ALLEN BRADLEY Slc Processor Module 1747-L20F /b 500 10-30VDC I/o

( Brand: Allen Bradley ), ( Manufacturer Part Number: 1747L20F ), ( Part Type: Module )

Review ALLEN BRADLEY /b Slc 500 Processor Module 10-30vdc I/o

The **Allen-Bradley 1747-L20F** is a robust and versatile **SLC 500 Processor Module**, designed to serve as the central brain of industrial automation systems requiring reliable, high-performance control within the **1747-L20 series** of programmable logic controllers (PLCs). This module operates within a **10 30V DC power supply range**, ensuring compatibility with a wide array of power sources commonly found in factory environments, from standard industrial power systems to battery-backed or emergency power setups. With a **20-point I/O capacity**, the 1747-L20F provides a compact yet flexible foundation for applications demanding efficient control over sensors, actuators, and other field devices, making it ideal for mid-sized automation tasks such as machine control, process monitoring, or discrete manufacturing systems.

Engineered for durability, the 1747-L20F features a **rugged, DIN-rail-mountable design** that withstands the demands of harsh industrial settings, including exposure to temperature fluctuations, vibration, and electromagnetic interference. Its **backplane-mounted architecture** allows seamless integration into the **1747-L20 series chassis**, offering scalability for future expansion with additional I/O modules, communication interfaces, or advanced programming capabilities. The module supports **RS-232 and RS-485 serial communication**, enabling easy integration with human-machine interfaces (HMIs), scanners, or higher-level supervisory systems, while its **compatibility with Rockwell Automation s Studio 5000 software** ensures intuitive programming, debugging, and monitoring through a user-friendly environment.

Beyond its technical specifications, the 1747-L20F excels in **reliability and efficiency**, delivering consistent performance even under demanding operational conditions. Its **low-power consumption** optimizes energy usage, reducing operational costs while maintaining peak functionality. Additionally, the module s **modular design** allows for easy replacement or upgrades, minimizing downtime and enhancing system longevity. Whether deployed in a small-scale automation project or as part of a larger control network, the 1747-L20F serves as a dependable workhorse, bridging the gap between raw industrial inputs and precise, automated outputs with unmatched precision and adaptability.

### **Pros and Cons of buying a Allen-Bradley 1747-L20F SLC 500 Processor Module (10-30V DC, 20 I/O)**

#### **Pros**

1. **Compatibility and Reliability**

The SLC 500 series, particularly the 1747-L20F, is a well-established industrial automation platform from Rockwell Automation (now part of Allen-Bradley). It is widely used in manufacturing, process control, and automation systems, ensuring a large pool of support, documentation, and spare parts. Many engineers and technicians are familiar with its programming (Ladder Logic) and architecture, reducing training time.

2. **Cost-Effective for Legacy Systems**

If you are maintaining or upgrading an existing SLC 500-based system, replacing the processor with a compatible module like the 1747-L20F can be a cost-effective solution. It avoids the need for a full system overhaul, which can be expensive in terms of both hardware and downtime.

3. **Scalability and Flexibility**

The 1747-L20F supports up to 20 I/O points, making it suitable for small to medium-sized control applications. It can be expanded with additional I/O modules (e.g., 1746-DA, 1746-AI, 1746-DI) to accommodate growing control requirements. The module also supports various communication protocols, including **DF1 (Data Highway Plus)**, **Ethernet/IP**, and **Modbus**, allowing integration with other PLCs, HMIs, or SCADA systems.

4. **Industrial-Grade Durability**

- Wide operating temperature range (-20 C to 60 C).

- Protection against electrical noise and voltage spikes.

- Rugged enclosure options for mounting in control panels or on DIN rails.

This makes it suitable for applications in manufacturing plants, oil and gas, or other demanding settings.

5. **Ease of Programming and Debugging**

The SLC 500 uses **RSLogix 500**, a user-friendly programming environment that supports Ladder Logic, Structured Text (limited), and Function Block programming. The software includes built-in debugging tools, such as **online monitoring**, **scan time analysis**, and **message logging**, which simplify troubleshooting.

6. **Availability of Second-Hand and Refurbished Units**

Due to its age (discontinued in 2005), the 1747-L20F is commonly available on the used market at a fraction of the original price. This makes it an attractive option for budget-conscious buyers, especially if you can source it from a reputable seller with warranty or testing.

7. **Backward and Forward Compatibility**

The SLC 500 can communicate with newer Allen-Bradley systems (e.g., ControlLogix, CompactLogix) via **Ethernet/IP** or **DF1**, allowing for gradual migration if needed. This flexibility is useful for businesses planning to modernize their automation infrastructure over time.

---

#### **Cons**

1. **Discontinued and End-of-Life Status**

- **No new production**: You will only find it on the used market.

- **Limited official support**: Rockwell Automation no longer provides technical support, firmware updates, or new documentation.

- **Potential obsolescence risks**: Over time, finding compatible spare parts or technicians with deep SLC 500 expertise may become difficult.

2. **Outdated Technology**

- **Lower processing power**: Slower scan times and limited memory (128K bytes of user memory).

- **Basic communication capabilities**: While it supports Ethernet/IP, its performance is not as robust as newer systems.

- **Limited programming features**: No support for advanced features like **motion control**, **high-speed counters**, or **advanced math functions** found in modern PLCs.

3. **Higher Long-Term Maintenance Costs**

- **Third-party repairs**: Finding a technician skilled in SLC 500 repair can be challenging and costly.

- **Dependence on legacy expertise**: If your team lacks experience with SLC 500, training may be required, adding to operational costs.

- **Risk of component failure**: Older electronics may degrade over time, leading to unexpected downtime.

4. **Limited I/O Expansion Options**

While the 1747-L20F supports 20 I/O points, expanding it requires using older I/O modules (e.g., 1746 series), which may also be discontinued. Newer I/O modules (e.g., 1756 series) are not compatible, forcing you to rely on legacy parts.

5. **Security Vulnerabilities**

- **Encrypted communication**.

- **Role-based access control**.

- **Regular firmware patches**.

This makes it more susceptible to cyber threats, which is a growing concern in industrial automation.

6. **Compatibility Issues with Modern Systems**

- **Additional gateways or converters**.

- **Custom programming** to ensure seamless data exchange.

This can add complexity and potential points of failure.

7. **Environmental and Compliance Risks**

Older PLCs may not meet current **industrial safety standards** (e.g., IEC 62443 for cybersecurity, or newer energy efficiency regulations). If your application requires compliance with modern standards, the SLC 500 may not be sufficient without additional safeguards.

---

### **Ending Conclusion**

The **Allen-Bradley 1747-L20F SLC 500 processor module** is a **practical choice for maintaining or upgrading legacy SLC 500 systems** where budget and compatibility are critical. It offers **reliability, wide availability, and cost-effectiveness** for applications that do not require cutting-edge features. However, its **discontinued status, outdated technology, and long-term maintenance challenges** make it a less ideal option for **new installations or future-proofing automation systems**.

If your primary goal is to **keep an existing SLC 500 system running**, the 1747-L20F is a solid replacement. If you are **starting a new project or planning long-term scalability**, investing in a **modern PLC** (e.g., Allen-Bradley **CompactLogix L32E**, **Micro850**, or **Siemens S7-1200**) would be a better long-term decision despite the higher upfront cost.

---

### **Recommendation**

- You are **replacing a failing SLC 500 processor** in an existing system.

- You have **limited budget** and need a **quick, cost-effective solution**.

- Your application **does not require advanced features** (e.g., high-speed motion, extensive networking).

- You can **source a tested/refurbished unit** from a trusted supplier.

- You are **starting a new automation project** and need **scalability, cybersecurity, or modern features**.

- Your system **requires integration with cloud, IoT, or advanced HMI/SCADA systems**.

- You anticipate **long-term maintenance challenges** due to lack of official support.

- You want to **future-proof your investment** for at least 10 years.

For **new projects**, prioritize a **modern PLC** with **Ethernet/IP, cybersecurity, and expandability**. For **legacy maintenance**, the 1747-L20F remains a **viable stopgap**, but plan for eventual migration to a supported platform.

Details:

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Allen Bradley 1747-L20F /B SLC 500 Processor Module 10-30VDC 20 I/O.

part #: 1747l20f prices

• $199.99-$367.33

specifications sensoindustria:

• brand: Allen Bradley
• mpn: 1747l20f
• part type: Module

general sensoindustria:

• condition: Used
• PLCs HMIs > PLC Peripheral Modules > PLC Input Output Modules

offer sensoindustria:

• best offers: True
• sold: 0
• options: Ship-to-home
• availability: In Stock
• quantity: 1
• started: April 8, 2026

seller sensoindustria:

• # reviews: 12494
• city: Noblesville, Indiana
• rating: 100.0%

shipping sensoindustria:

• class: Standard, One-day
• cost: $17.15
• service: USPS Ground Advantage, UPS Ground, UPS Next Day Air
• transit: 3-9 Days
• type: Calculated
• carrier: USPS, UPS

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