Description
The Reliance Electric 57412 represents a pivotal piece of industrial control history, being the processor module for the renowned AutoMate 15 and AutoMate 20 programmable logic controllers (PLCs). Developed by Reliance Electric, a name synonymous with robust industrial machinery and later integrated into the Rockwell Automation portfolio, this module was engineered for reliability and deterministic control in demanding environments. The Reliance Electric 57412 processor is the central brain of the system, executing ladder logic programs to automate machinery, control processes, and manage discrete I/O with high-speed precision. As a cornerstone of many legacy automation systems, the value of the Reliance Electric 57412 extends beyond its original function; it is a critical spare part for maintaining operational continuity in factories where system upgrades are not immediately feasible. Ensuring a reliable supply of this module is essential for minimizing downtime in aging yet vital control systems.

57412 RELIANCE
Technical Specifications
| Parameter Name | Parameter Value |
| Product Model | 57412 |
| Manufacturer | Reliance Electric (now part of Rockwell Automation) |
| Product Type | PLC Processor Module |
| For Use In | AutoMate 15, AutoMate 20 PLC Systems |
| Memory Type | CMOS RAM (typically backed by lithium battery) |
| I/O Capacity | Supports up to 128 I/O points (system dependent) |
| Programming Language | Relay Ladder Logic |
| Communication | Proprietary AutoMate programming port |
| Operating Voltage | 5 VDC (provided by system power supply) |
| Operating Temperature | 0 to 60 °C (32 to 140 °F) |
| Storage Temperature | -40 to 85 °C (-40 to 185 °F) |
| Relative Humidity | 5 to 95% (non-condensing) |
Main Features and Advantages
The Reliance Electric 57412 processor module is renowned for its ruggedized design and deterministic performance. Its primary advantage lies in its exceptional reliability, built to withstand the electrical noise, vibration, and temperature fluctuations common on factory floors, which ensures long-term system stability for critical processes. A key feature is its efficient execution of ladder logic, providing predictable scan times essential for applications requiring precise timing and sequencing. The module was designed for straightforward integration within its native AutoMate ecosystem, allowing for seamless connection with a wide range of Reliance digital and analog I/O modules. While modern in its time, the 57412 is characterized by its simplicity and durability, making it a trusted component that kept machinery running for decades. Its design prioritizes operational integrity, a testament to Reliance Electric’s focus on industrial-grade quality.
Application Field
The Reliance Electric 57412 found its primary application in mid-range automation tasks across a diverse set of industries throughout the 1980s and 1990s. It was extensively deployed in material handling systems, controlling conveyor belts, sortation systems, and palletizers within warehouses and distribution centers. In the manufacturing sector, the Reliance Electric 57412 was a workhorse for machine tool control, operating automated assembly lines, injection molding machines, and metal stamping presses. It also served critical functions in packaging machinery, regulating fillers, cappers, labelers, and wrappers. Furthermore, this controller was commonly used in building automation for controlling HVAC systems and in water/wastewater treatment facilities for managing pump stations and filter cycles. These applications leveraged the module’s robust design and reliable logic execution to automate processes that formed the backbone of industrial production.

57412 RELIANCE
Related Products
57411: A related power supply or I/O module within the same AutoMate 15/20 system family.
57413: Often a complementary digital or analog I/O module designed to interface directly with the 57412 processor.
57414: Typically another I/O module variant, such as a specialty communication or high-density I/O card for system expansion.
AutoMate 30/40: The more advanced successor series to the AutoMate 15/20, offering enhanced memory and functionality.
Allen-Bradley SLC 500: A contemporary and later dominant PLC platform from Rockwell Automation that often served as a modernization path for AutoMate systems.
Reliance Electric MAXIS: A variable frequency drive series often controlled or integrated with AutoMate systems for complete motor management.






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