Programmable Logic Controller Guide: Selection, Application, and Maintenance for Engineers
PLC selection guide for engineers covering IEC 61131 compliance, Siemens, Rockwell, Schneider, ABB comparison, scan time sizing, and wiring. Shop at Stoklink.
- Part number
- 6ES7221-1BH32-0XB0
- Model no
- SM 1221, DI 16x24 V DC
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SIMATIC S7-1200Siemens 6ES7221-1BH32-0XB0 SIMATIC S7-1200 SM 1221 16x24VDC Digital Input PLC I/O Module
SIMATIC S7-1200 digital input module SM 1221, 16 DI, 24V DC sink/source, IP20.
Description
About the SM 1221, DI 16x24 V DC
About the SM 1221, DI 16x24 V DC
The Siemens 6ES7221-1BH32-0XB0 is a SIMATIC S7-1200 digital input module (SM 1221) with 16 sink/source inputs rated 24 V DC, expanding a CPU rack with additional discrete inputs. Input delay is parameterizable in groups of four from 0.2 ms to 12.8 ms, and interrupt-capable channels support event-driven program response.
Certifications & Standards
- CE
- CSA
- UL
- cULus
- FM
- RCM
- KC
- Marine Approval
Selection Notes
Grouped in fours, the 16 inputs let four independent sensor groups sit on separate ground references without cross-loading, and the parameterizable input delay (0.2 ms to 12.8 ms per group) trades noise immunity against response speed — set it short for fast interrupt inputs and longer for switch or relay contacts prone to bounce. Choose the 16 DI 24V DC module over an 8-input SM 1221 variant when the station needs headroom for future sensor additions without adding another rack slot.
Applications
Expanding S7-1200 CPU input count for discrete sensors, limit switches, and pushbuttons in machine control panels, with interrupt-capable channels for fast event capture.
Specification
Full specification
General information 1
| Product type designation | SM 1221, DI 16x24 V DC |
|---|
Supply voltage 3
| Rated value (DC) | 24 V |
|---|---|
| permissible range, lower limit (DC) | 20.4 V |
| permissible range, upper limit (DC) | 28.8 V |
Input current 2
| from backplane bus 5 V DC, max. | 130 mA |
|---|---|
| Digital inputs: from load voltage L+ (without load), max. | 4 mA; per channel |
Show all 72 specifications ↓ Show less ↑66 more values in Identification, Output voltage, Power loss, Digital inputs, Interrupts/diagnostics/status information, Potential separation, Degree and class of protection, Standards, approvals, certificates, Ambient conditions, Connection method, Mechanics/material, Dimensions, Version Classification, Logistics.
Identification 10
| Part number | 6ES7221-1BH32-0XB0 |
|---|---|
| Type designation | SM 1221, DI 16x24 V DC |
| Brand | Siemens |
| Condition | New, factory sealed |
| Source | Siemens and its authorised distributors |
| Warranty | Manufacturer warranty |
| Lifecycle status | Active, in production |
| EAN | 6940408101920 |
| ETIM class | EC001419 |
| eCl@ss | 27242204 |
Output voltage 1
| Power supply to the transmitters: present | Yes |
|---|
Power loss 1
| Power loss, typ. | 2.5 W |
|---|
Digital inputs 13
| Number of digital inputs | 16 |
|---|---|
| in groups of | 4 |
| Input characteristic curve in accordance with IEC 61131, type 1 | Yes |
| Number of simultaneously controllable inputs all mounting positions: up to 40 °C, max. horizontal installation | 16 |
| Input voltage: Rated value (DC) | 24 V |
| Input voltage: for signal "0" | 5 V DC at 1 mA |
| Input voltage: for signal "1" | 15 V DC at 2.5 mA |
| Input current: for signal "0", max. (permissible quiescent current) | 1 mA |
| Input current: for signal "1", min. | 2.5 mA |
| Input current: for signal "1", typ. | 4 mA |
| Input delay (for rated value of input voltage) for standard inputs: parameterizable for interrupt inputs | Yes; 0.2 ms, 0.4 ms, 0.8 ms, 1.6 ms, 3.2 ms, 6.4 ms and 12.8 ms, selectable in groups of four |
| Cable length: shielded, max. | 500 m |
| Cable length: unshielded, max. | 300 m |
Interrupts/diagnostics/status information 2
| Alarms: Diagnostic alarm | Yes |
|---|---|
| Diagnostics indication LED: for status of the inputs | Yes |
Potential separation 1
| Potential separation digital inputs: between the channels, in groups of | 4 |
|---|
Degree and class of protection 1
| IP degree of protection | IP20 |
|---|
Standards, approvals, certificates 13
| CE mark | Yes |
|---|---|
| CSA approval | Yes |
| UL approval | Yes |
| cULus | Yes |
| FM approval | Yes |
| RCM (formerly C-TICK) | Yes |
| KC approval | Yes |
| Marine approval | Yes |
| Ecological footprint: environmental product declaration Global warming potential | Yes |
| Ecological footprint: global warming potential, (total) [CO2 eq] | 123 kg |
| Ecological footprint: global warming potential, (during production) [CO2 eq] | 12.1 kg |
| Ecological footprint: global warming potential, (during operation) [CO2 eq] | 111 kg |
| Ecological footprint: global warming potential, (after end of life cycle) [CO2 eq] | -0.434 kg |
Ambient conditions 9
| Free fall: Fall height, max. | 0.3 m; five times, in product package |
|---|---|
| Ambient temperature during operation: min. | -20 °C |
| Ambient temperature during operation: max. | 60 °C |
| Ambient temperature during operation: permissible temperature change | 5°C to 55°C, 3°C / minute |
| Ambient temperature during storage/transportation: min. | -40 °C |
| Ambient temperature during storage/transportation: max. | 70 °C |
| Air pressure acc. to IEC 60068-2-13: Storage/transport, min. | 660 hPa |
| Air pressure acc. to IEC 60068-2-13: Storage/transport, max. | 1 080 hPa |
| Relative humidity: Operation at 25 ℃ without condensation, max. | 95 % |
Connection method 1
| required front connector | Yes |
|---|
Mechanics/material 1
| Enclosure material (front): Plastic | Yes |
|---|
Dimensions 3
| Width | 45 mm |
|---|---|
| Height | 100 mm |
| Depth | 75 mm |
Version Classification 4
| eClass | 16 27-24-22-04 |
|---|---|
| ETIM | 10 EC001419 |
| IDEA | 4 3566 |
| UNSPSC | 15 32-15-17-05 |
Logistics 6
| Net weight | 0.188 kg |
|---|---|
| Country of origin | DE |
| Shipping weight | 0.688 kg |
| Ships from | Türkiye |
| Dispatch | 13 Nov |
| Stock | In stock |
Source: manufacturer data · Last verified: 01 Nov 2026
Documents
Documents for 6ES7221-1BH32-0XB0
No documents are on file for this part yet.
Ask us for the datasheet
Certifications
Certifications and standards
- CE mark
- CSA approval
- UL approval
- cULus
- FM approval
- RCM (formerly C-TICK)
- KC approval
- Marine approval
Quick answers
Questions about the SM 1221, DI 16x24 V DC
Which supply voltage is SM 1221, DI 16x24 V DC rated for?
The rated operational voltage of SM 1221, DI 16x24 V DC is 24 V AC.
What is the HS code of SM 1221, DI 16x24 V DC for customs?
The tariff (HS) code on file for SM 1221, DI 16x24 V DC is 85389091.
What is the EAN of SM 1221, DI 16x24 V DC?
The EAN (GTIN) of SM 1221, DI 16x24 V DC is 6940408101920.
Where does SM 1221, DI 16x24 V DC ship from, and how fast?
SM 1221, DI 16x24 V DC ships from Türkiye. Shipping calculated at checkout · import duties and taxes paid on arrival. Stock items are dispatched within 1–2 business days.
Guides
Guides for PLC & controllers
What Is a Programmable Logic Controller and How Does It Work
Learn how a PLC works, including scan cycle, I/O sizing, IEC 61131-3 programming, and hardware selection for ABB, Schneider, and Siemens. Shop at Stoklink.
Main Components of a PLC System: Complete Guide for Engineers
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Reviews
Customer reviews
Series
Siemens SIMATIC S7-1200
- Brand
- Siemens
- Series
- SIMATIC S7-1200
