 V DC |
| Input Current (typ.) | 10 mA AC (120V), 14 mA AC (230V); 1.8-2 mA DC |
| Quiescent Current (max) | AC: 6 mA; DC: 2 mA |
| Input Delay (0→1) | AC 20 ms / DC 15 ms (max) |
| Input Delay (1→0) | AC 30 ms / DC 25 ms (max) |
| Backplane Current | 5 V DC, max 80 mA |
| Power Loss (typ.) | 12 W |
| Cable Length (shielded) | 1000 m |
| Cable Length (unshielded) | 600 m |
| 2-wire sensor support | Yes, max 5 mA quiescent |
| Isolation (channels) | Galvanic, groups of 4 |
| Isolation test | 1500 V AC |
| Status LED | Green per channel |
| Dimensions (WxHxD) | 25 x 290 x 210 mm |
| Weight | approx. 650 g |
Environmental & Diagnostics
- Temperature range: 0°C to 60°C (operating), -40°C to 70°C (storage)
- Humidity: 5% to 95% RH, non-condensing
- Noise immunity: Excellent against high-voltage transients
- Diagnostics: No integrated diagnostics (status LEDs only)
- Status display: Green LED for each input channel
Installation & Commissioning
- Easy mounting: Snap onto S7-400 rack. No tools required.
- Wiring: Front connector with screw terminals (included).
- Configuration: Automatic detection by CPU. No address switches.
- Maintenance: LED indication for quick fault tracing.
- Compatibility: Works with all S7-400 CPUs and ET200M.
Certifications & Standards
- IEC 61131 Type 2 – compliant input characteristic
- CE, UL, CSA – approved for industrial use
- RoHS – compliant
- Shipment: FedEx, DHL, UPS (worldwide)
Package Contents
- 1x SM 421 module – 6ES7421-1FH20-0AA0
- 1x Front connector (screw type)
- 1x Labeling strip
- 1x Manual (digital download)
Warranty & Support
- 12-month warranty – covers defects in materials and workmanship.
- Technical verification before shipment ensures full functionality.
- Global support for obsolete control systems.
- Fast delivery: via FedEx, UPS, or DHL (tracking provided).
Why Buy From Oiltech Controls?
- 15+ years in industrial automation spares.
- Global shipping – fast and reliable logistics.
- Tested surplus and refurbished options with full function check.
- 12-month warranty and technical support.
- Verification by experienced engineers before dispatch.
- Support for legacy and discontinued PLC systems.
Typical Applications
- High-voltage AC/DC signal monitoring in power plants.
- Industrial motor control feedback (230V AC).
- Level and pressure sensors in harsh environments.
- Emergency stop circuits and safety interlocks.
- Retrofit projects for obsolete S7-400 systems.
Frequently Asked Questions
- Can it handle 120V DC? Yes, rated for 80-264 V DC.
- What is the max cable length? 1000 m shielded, 600 m unshielded.
- Does it support 2-wire sensors? Yes, max 5 mA quiescent.
- Is it compatible with ET200M? Yes, works as remote I/O.
- What is the isolation voltage? 1500 V AC tested.
Contact Information
Email: info@oiltechcontrols.com
WhatsApp: +86 158 8020 0923
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Original Source: https://www.oiltechcontrols.com/
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