Reliance Electric AutoMax Modules 57C404B Network Communications Module

Technical Dossier

Product Details And Specifications

Reliance Electric AutoMax Series Technical Notes

The Evolution of AutoMax Architecture

AutoMax was architected around a proprietary high-speed serial network — the AutoMax Network — capable of coordinating multiple controller nodes, I/O racks, and drive interfaces across a plant floor. Early-generation systems (circa 1985–1992) used the 57C400-series network interface cards operating at 57.6 kbps, providing deterministic scan-cycle communication between the master controller and remote I/O drops. The mid-generation transition (1992–1998) introduced enhanced network modules such as the 57C404B and 57C405, which supported higher node counts and improved diagnostic capabilities. Late-generation AutoMax hardware (1998–2005) added Ethernet gateway modules and DeviceNet adapters, enabling integration with supervisory SCADA systems without replacing the core AutoMax backplane infrastructure. Reliance Electric was acquired by Rockwell Automation in 1994; subsequent product support transitioned to Rockwell's Allen-Bradley service infrastructure. The AutoMax line reached end-of-manufacture status progressively between 2002 and 2008, with official Rockwell support sunset occurring around 2012. As of 2026, the platform is firmly in the obsolete/legacy category, yet remains operational in numerous facilities where capital replacement projects have been deferred. Compatibility between early and late-generation modules requires careful attention to firmware revision levels and backplane slot addressing — cross-generation substitution without engineering review is not recommended.

AutoMax Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced components within the Reliance Electric AutoMax platform. Each entry reflects a distinct hardware function within the system architecture.

Controllers / CPUs

• 57C321: AutoMax CPU Module — primary programmable controller, ladder/function block execution
• 57C322: AutoMax Enhanced CPU — extended memory, faster scan cycle vs. 57C321
• 57C323: AutoMax CPU with expanded I/O map support for large-node configurations
• 57C324: AutoMax High-Performance CPU — dual-port RAM, deterministic real-time kernel

Network Communications Modules

• 57C404B: AutoMax Network Communications Module — token-ring network interface, multi-node coordination
• 57C405: AutoMax Enhanced Network Module — increased node count, improved diagnostics
• 57C406: AutoMax Ethernet Gateway Module — bridges AutoMax network to Ethernet/IP supervisory layer
• 57C410: AutoMax DeviceNet Scanner — integrates DeviceNet field devices into AutoMax I/O scan

Analog I/O Modules

• 57C430: 8-channel Analog Input Module — 4–20 mA / 0–10 V, 12-bit resolution
• 57C431: 8-channel Analog Output Module — 4–20 mA, isolated outputs
• 57C432: 16-channel Analog Input Module — high-density process variable acquisition

Digital I/O Modules

• 57C450: 32-channel Digital Input Module — 24 VDC, optically isolated
• 57C451: 32-channel Digital Output Module — 24 VDC sourcing, short-circuit protected
• 57C452: 16-channel Digital Input / 16-channel Digital Output Combo Module

Power Supply Modules

• 57C300: AutoMax Rack Power Supply — 5 VDC / 24 VDC backplane power, single-slot
• 57C301: AutoMax Redundant Power Supply Module — hot-swap capable, for high-availability racks