Component Snapshot At-a-Glance

• Model: SSA-T8028-0652, Foxboro OEM part marking P0973L
• Alt. P/N: Direct functional replacement: Extreme SSA-T8148; smaller site alternative Foxboro P0973JN
• Product Series: Enterasys S-Series, factory OEM branded for Foxboro I/A Series DCS control system
• Hardware Type: 1U rack mount Layer3 industrial managed aggregation switch
• Key Feature: Pre-configured factory QoS prioritization tuned exclusively for Foxboro Nodebus-over-Ethernet DCS control traffic
• Primary Field Use: Aggregate FCP270/FCP280 controller Ethernet links and build redundant fiber backbone rings across refinery and power plant DCS control cabinets.

SSA-T8028-0652

Hard-Numbers: Technical Specifications

• Protocol Support: Static Routing, OSPF, MSTP, 802.1Q VLAN, ACL, QoS, Modbus TCP pass-through
• Port Count: 48×10/100/1000BASE-T RJ45, 4×SFP+ 10Gbps uplink slots
• Baud/Data Rate: Copper auto-negotiate 10/100/1000Mbps; SFP+ fixed 10Gbps fiber uplink
• Operating Temperature: 0°C ~ +50°C operational; -20°C ~ +70°C storage/transport
• Isolation Rating: 1500VAC surge isolation between copper field ports and internal switch core ASIC
• Power Draw: Max 115W total load, designed for dual redundant AC hot-swap power modules
• Switch Capacity: 176Gbps switching fabric; 131Mpps forwarding rate; 32K MAC address table depth
• Mount Form Factor: Standard 19-inch 1U EIA rack chassis
• Power Module Spec: Compatible with Enterasys SSA-AC-PS hot swap redundant power supplies

The Real-World Problem It Solves

Unmanaged consumer-grade switches drop high-priority DCS interlock packets during broadcast storms, triggering random controller loss and unplanned process trips across refining units. Separate small unmanaged switches scattered per cabinet inflate spare inventory and require extra fiber cabling for site-wide control networking.

Where you’ll typically find it:

• Coal-fired power plant central DCS control room main aggregation cabinet for boiler and turbine FCP controllers
• Refinery CDU/FCC central I/A rack room backbone ring hub connecting multiple process unit control cabinets
• Offshore natural gas production platform DCS control room central SCADA and controller aggregation rack

Factory pre-tuned QoS eliminates unplanned control packet loss and consolidates scattered cabinet-level switching hardware into single rack-mounted aggregation hardware.

Hardware Architecture & Under-the-Hood Logic

This unit uses a dedicated industrial-grade Layer3 ASIC core with split isolated power domains for port group and CPU management sections to block transient cabinet surge damage from crashing full switch operation. It sits as central aggregation layer between field FCP controllers and plant SCADA/OPC server networks on the Purdue automation stack.

1. Copper RJ45 ports receive inbound Ethernet packets from rack-mounted Foxboro FCP controller onboard Ethernet ports.
2. Internal port grouping and preloaded QoS rules tag all DCS control packets for highest forwarding priority ahead of non-critical SCADA background traffic.
3. ASIC routes tagged traffic across defined VLAN boundaries or forwards uplink traffic out assigned SFP+ fiber ports for backbone ring distribution.
4. MSTP protocol continuously monitors fiber ring health and reroutes traffic within milliseconds upon single fiber break in DCS redundant backbone.
5. Outbound processed packets route to plant historian, OPC servers or remote unit controllers based on preconfigured Layer3 routing tables stored in switch onboard flash memory.

SSA-T8028-0652

Field Service Pitfalls: What Rookies Get Wrong

Single power supply deployment in critical DCS control racksNew techs install only one AC power module to cut spare cost; single supply failure takes down entire DCS aggregation switch and drops all connected rack controllers offline.

• Field Rule: Always populate dual redundant SSA-AC-PS power modules for any switch installed on critical process unit DCS control networks.

Using commercial grade non-industrial SFP transceivers in 10G uplink slotsField crew fits low-cost office-rated SFP modules into SFP+ slots; cabinet heat buildup causes intermittent CRC errors and periodic ring split events mid-process run.

• Quick Fix: Replace all non-OEM SFPs with wide-temperature industrial rated transceivers rated 0~70°C operating range per Foxboro DCS spec.

Full factory config reset without backup prior to modificationTechnician wipes entire running-config to troubleshoot port fault; preloaded DCS VLAN/QoS programming erases instantly leading to total PV communication loss sitewide.

• Field Rule: Save full startup-config to external TFTP server before modifying any port or VLAN parameters inside switch CLI.

Commercial Availability & Pricing Note

Please note: The listed price is for reference only and is not binding. Final pricing and terms are subject to negotiation based on current market conditions and availability.