Reliance Electric 57413-1A Common Memory Module

Reliance Electric 57413-1A Common Memory Module is a 64K memory upgrade for AutoMax PLC racks, designed to hold configuration data that must be shared among multiple Processor Modules and to arbitrate access to the rack backplane bus so processors can run applications without consuming memory resources. In racks with more than one Processor Module, the Common Memory Module—installed in slot 0—stores I/O definitions and other system configuration, preserving essential settings across processors and enabling consistent behavior across the rack. The module belongs to the 57C413A/57C423 family of common memory modules and is typically paired with a backup battery (sold separately) to retain memory during power loss; installation and operation are described in the J-3636 manual. Physically, the 57413 assembly is a slim memory card consisting of a memory circuit board housed in a protective enclosure with a faceplate, reflecting its role as a compact, field-installable component in legacy AutoMax/DCS-5000 installations. The 57413-1A variant is no longer manufactured, but it remains available on the secondary market for legacy AutoMax and DCS-5000 systems, underscoring its enduring role in multi-processor configurations.