Key Technical Specifications
| Parameter | Details |
|---|---|
| ABB / Foxboro order code | P0973CA |
| Module identifier | FEM100 |
| Product type | Fieldbus expansion module |
| Host system | Foxboro I/A Series / Foxboro Evo with FCP270 |
| Fieldbus channels | 4 × 2 Mbps HDLC module fieldbus |
| Supported devices | 200-series FBMs, FCM2F2/FCM2F4/FCM2F10, FDSI, APACS+/WDPF migration FBMs |
| Redundancy | Dual FEM100 modules provide redundant A/B bus paths |
| Max FBMs per FCP270 | Up to 128 × 200-series FBMs with FEM100 expansion |
| Power supply | Redundant 24 V DC from expansion backplane |
| Mounting | DIN-rail mounted 2-slot or 4-slot expansion backplane |
| Environment | G3-class harsh environment per ISA-71.04 |
| Serviceability | Hot-swappable module replacement |
Product Introduction
Most FCP270 racks don’t die because the processor failed. They die because someone tried to squeeze too many FBMs onto one fieldbus segment and then blamed the controller. The FOXBORO FEM100 P0973CA exists to fix that. It gives an FCP270 four additional 2 Mbps HDLC fieldbus channels, turning a cramped I/O layout into something you can actually commission without fighting bus timeouts.Engineers use it when a single FCP270 needs to talk to more 200-series FBMs than the base configuration allows. With FEM100 expansion, an FCP270 can support up to 128 FBMs instead of the base 32. That is a real capacity jump, not a marketing number. The module sits in a DIN-rail expansion backplane, carries redundant 24 V DC power, and supports A/B bus redundancy. Just don’t assume it works with every Foxboro controller. It is designed for FCP270-based subsystems, and the exact channel count depends on how the expansion backplane is populated.
Quality SOP & Tech Pitfalls
The Lab Report (SOP)
Pre-shipment checks I actually trust:
- Visual/counterfeit inspection: PCB condition, connector pins, label integrity, revision markings, and ESD damage.
- Continuity and insulation check: Backplane pins, fieldbus connectors, and ground paths verified with a Fluke 115.
- Host-platform verification: Confirm FCP270 presence, expansion backplane type, slot assignment, and firmware level.
- Live test when possible: Install into a compatible FCP270 expansion backplane, verify power-up, LED status, and fieldbus recognition.
- Firmware/revision logging: Record P0973CA revision and any firmware-dependent identifiers.
- Anti-static sealing: ESD bag, foam support, and rigid outer box.
If the exact FCP270 test rack is not available, I document what was tested and what must be verified during site commissioning.
The Engineer’s Warning (Pitfalls)
- Wrong host controller kills the swap. FEM100 is an FCP270 fieldbus expander. It is not a generic Foxboro communication card. Dropping it into the wrong backplane wastes time and may damage connectors.
- Redundancy wiring must match. If the system uses dual FEM100 modules for A/B bus redundancy, replacing only one without verifying bus health can leave the system on a single fragile path.
- Field note: A refinery swapped an FEM100 because the FCP270 kept reporting fieldbus faults. The new module powered up fine, but several FBMs stayed offline. The real problem was a damaged bus cable on channel 3, not the module. The plant still had to pull the old FEM100 because the revision did not match, so they ended up fixing both the cable and the board.
Installation & Configuration Guide
- Pre-Installation ⚠️
- Follow site lockout/tagout procedures.
- Confirm whether the FCP270 subsystem is running in redundant or non-redundant mode.
- Photograph the existing FEM100, expansion backplane, slot position, bus cables, and LED status.
- Record FCP270 firmware version, active faults, and FBM assignments per channel.
- Removal
- Label each 2 Mbps fieldbus cable before disconnecting.
- Disconnect redundant 24 V DC power if required by site procedure.
- Release retaining clips and pull the module straight out.
- Place the old module in an ESD bag for revision comparison.
- Installation
- Verify the revision label matches the original. This prevents most startup failures.
- Inspect the expansion backplane connector and bus cable pins.
- Seat the FEM100 firmly into the correct slot.
- Reconnect fieldbus cables exactly as photographed.
- Confirm redundant 24 V DC connections if the backplane supports dual power feeds.
- Power-On & Testing
- Restore power and check front-panel LED status.
- Verify FCP270 recognition of the FEM100 module.
- Confirm each 2 Mbps fieldbus channel reports healthy.
- Check FBM communication status and clear stale faults.
- Run a controlled I/O verification before returning the loop to automatic.
- Save a fresh backup of controller configuration and fault logs.
Compatible Replacement Models
| Replacement option | Compatibility | Notes |
|---|---|---|
| FOXBORO FEM100 P0973CA (same revision) | ✅ Drop-in | Best choice; match revision, backplane slot, and bus cabling |
| FOXBORO FEM100E | ⚠️ Platform-dependent | May be acceptable in newer 200-series backplanes; verify with OEM documentation |
| Other P0973xx variants | ⚠️ Verify with OEM | Different suffixes can change firmware, channel mapping, or host support |
| Non-Foxboro or unverified third-party modules | ❌ Not recommended | HDLC timing, backplane handshake, and FBM mapping may fail |
Frequently Asked Questions (FAQ)
Can I hot-swap the FEM100?
Yes, the FEM100 is designed for hot-swappable replacement in supported Foxboro expansion backplanes. That said, I still prefer a planned window if the system is already showing fieldbus faults. Hot-swapping a failing module in a non-redundant bus can knock out every FBM on that channel.Is P0973CA the same as FEM100?
Yes. FEM100 is the module family name, and P0973CA is the Foxboro order code. Always verify the full revision before purchasing.Will this work with any Foxboro controller?
No. It is intended for FCP270-based I/A Series / Foxboro Evo subsystems. Do not assume compatibility with FCP280, FDC280, or older 100-series architectures without OEM confirmation.How many FBMs can it support?
With FEM100 expansion, an FCP270 can support up to 128 × 200-series FBMs across four fieldbus channels. Without expansion, the base limit is typically 32 FBMs.Do I need two FEM100 modules?
Not always. One module can provide four fieldbus channels. A second FEM100 is used when the system requires redundant A/B bus paths. If redundancy is configured, both modules should match in revision and health.What warranty do you offer?
Standard supply carries a 12-month warranty unless otherwise stated. For critical control loops, keep the old module until the replacement has completed at least one full production cycle.Is this module still available new?
Availability depends on the Foxboro platform and current lifecycle status. Confirm with the OEM datasheet or an authorized Schneider Electric / Foxboro channel before building a long-term spares list.
