Product Overview

The Foxboro A2H124-24FX P0973BJ is a 24-port managed fiber Ethernet switch specifically configured for the Foxboro I/A Series distributed control system (DCS). Manufactured by Enterasys (SecureStack A2 series) and rebranded under the Foxboro part number P0973BJ, this switch serves as the fiber aggregation layer within legacy I/A Series control networks, connecting field control processors (FCP), fieldbus modules (FBM), and operator workstations over multimode fiber links. The Foxboro A2H124-24FX P0973BJ addresses a fundamental limitation of copper-based industrial Ethernet: the 100-meter distance ceiling and susceptibility to electromagnetic interference from motors, variable frequency drives, and other high-power equipment in process areas.

The Foxboro A2H124-24FX P0973BJ provides 24 fixed 100Base-FX multimode fiber ports using MT-RJ connectors, alongside two SFP gigabit uplink slots and two 10/100/1000 RJ45 ports that can serve as stacking or uplink interfaces. This port configuration allows a single 1U rack-mount unit to replace dozens of individual fiber media converters in a control cabinet, reducing wiring complexity and potential failure points. As the SecureStack A2 platform has reached end-of-life status, the Foxboro A2H124-24FX P0973BJ is primarily sourced as new surplus or tested refurbished stock for maintenance and lifecycle extension of existing I/A Series installations.

 

Technical Specifications

Parameter Name	Parameter Value
Product Model	Foxboro A2H124-24FX P0973BJ
Manufacturer	Enterasys / Foxboro (Schneider Electric)
Product Type	Managed Fiber Ethernet Switch (Layer 2)
Fiber Ports	24 × 100Base-FX, MT-RJ multimode (1300 nm, typical 2 km)
Uplink/Stacking Ports	2 × SFP Mini-GBIC; 2 × 10/100/1000Base-T RJ45
Switching Capacity	12.8 Gbps (standalone); 102.4 Gbps (stacked)
Forwarding Rate	9.5 Mpps (standalone)
MAC Address Table	8,000 entries
VLAN Support	IEEE 802.1Q, up to 4,096 VLAN IDs
Management	CLI, Web GUI, SNMP v1/v2c/v3, Telnet, RMON
Power Input	100–240 VAC, 50/60 Hz (P0973BJ single PSU; P0973BK includes redundant PSU)
Operating Temperature	0°C to +50°C
Form Factor	19-inch 1U rack mount, 441 × 44 × 210 mm

 

Main Features and Advantages

Fiber-first architecture for EMI immunity and distance extension: Every access port on the Foxboro A2H124-24FX P0973BJ is fiber-optic, eliminating the copper cabling that acts as an antenna for electromagnetic noise in industrial environments. This design directly addresses the CRC errors and intermittent controller dropouts that plague copper networks routed near pump motors, MCC cabinets, and variable frequency drives in refinery and chemical plant settings. Multimode fiber extends the reach from the 100-meter copper limit to approximately 2 kilometers, allowing remote I/O cabinets and satellite control rooms to connect directly without intermediate repeaters.

Factory-preloaded DCS QoS for deterministic control traffic: The Foxboro A2H124-24FX P0973BJ ships with quality-of-service rules preconfigured for Foxboro control networks, prioritizing Modbus TCP and proprietary DCS control frames over less time-critical traffic. This out-of-the-box prioritization saves commissioning time that would otherwise be spent tuning queue schedules, and ensures that control-loop data maintains consistent forwarding latency even during periods of heavy network utilization from historian polling or file transfers.

Stacking capability for unified management: Up to eight SecureStack A2 switches, including the Foxboro A2H124-24FX P0973BJ, can be combined into a single logical stack managed via one IP address. In large I/A Series installations spanning multiple control rooms or process units, this stacking architecture simplifies VLAN configuration and firmware updates across the entire switching fabric, reducing the operational burden on maintenance teams managing legacy DCS infrastructure.