Yokogawa ALF111-S00 FOUNDATION Fieldbus Communication

The Yokogawa ALF111-S00, also cataloged as the ALF111 FOUNDATION Fieldbus Communication Module, operates as a dedicated hardware component for Link Active Scheduler (LAS) management and H1 fieldbus segment distribution within distributed control system (DCS) platforms.

Suffix Breakdown & Model Matrix

The ALF111 series utilizes explicit engineering suffixes to define hardware builds and hardware style revisions. Below is the technical breakdown for the ALF111-S00 configuration:

• ALF111: Core base model designator for the FOUNDATION Fieldbus H1 communication module.
• -S: Standard type construction baseline for standard industrial enclosure installation.
• 0: Phase indicator slot mapping designator.
• 0: Basic functionality block revision baseline.

Hardware Specifications

Process Control System Specifications

• FOUNDATION Fieldbus / Profibus PA Connectivity Operating as a Link Active Scheduler (LAS) master node and designated Clock Master, the module maintains strict deterministic control over the 31.25 Kbps H1 segment loop. It governs macrocycle execution timings, synchronizes clock signals across downstream field nodes, and transfers periodic process variables directly into the central DCS database for regulatory control loop execution.
• Deterministic Processor Offloading and Redundancy Pairing The module manages synchronous scheduled communications and asynchronous messaging internally, ensuring network traffic routines do not introduce execution jitter to the main Field Control Station (FCS). Dual-redundant pairing options support installing two ALF111 units in the same node slot layer to manage automatic bump-less transfer of the LAS roll during an active hardware fault.

Frequently Asked Questions

Q: What are the consequences if a module running as the active Link Active Scheduler (LAS) fails on the H1 loop?

A: If the primary ALF111-S00 fails in a non-redundant layout, a configured backup LAS device located directly on the field network segment detects the loss of the scheduling token and automatically assumes control of the macrocycle execution timing to prevent loss of process data.

Q: Can the ALF111-S00 directly power the 32 fieldbus transmitters connected to its H1 segment loop?

A: No. The communication module does not inject operating power into the signal lines. An external, dedicated fieldbus power supply paired with an impedance-matching fieldbus power conditioner must be installed on the H1 network segment to drive connected transmitters and valves.