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Siemens 6ES7321-1BL00-0AA0 SIMATIC S7-300 Digital Input SM 321
The Siemens 6ES7321-1BL00-0AA0 is a high-density digital input module for the SIMATIC S7-300 automation system. It gives you 32 isolated 24V DC digital inputs on a single module, arranged in 4 groups of 8, making it a solid choice when you need to bring a lot of field signals, pushbuttons, limit switches, sensors, into your PLC without using up multiple slots. It’s officially listed by Siemens as a spare part, and it works in both centralized S7-300 racks and distributed ET 200M I/O stations.
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Categories: PLC I/O Modules
Description
The Siemens SIMATIC S7-300 SM 321 digital input module provides 32 digital input channels for sensing 24 V DC field signals. A signal of 13–30 V is recognized as logic 1, while −30 to +5 V is recognized as logic 0, with typical input current of approximately 7 mA at the rated signal level. The module follows IEC 61131 Type 1 input characteristics and supports 2-wire sensors with a maximum permissible quiescent current of 1.5 mA.
The module provides 1.2–4.8 ms input delay for both signal transitions and supports up to 32 simultaneously controlled inputs depending on installation position and ambient temperature. The inputs are electrically isolated from the backplane bus and isolated from one another in groups of 16. Siemens specifies no diagnostic functions or interrupts for this standard SM 321 module, while each input has its own green status LED.
QTech Safety is a leading supplier of Siemens 6ES7321-1BL00-0AA0 SIMATIC S7-300 Digital Input SM 321 in Ireland, offering competitive prices and fast worldwide shipping across United Kingdom (UK), Germany, France, Italy, Spain, United States USA, Canada, Mexico, and Western Australia (Perth). Buy Siemens PLC I/O Modules from one of Ireland’s most trusted industrial safety equipment suppliers.
Features of Siemens 6ES7321-1BL00-0AA0 SIMATIC S7-300 Digital Input SM 321
- SIMATIC S7-300 SM 321 digital input module for industrial automation systems.
- Provides 32 digital inputs for 24 V DC signals.
- Uses IEC 61131 Type 1 input characteristics.
- Recognizes 13–30 V as a logic 1 signal.
- Recognizes −30 to +5 V as a logic 0 signal.
- Typical input current is 7 mA for a logic 1 signal.
- Supports 2-wire sensors with up to 1.5 mA permissible quiescent current.
- Provides input delay of 1.2–4.8 ms for both transitions.
- Supports up to 32 simultaneously controlled inputs at suitable operating conditions.
- Provides electrical isolation from the S7-300 backplane bus.
- Inputs are isolated from one another in groups of 16.
- Provides a green status LED for each digital input.
- Requires a 40-pin front connector.
- Supports shielded cable lengths up to 1,000 m.
- Requires no dedicated diagnostic functions or hardware interrupts.
- Compact S7-300 module measuring 40 × 125 × 120 mm.
Technical Specifications of Siemens 6ES7321-1BL00-0AA0
- Product type: SM 321 digital input
- Product family: SM 321 digital input modules
- Number of digital inputs: 32
- Input voltage type: DC
- Rated input voltage: 24 V DC
- Signal “1” input voltage: 13–30 V
- Signal “0” input voltage: −30 to +5 V
- Typical input current for signal “1”: 7 mA
- Input characteristic: IEC 61131 Type 1
- Input delay, 0 to 1: 1.2–4.8 ms
- Input delay, 1 to 0: 1.2–4.8 ms
- Input delay parameterizable: No
- 2-wire sensor support: Yes
- Maximum quiescent current for 2-wire sensor: 1.5 mA
- Maximum unshielded cable length: 600 m
- Maximum shielded cable length: 1,000 m
- Number of simultaneously controlled inputs, horizontal up to 40°C: 32
- Number of simultaneously controlled inputs, horizontal up to 60°C: 16
- Number of simultaneously controlled inputs, vertical up to 40°C: 32
- Supply voltage: 24 V DC
- Permissible supply voltage range: 20.4–28.8 V DC
- Reverse polarity protection: Yes
- Current consumption from backplane bus: 15 mA max.
- Power loss: 6.5 W typical
- Diagnostic function: No
- Diagnostic alarm: No
- Hardware interrupt: No
- Status indication: Green LED per input
- Isolation from backplane bus: Yes, optocoupler
- Isolation between input channels: Yes, in groups of 16
- Isolation test voltage: 500 V DC
- Permissible potential difference between circuits: 75 V DC / 60 V AC
- Required front connector: 40-pin
- Isochronous operation: No
- Dimensions (W × H × D): 40 × 125 × 120 mm
- Weight: Approx. 260 g
Applications
The Siemens 6ES7321-1BL00-0AA0 SIMATIC S7-300 Digital Input SM 321 is commonly used in:
- Digital signal acquisition in SIMATIC S7-300 control systems
- Monitoring 24 V DC sensors and switches
- Machine automation and control panels
- Industrial interlocking and status monitoring
- High-density digital input applications requiring 32 channels
- Legacy S7-300 installations requiring isolated digital inputs
Why Choose QTech Safety?
At QTech Safety, we’re more than just a safety supplier we’re your trusted partner in workplace protection and compliance.
Here’s why companies across UK and Ireland (EU) choose us for safety products and training:
- Comprehensive Range of Safety Equipment:
From gas detection and PPE to industrial safety tools, we offer one of the widest selections of trusted brands all at competitive Irish market prices. - Test & Measurement Instruments You Can Trust:
We supply a wide range of test and measurement instruments from the most leading and trusted brands, including industrial sensors, multimeters, oscilloscopes, accelerometers, proximity sensors, and other advanced measurement tools to support accurate diagnostics, condition monitoring, calibration, and maintenance applications. - Expert Health & Safety Training:
We provide professional health and safety training programmes designed to help your workforce stay compliant and confident on the job. - Fast, Reliable Delivery Worldwide:
Whether you’re in Texas United States or Perth Western Australia, our fast delivery service ensures you get your safety equipment quickly and efficiently. - Trusted by European Businesses:
We’re proud to support industries across Europe (UK) with certified safety solutions, expert advice, and responsive customer service.
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At QTech Safety, we supply industrial sensors and instrumentation across Ireland, offering fast and reliable worldwide delivery. Through strong global logistics partnerships, we ensure efficient shipping and professional support for customers in Europe, North America, and Australia.
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