Description
The Siemens 6ES7221-1BH30-0XB0 is a SIMATIC S7-1200 SM 1221 digital input expansion module. It expands the physical input capacity of an S7-1200 controller by providing 14 discrete input channels. The module processes binary signals from field devices—such as limit switches, proximity sensors, and pushbuttons—and converts them into logic states for the CPU.
Commercial Terms & Availability
- Condition: New Original (Factory Sealed)
- Availability: In Stock
- Lead Time: 1–2 business days
- Warranty: 12-month comprehensive warranty
- Pricing Note: Price subject to market conditions; contact us for a firm quote.
Technical Specifications
The following table outlines the exact physical, electrical, and operational parameters for the 6ES7221-1BH30-0XB0 expansion module.
| Parameter | Value |
| Model Number | SM 1221 DI 16 x 24 V DC |
| Product ID | 6ES7221-1BH30-0XB0 |
| Number of Inputs | 16 digital inputs |
| Input Type | Type 1 (IEC 61131) |
| Connection Type | Sink/Source (M-reading or P-reading) |
| Nominal Input Voltage | 24 V DC |
| Input Voltage Range | 0 to 5 V DC (for Signal 0); 15 to 30 V DC (for Signal 1) |
| Input Current | 4 mA per channel (typical) |
| Input Delay (Filter Time) | 0.2 ms to 12.8 ms (configurable in groups of 4) |
| Galvanic Isolation | Yes (in groups of 4, 500 V AC between channels and backplane) |
| Current Consumption | 105 mA from S7-1200 backplane bus (5 V DC) |
| Power Loss | 2.5 W typical |
| Dimensions (W x H x D) | 45 mm x 100 mm x 75 mm |
Field Integration & Wiring Guidelines
Backplane Integration
The SM 1221 module mounts directly to the right side of any S7-1200 CPU via the integrated slide-out bus connector. It draws its 5 V DC logic operating power directly from the backplane bus.
- Power Budgeting: Verify the total 5 V DC current draw of all attached expansion modules does not exceed the backplane power supply capacity of your specific S7-1200 CPU (e.g., a CPU 1214C provides up to 1,600 mA on the 5 V DC bus).
Input Channel Grouping and Wiring
The 16 input channels are divided into isolated electrical groups of four. Each group shares a common return terminal (M), allowing you to mix sinking and sourcing wiring topologies across different groups on the same module if required by field sensor constraints.
- Sinking Configuration (P-reading): Connect the positive terminal (+24 V DC) to the sensor switch, and wire the switch output to the input terminal (
Ix.x). Connect the common return terminal (M) to the 0 V DC power supply reference. - Sourcing Configuration (M-reading): Connect the 0 V DC terminal to the sensor switch, and wire the switch output to the input terminal (
Ix.x). Connect the common return terminal (M) to the +24 V DC power supply reference.
Frequently Asked Questions
Q: Why is this module not detected by my S7-1200 CPU in the TIA Portal hardware configuration?
Ensure that the physical slide connector on the top right side of the adjacent module or CPU is fully pushed to the left into the SM 1221 module. This locks the hardware bus. In TIA Portal, verify that the exact part number (6ES7221-1BH30-0XB0) matches the hardware catalog entry in your project tree. If there is a mismatch between the configured hardware and the physical hardware, the CPU will generate a “Hardware component not available” diagnostic buffer error.
Q: Can this module process high-speed counter (HSC) pulses from an encoder?
No. Standard SM 1221 digital input modules have an input filter time (delay) that limits their maximum frequency response. For high-speed applications like optical encoders or pulse train monitoring, utilize the integrated high-speed inputs directly on the S7-1200 CPU, which support frequencies up to 100 kHz or higher depending on the CPU model. Alternatively, attach a dedicated high-speed counter module.
Q: What is the purpose of the configurable input delay?
The input delay (filter time) is used to filter out electrical noise or mechanical switch bounce on the field inputs. If you are experiencing phantom double-triggering from mechanical limit switches, increase the input delay value within the device configuration parameters in TIA Portal. For fast-acting electronic sensors, decrease the filter time to ensure rapid signal registration.
