Siemens 6ES7421-7DH00-0AB0
SM 421 digital input, 16 DI, 24 to 60 V AC/DC, interrupt and diagnostics
Read from the product label
- Maker
- Siemens
- Part no.
- 6ES7421-7DH00-0AB0
- Serial / rev.
- as printed on your unit
Image is for illustrative purposes only. Please refer to product description.
Delivery options
Siemens SIMATIC S7-400 SM 421 digital input module: 16 inputs for 24 to 60 V AC or DC, each isolated, with hardware interrupt, diagnostics and wire-break detection.
- Manufacturer
- Siemens
- Manufacturer part no.
- 6ES7421-7DH00-0AB0
- Product family
- SIMATIC S7-400 PLC CPUs, I/O and Function Modules
- Type
- Digital input module
- Category
- PLCs and I/O › Digital I/O modules
- Lifecycle
- Discontinued
- OEM successor
- Not stated
- Technical datasheet
- Data sheet
Technical specifications
- Manufacturer
- Siemens
- Manufacturer part no.
- 6ES7421-7DH00-0AB0
- Type
- Digital input module
- Application
- Digital input module
- Used with
- SIMATIC S7-400 rack
- Input current / from backplane bus 5 V DC, max.
- 150 mA
- Power loss, typ.
- 8 W; 3.5 W (24 V DC); 6.5 W (48 V DC); 8.0 W (60 V DC)
- Number of digital inputs
- 16
- Digital inputs / Input characteristic according to IEC 61131
- similar to IEC 61131-2
- Number of simultaneously controllable inputs / Number of simultaneously controllable inputs
- 16
- Input voltage / Type of input voltage
- AC/DC
- Input voltage / Rated value (UC)
- 24 V; 24 V UC to 60 V UC (47 ... 63 Hz)
- Input voltage / for signal "0"
- -6 to +6 V DC/ 0 to 5 V AC
- Input voltage / for signal "1"
- 15 to 72 V DC; -15 to -72 V DC; 15 to 60 V AC
- Input current / for signal "1", typ.
- 4 mA; 4 to 10 mA
- Input delay (for rated value of input voltage) / for standard inputs / Parameterizable
- Yes
- Input delay (for rated value of input voltage) / for standard inputs / Rated value
- 0.5 ms; 0.5 / 3 / 10 / 20 ms
- Encoder connection / Fixed current limitation for wire-break monitoring, min.
- 18 kΩ; 18 kohms: Rated voltage 24 V (15 to 35 V); 39 kohms: Rated voltage 48 V (30 to 60 V)
- Encoder connection / Fixed current limitation for wire-break monitoring, max.
- 56 kΩ; Rated voltage 60 V (50 to 72 V)
- Cable length / shielded, max.
- 1 000 m
- Cable length / unshielded, max.
- 600 m; 600 m: 3, 10, 20 ms; 100 m: 0,5 ms
- Connectable encoders / 2-wire sensor
- Yes
- Connectable encoders / 2-wire sensor / permissible quiescent current (2-wire sensor), max.
- 0.5 mA; 0.5 to 2 mA
- Interrupts/diagnostics/status information / Diagnostics function
- Yes; Parameterizable
- Alarms / Diagnostic alarm
- Yes; Parameterizable
- Alarms / Hardware interrupt
- Yes; Parameterizable
- Diagnoses / Diagnostic information readable
- Yes; possible
- Diagnoses / Wire break
- Yes; I> 0.7 mA
- Diagnostics indication LED / Status indicator digital input (green)
- Yes
- Diagnostics indication LED / Channel fault indicator F (red)
- No
Show all 38 specificationsShow fewer
- Potential separation digital inputs / between the channels
- Yes
- Potential separation digital inputs / between the channels, in groups of
- 1
- Potential separation digital inputs / between the channels and backplane bus
- Yes
- Isolation tested with
- 1 500 V AC
- Width
- 25 mm
- Height
- 290 mm
- Depth
- 210 mm
- Weight, approx.
- 600 g
Technical documents (1)
Key features
- 16 digital inputs, 24 to 60 V AC (47 to 63 Hz) or DC
- Each input isolated from the others
- Parameterizable hardware and diagnostic interrupts, wire-break detection
- Input delay settable: 0.5, 3, 10 or 20 ms
- Discontinued by Siemens on 1 October 2026
About the Siemens 6ES7421-7DH00-0AB0
The Siemens 6ES7421-7DH00-0AB0 is the SM 421 for 24 to 60 V signals, AC or DC, with every input isolated from the others. Siemens's data sheet gives signal "1" at 15 to 72 V DC of either polarity or 15 to 60 V AC, hardware and diagnostic interrupts, wire-break detection and settable input delays of 0.5 to 20 ms. SiePortal shows its phase-out announced on 1 October 2025 and its product cancellation on 1 October 2026.
What is the 6ES7421-7DH00-0AB0 used for?
It reads signals at 24, 48 or 60 V into an S7-400 CPU, for example in plants with 48 V or 60 V control circuits.
Lifecycle and successor
Discontinued.
Before you order
What to photograph or confirm so the right unit is quoted.
Check the order number on the module: 7DH00 is the 24 to 60 V diagnostic version.
Other parts in the Siemens SIMATIC S7-400 family
Listed for reference. They differ from the 6ES7421-7DH00-0AB0 in rating, supply, interface or function and are not interchangeable with it unless Siemens says so. Match the part number on your unit.
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|---|---|---|---|---|---|
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