Product Overview

The Yokogawa ALF111-S51 acts as a high-performance digital gateway, enabling the CENTUM VP and ProSafe-RS control systems to interface directly with FOUNDATION Fieldbus (FF) H1 segments. This module serves as a Link Active Scheduler (LAS), managing the precise cyclic and acyclic data exchange required for multi-variable field instruments. By utilizing the ALF111-S51, industrial facilities can transition from traditional analog loops to a fully digital architecture, gaining access to extensive device diagnostics, reduced wiring complexity, and enhanced signal integrity. This specific S51 configuration includes the ISA Standard G3 conformal coating, providing essential defense against atmospheric corrosion in challenging chemical or coastal environments.

Technical Infrastructure and Hardware Profile

The ALF111-S51 is designed for high-density integration within Yokogawa node units, offering reliable digital bus management.

• Communication Standard: FOUNDATION Fieldbus H1 (31.25 kbps)

• Number of Ports: 4 segments per module

• Maximum Devices: Up to 32 devices per module (8 per segment)

• Digital Interface functionality: Link Active Scheduler (LAS) and Basic Device roles

• Corrosion Resistance: ISA Standard G3 compliant coating

• Terminal Interface: Includes ATF9S-00 pressure clamp terminal block

• Current Consumption: 0.5 A at 5 V DC

• Module Weight: 0.4 kg (400g)

• Full Shipping Weight: 2.0 kg

• Unit Dimensions: 130 mm x 130 mm x 42 mm

• Environmental Tolerance: 0 to 60 degrees Celsius operating range

Strategic Industrial Applications

The ALF111-S51 is a foundational component for plants seeking data-rich instrumentation and decentralized control.

• Advanced Process Monitoring: Connecting smart transmitters (pressure, temperature, flow) to the DCS while capturing secondary variables and device health status simultaneously.

• Corrosive Gas Protection: Operating in refineries or wastewater treatment plants where the G3 coating prevents circuit failure caused by hydrogen sulfide or other industrial pollutants.

• Redundant Digital Backbones: Implementing dual-module configurations to ensure that communication with field segments remains active even during a module maintenance event.

• Interoperability Management: Bridging diverse third-party field instruments into a unified Yokogawa control environment through the vendor-neutral FOUNDATION Fieldbus protocol.

FAQ

Q: What is the significance of the /F9S00 suffix on this module?

A: The /F9S00 suffix indicates that the module is supplied with the ATF9S-00 pressure clamp terminal block. This ensures secure and efficient wiring for the four Fieldbus H1 segments directly at the module interface.

Q: How many Fieldbus devices can I connect to a single ALF111-S51?

A: While the technical maximum is 32 devices per module (8 per segment), actual counts may vary based on power supply capacity and the communication traffic requirements of your specific control loops.

Q: Does this module support Link Active Scheduler (LAS) functions?

A: Yes, the ALF111-S51 can function as the LAS for each of its four segments, managing the bus communication schedule and ensuring deterministic data updates.

Q: Is it necessary to use a Fieldbus Power Supply with this module?

A: Yes, the ALF111-S51 provides the communication interface, but an external Fieldbus Power Supply and Power Conditioner are required to provide the necessary DC voltage to the field instruments.

Q: Can the ALF111-S51 be hot-swapped in a running system?

A: In a dual-redundant configuration, the module can be replaced while the system is under power without losing communication with the field instruments, provided the redundant partner module is healthy.