Product Core Brief
- Model: EC401-50, Style S3
- Brand: YOKOGAWA
- Series: CENTUM CS 3000 / Field Control Unit (FCU)
- Core Function: Single-port ESB bus coupler that connects the FCU processor to remote I/O nodes over the ESB bus.
- Product Type: ESB Bus Coupler Module
- Key Specs: 1-port ESB bus | Standard type, no explosion protection | Style S3, compatible with CP471-01 | Redundant pair supported
- Condition: New Surplus / OEM Original
Key Technical Specifications
- Part Number:
- Style Code: S3
- Product Type: ESB Bus Coupler Module for CENTUM CS 3000 FCU
- System Compatibility: CENTUM CS 3000 Field Control Unit
- Bus Interface: ESB bus
- Port Configuration: Single-port ESB bus coupler
- Suffix Code: “-5” = standard type without explosion protection; “0” = basic version
- Redundancy: Dual-redundant configuration supported by installing two EC401-50 modules
- CP471-01 Compatibility: Requires EC401 style S3 or later
- Mounting: FCU backplane slot
- Explosion Protection: None (standard industrial type)
Product Introduction
This EC401-50 is the style S3 version of the single-port ESB bus coupler used in YOKOGAWA CENTUM CS 3000 field control units. It bridges the FCU processor and the ESB bus, enabling communication with remote I/O nodes and keeping control execution synchronized with field data exchange.
The S3 style code matters. If the station runs a CP471-01 processor, the EC401 must be style S3 or later; older styles are not supported for that pairing. Two EC401-50 modules can be installed as a redundant pair, so one coupler failure does not necessarily knock out ESB communication.
QA & Testing SOP
- Label and style-code verification: Confirm “EC401-50” and style code S3 on the module label; mismatched styles are the most common procurement error.
- Connector and PCB inspection: Check backplane pins, housing, and PCB for bent pins, corrosion, or contamination.
- Cold-boot test: Install into a verified FCU rack, apply power, and confirm module initialization and status indicators.
- ESB communication check: Confirm the processor recognizes the coupler and that remote I/O nodes are reachable.
- Redundancy verification: For dual EC401-50 installations, confirm primary/standby status and failover behavior.
All units are handled with ESD-safe packaging and labeled with received condition, inspection date, and test status.
Installation Pitfalls & Guide
- ❗ Verify style S3 before installation. CP471-01 requires EC401 style S3 or later; an earlier style will not satisfy that requirement.
- ❗ Do not mix styles in a redundant pair. Redundant EC401-50 modules should be matched to avoid unpredictable failover.
- ❗ Protect the backplane connector. Bent pins or dirty contacts are a frequent cause of communication faults after replacement.
- ❗ Check ESB cabling and termination. Loose or misrouted ESB cables can cause intermittent node dropouts even when the coupler itself is healthy.
Replacement steps:
- Confirm FCU type, processor model, and EC401 style code.
- Remove the failed coupler following ESD procedures.
- Seat the new EC401-50 S3 firmly and verify connector alignment.
- Power on, confirm ESB communication, and test redundancy if applicable.
Technical FAQ
What does “S3” mean on EC401-50 S3?
It is the style code. For CP471-01 processors, the EC401 must be style S3 or later.
Case S3 with ?
Yes. EC401-50 S3 meets the “style S3 or later” requirement for CP471-01.
Can I run two EC401-50 modules in redundancy?
Yes. Two EC401-50 modules can be installed as a redundant pair for ESB bus communication.
What does the “-50” suffix mean?
“-5” indicates a standard type without explosion protection, and “0” indicates the basic version.
Do you test these before shipping?
Surplus stock is visually inspected, connector-checked, and power/communication-tested where a suitable CENTUM CS 3000 test rack is available. Any limitations are disclosed per lot.
