Omron 57C-404B Communication Module for 57C Series
In modern industrial automation, no component operates in isolation. The Omron 57C-404B (also referenced as 57C-424) is a dedicated serial communication module engineered to serve as a critical communication bridge within the 57C Series programmable controller architecture. Rather than functioning as a standalone peripheral, the 57C-404B is designed from the ground up to integrate seamlessly across the control layer, I/O layer, network layer, power layer, HMI layer, and execution layer — delivering the signal integrity, protocol flexibility, and long-term reliability that demanding industrial environments require.
Understanding the 57C-404B means understanding the system it inhabits. The Omron 57C Series platform is a rack-based modular PLC architecture built for process-intensive applications where communication stability, deterministic scan cycles, and modular expandability are non-negotiable. The 57C-404B occupies the communication slot within this architecture, enabling the CPU to exchange data with external devices, field instruments, drives, and supervisory systems through standardized serial protocols. Its role is not peripheral — it is structural.
Product Specification Table
| Parameter |
Specification |
| System Role |
Serial Communication Module — 57C Series Rack Architecture |
| Compatible Platform |
Omron 57C Series PLC (57C-404B / 57C-424) |
| Communication Protocols |
RS-232C, RS-422/485, Host Link (SYSMAC WAY), Toolbus |
| Number of Ports |
Up to 2 serial ports (port configuration model-dependent) |
| Baud Rate |
1,200 to 19,200 bps |
| Data Format |
7/8 data bits, even/odd/no parity, 1/2 stop bits |
| Electrical Interface |
RS-232C (±15V), RS-422/485 (differential, multi-drop capable) |
| Power Consumption |
Supplied via 57C Series backplane bus |
| Installation Environment |
0–55°C operating, 10–90% RH non-condensing, DIN rail / rack mount |
| Communication Mode |
Full-duplex (RS-232C), Half/Full-duplex (RS-422/485) |
| Country of Origin |
Japan |
| Warranty |
warranty terms confirmed during quotation — Tested, inspected, and shipment arranged after confirmation |
System Compatibility Notes
The 57C-404B achieves its full value only when viewed within the broader 57C Series control system architecture. At the control layer, the Omron 57C-CPU1 or 57C-CPU3 central processing unit governs the scan cycle and ladder logic execution. The 57C-404B plugs directly into the 57C Series backplane rack — such as the Omron 57C-BP08 8-slot backplane — and communicates with the CPU through the internal bus, ensuring zero-latency data exchange between the communication module and the program execution environment.
Power integrity is maintained by the Omron 57C-PS13 or equivalent power supply module, which provides regulated DC voltage to all rack-mounted modules including the 57C-404B. Stable power delivery is essential for maintaining serial communication signal quality, particularly in RS-485 multi-drop networks where voltage fluctuations can introduce framing errors or data corruption across long cable runs.
At the I/O layer, digital input modules such as the Omron 57C-ID212 and digital output modules like the Omron 57C-OD212 collect field signals from sensors, limit switches, and actuators. The 57C-404B enables the CPU to relay processed I/O data upstream to SCADA systems or downstream to intelligent field devices — such as variable frequency drives, smart transmitters, or remote I/O adapters — using Host Link or RS-485 Modbus-compatible framing.
For human-machine interface integration, the 57C-404B’s RS-232C port can be connected to Omron NT-series or NS-series HMI panels, enabling real-time process visualization and operator input without requiring a dedicated Ethernet network. This is particularly valuable in retrofit projects where legacy HMI infrastructure must be preserved while modernizing the control platform.
In redundant or distributed architectures, the 57C-404B can serve as a gateway between the primary PLC rack and secondary communication networks, supporting system integration across multi-vendor environments. When paired with an Omron 57C-LK201 or equivalent link adapter, the system can extend communication reach across plant-wide RS-485 networks spanning hundreds of meters — maintaining data coherence across all nodes in the control hierarchy.
Industrial Application Notes
The Omron 57C-404B is deployed across a wide range of industrial sectors where serial communication reliability and system architecture consistency are paramount.
In power generation and distribution facilities, the 57C-404B enables PLC-to-relay communication for protection coordination, load shedding logic, and substation automation — where deterministic serial communication is preferred over Ethernet for its simplicity and noise immunity in high-voltage environments.
In petrochemical and refinery process control, the module bridges the 57C Series PLC to field-mounted analyzers, flow computers, and pressure transmitters via RS-485 multi-drop networks. Its ability to handle multiple baud rates and parity configurations makes it adaptable to the diverse instrument ecosystems found in process plants.
In water and wastewater treatment systems, the 57C-404B supports communication between the PLC and remote pump stations, chemical dosing controllers, and SCADA RTUs — enabling centralized monitoring of distributed infrastructure with minimal wiring overhead.
In mining and metallurgical operations, where environmental conditions are harsh and communication distances are long, the RS-422/485 interface of the 57C-404B provides differential signaling that resists electromagnetic interference from heavy machinery, conveyor drives, and smelting equipment.
In packaging and discrete manufacturing lines, the module facilitates high-speed data exchange between the 57C Series PLC and barcode readers, vision systems, and servo drive controllers — supporting traceability, reject handling, and production reporting functions that require reliable, low-latency serial communication.
Product Compatibility FAQ
Q1: Is the Omron 57C-404B compatible with both RS-232C and RS-485 networks in the same installation?
Yes. The 57C-404B supports multiple serial interface standards, and depending on the port configuration, it can simultaneously serve an RS-232C connection (e.g., to a local HMI or programming terminal) and an RS-485 multi-drop network (e.g., to field instruments or remote I/O). This dual-interface capability makes it well-suited for layered automation architectures where different communication tiers use different physical standards. Confirm the specific port assignments with the 57C-404B hardware manual before wiring.
Q2: How does the 57C-404B integrate into an existing 57C Series rack without disrupting the running system?
The 57C-404B is a rack-mounted module that installs into any available communication slot on the 57C Series backplane. In most configurations, module installation requires the rack to be powered down briefly for safe insertion. After installation, the CPU must be configured via the programming tool to recognize the new communication module and assign the appropriate port parameters (baud rate, protocol, station number). No physical modifications to the backplane or CPU are required, making integration straightforward for qualified engineers familiar with the 57C Series platform.
Q3: What does the warranty terms confirmed during quotation cover, and what support is available for long-term maintenance?
Every Omron 57C-404B unit supplied by ZYPLC is covered by a warranty terms confirmed during quotation against manufacturing defects and functional failures under normal operating conditions. Prior to shipment, each unit undergoes functional testing to verify communication port integrity, backplane bus compatibility, and protocol response. For long-term maintenance planning, ZYPLC supports RFQ sourcing for 57C Series modules to support ongoing spare parts programs — reducing the risk of extended downtime due to obsolete component unavailability. Technical support for installation, configuration, and troubleshooting is available through our sales and engineering team.
