The 45C-20A is an upgraded AC-powered CPU module for Reliance AutoMate 20 series PLC systems, which is the A revision of the original 45C20. It integrates processor, power supply and expansion interfaces as an all-in-one controller for small and medium industrial automation. This revision features optimized internal circuits, stronger anti-interference performance and higher operational stability. The product has been discontinued, and only surplus, refurbished or new old stock units are available for maintenance and replacement of legacy equipment.

45C is the unified prefix for all modules of Reliance AutoMate PLC series. 20 represents the standard CPU of AutoMate 20 platform. The hyphen is a common writing form for industrial part numbers, and 45C-20A is fully identical to 45C20A in function. The letter A stands for the first hardware revision with enhanced component reliability.

The module supports switchable 120 VAC and 240 VAC power input with a working frequency of 47 Hz to 63 Hz and typical power consumption of 25 VA. It adopts 4K × 16-bit non-volatile memory that keeps programs and data without battery support. It can manage up to 256 digital I/O points and 64 analog I/O points. It is equipped with 736 internal control coils and 512 data registers, and supports up to 20 PID control loops. The operating temperature ranges from 0°C to 55°C. It can be installed on DIN rails or mounting panels with a rugged metal enclosure, and the total weight is about 1.09 kilograms. A replaceable 2A fuse is built inside for circuit protection.

A terminal block is reserved for AC power connection. A DB25 RS-232 port is used for program uploading, downloading and connection with human-machine terminals, with the default baud rate of 9600 baud. An optional BNC port supports R-NET peer-to-peer network to connect up to 32 PLC nodes. The proprietary backplane interface is used to connect local and remote I/O modules. Multiple LED indicators on the front panel show the working status of power, operation, CPU, communication and faults. This module only matches AutoMate 20 series backplanes and I/O modules.

It executes ladder logic programs to realize automatic control for discrete equipment and process facilities. It provides PID regulation functions to stably control parameters such as temperature, pressure and flow. It realizes data exchange and coordinated control among multiple PLC stations via R-NET network. It completes real-time collection and output of digital and analog signals. The front panel indicators support quick fault checking and daily status monitoring. The upgraded hardware ensures stable operation in complex industrial environments.

It serves as the main controller for legacy AutoMate 20 series PLC systems and acts as a direct replacement for the original 45C20 module. It is widely used in packaging machinery, material handling lines, water treatment and food processing industries. It is suitable for small and medium-sized production equipment that requires analog regulation and multi-station network control. It is also applied to renovation projects of old industrial machines.

Mount the module firmly on DIN rail or panel, and complete power wiring and grounding according to specifications. Check all connecting lines and I/O modules before powering on, and confirm the voltage setting is correct. Conduct quarterly routine inspections to check LED status, cable tightness and module cleanliness, and remove dust regularly to ensure heat dissipation. Cut off the AC power supply completely and wait for full discharge before disassembly and maintenance to prevent electric shock. Use only supporting modules and accessories of AutoMate 20 series to avoid incompatibility and equipment damage.