Key Features
Technical Specifications
General
Electrical
Digital Inputs
High-Speed Counter Performance
Filter Times
Isolation & Environmental
Certifications
Pin Assignment
The SB 1221 uses a 6-pin connector (X19) for field wiring :
Applications
The SB 1221 5 V DC is ideal for applications requiring high-speed, low-voltage digital signal acquisition:
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High-Speed Counting: Position and velocity feedback from incremental encoders
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Electronic Component Manufacturing: Signal acquisition from 5 V logic devices and sensors
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Precision Motion Control: Quadrature encoder input for servo and stepper systems
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Laboratory Equipment: Signal processing from low-voltage instrumentation
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Legacy 5 V Systems: Interfacing with TTL-level signals and older control electronics
Note: This module is not intended for standard 24 V DC industrial sensors. For 24 V DC high-speed inputs, refer to the 6ES7221-3BD30-0XB0 variant .
Key Benefits
Important Notes
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5 V DC Only: This module is rated for 5 V DC input signals. Applying 24 V DC signals will damage the module. Use the 6ES7221-3BD30-0XB0 variant for 24 V DC applications .
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Signal Board Form Factor: The SB 1221 plugs directly into the S7-1200 CPU. It is not a standalone module that mounts on a DIN rail.
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Source-Type Inputs Only: The inputs support current-sourcing (PNP/source) configurations only .
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Square Wave Requirement: For switching frequencies above 20 kHz, the digital inputs require a clean square wave signal. Minimize cable length, use high-quality shielded cable, and consider external load resistors if signal integrity issues arise .
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Cable Shielding: Always use shielded twisted pair cable with a maximum length of 50 m for reliable high-frequency performance .
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Power Supply: The module draws power from the CPU backplane (5 V DC, 40 mA). No external power supply is required for the module itself, but the field signals must be provided externally .
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TIA Portal Configuration: Configure the module in TIA Portal using the device configuration. For HSC applications, assign the appropriate HSC channels to the inputs .
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SIPLUS Variant: A conformal-coated version for extreme conditions is available as 6AG1221-3AD30-5XB0 (SIPLUS S7-1200 SB 1221) with extended temperature range of -40°C to +60°C .
FAQ
Q1: What is the primary function of the 6ES7221-3AD30-0XB0?
A: It is a SB 1221 signal board that adds 4 high-speed digital inputs to a SIMATIC S7-1200 PLC. It operates on 5 V DC and supports input frequencies up to 200 kHz, making it suitable for high-speed counting and positioning applications .
Q2: What is the difference between the 6ES7221-3AD30-0XB0 and 6ES7221-3BD30-0XB0?
A: The key difference is the input voltage: the 3AD30 variant operates on 5 V DC, while the 3BD30 variant operates on 24 V DC. Both offer 4 inputs at 200 kHz. Using the wrong voltage will damage the module .
Q3: Can this module be used for standard 24 V DC sensors?
A: No. This module is rated for 5 V DC only. For 24 V DC sensors, use the 6ES7221-3BD30-0XB0 variant instead. Applying 24 V DC to the 5 V module will cause permanent damage .
Q4: What is the maximum input frequency?
A: The maximum input frequency is 200 kHz for single-phase signals and 160 kHz for quadrature phase (encoder) signals .
Q5: Does this module require an external power supply?
A: No. The module draws power from the CPU backplane bus (5 V DC, 40 mA typical). However, the field input signals must be provided externally from your sensor or signal source .
Q6: What type of inputs does this module have?
A: The inputs are current-sourcing (source-type) only. They are designed for PNP-style signals where the input is pulled low (toward 0 V) to indicate an active state .
Q7: What is the cable length limit?
A: The maximum cable length is 50 meters using shielded twisted pair cable .
Q8: What is the power loss of this module?
A: The typical power loss is 1 W, minimizing heat generation inside the control cabinet .
Q9: What are the physical dimensions and weight?
A: The module measures 38 mm × 62 mm × 21 mm and weighs approximately 35 grams .
Q10: Is there a version for extended temperature environments?
A: Yes. The SIPLUS S7-1200 SB 1221 (article number 6AG1221-3AD30-5XB0) is a conformal-coated variant based on this module, with an extended operating temperature range of -40°C to +60°C and startup at -25°C .
