Key Technical Specifications
| Parameter | Specification |
|---|---|
| Part Number | P0926TL |
| Module Type | FBM222 — PROFIBUS-DP/PA Interface |
| System | FOXBORO I/A Series DCS |
| PROFIBUS Ports | 2 electrically isolated channels |
| Protocol Support | PROFIBUS-DP/PA, Class 1 Master, multi-master capable |
| Slaves per Port | Up to 125 |
| Max Frame Data | 244 bytes per frame |
| Redundancy | Hot-swappable redundant pair (with P0922RK adapter) |
| Compatible TA | P0926TH (FBM222 termination assembly) |
| Power | 24 VDC, dual redundant input, ≤4 W |
| Operating Temp | -20°C to +60°C |
| Mounting | I/A Series FBM rack, IP20 indoor |
Product Introduction
If your I/A Series rack still talks to drives, valve positioners, or skid-mounted instruments over PROFIBUS, the FBM222 is usually the only card in the chassis doing that job. P0926TL is the FBM222 variant — two isolated PROFIBUS ports, Class 1 master, sitting in the standard FBM slot. It is not a generic serial card. It is not a Modbus gateway. It is the PROFIBUS mouthpiece for the controller.Engineers keep this module in the spare cabinet because losing it means an entire segment of field devices goes silent. The redundancy option matters here. With a P0922RK adapter, you can run a primary/standby pair so a single module failure does not take down the whole bus. I have seen plants run these for years without issues, provided the termination, shielding, and TA cabling were done correctly. Sloppy PROFIBUS wiring will make even a perfect FBM222 look bad.
Quality SOP & Tech Pitfalls
The Lab Report (SOP)
Visual inspection first — label, revision, pin condition, no burnt smell. Then it goes into a live I/A Series test rack. We verify 24 VDC draw, LED status, and that the module enumerates in the system. Next, a PROFIBUS segment simulator or known slave checks bus activity and master response. We log the firmware/revision, photograph the label, and seal it in an anti-static bag. A Fluke 115 checks the power input rails before anything leaves the bench.The Engineer’s Warning (Pitfalls)
Two mistakes kill uptime with this module. First, swapping P0926TL for P0917HD (FBM223) without verifying the configuration. They are both PROFIBUS FBMs, but they are not identical twins. The system cares. Second, replacing a redundant pair and forgetting the P0922RK adapter or the primary/standby assignment. I once watched a technician plug a fresh FBM222 into a redundant slot, see the green LED, and declare victory — while the controller still flagged the bus as degraded because the redundancy adapter was missing. The bus stayed up, but the alarm never cleared until the adapter was seated.
Installation & Configuration Guide
- Pre-Installation ⚠️
Confirm the I/A Series release supports FBM222/P0926TL. Photograph the existing module label, slot position, redundancy adapter, and TA wiring. Schedule the swap during a maintenance window if the module is not already redundant. - Removal
Tag all cables. Release the TA connector carefully — do not yank the PROFIBUS cable by the jacket. Unlatch the module and slide it out. If redundant, remove only the failed unit first. - Installation
Copy the slot number, redundancy role, and TA wiring exactly. Seat the P0922RK adapter if this is a redundant application. Insert the P0926TL firmly until the latch engages. Reconnect the TA and PROFIBUS cables. - Power-On & Testing
Verify 24 VDC at the rack. Watch the LED sequence. Check the I/A Series configuration tool for module status, bus health, and slave enumeration. Confirm that all PROFIBUS devices return valid data and that no redundancy alarms persist.
Compatible Replacement Models
| Compatibility | Model | Notes |
|---|---|---|
| ✅ Drop-in Replacement | FBM222 P0926TL | Same module, same revision family. Verify label and firmware. |
| ⚠️ Software/Config Check | FBM222 P0917HD | Also an FBM222 PROFIBUS module, but may require configuration verification before substitution. |
| ⚠️ Redundancy Accessory | P0922RK | Redundancy adapter for FBM222/FBM228 — not a module replacement, but required for hot-standby pairs. |
| ❌ Not Interchangeable | FBM223 P0917HD / P0917SY | Different FBM type; do not substitute without OEM confirmation. |
| ❌ Not Interchangeable | FBM224 P0926GG | Modbus module, different protocol and configuration. |
Frequently Asked Questions (FAQ)
Can I hot-swap a P0926TL while the rack is running?
Yes, the FBM222 is hot-swappable in an I/A Series rack. But “can” and “should” are different questions. If it is the only module on that PROFIBUS segment, you will lose those devices during the swap. Redundant pairs make this far less painful.Is P0926TL the same as P0917HD?
Both are listed as FBM222 PROFIBUS modules in many spare parts catalogs, but they are not automatically interchangeable in the field. Check the I/A Series configuration, firmware, and OEM documentation before swapping.Does it need a termination assembly?
Yes. The FBM222 uses a TA such as P0926TH. The PROFIBUS cables land on the TA, not directly on the module in most installations. Missing or loose TA wiring is a common cause of intermittent bus faults.What happens if redundancy fails?
The remaining module usually keeps the bus alive, but you lose the safety net. Treat a degraded redundant FBM222 as a priority-one spare replacement, not a “fix it next turnaround” item.Is this module obsolete?
FOXBORO I/A Series 200-series FBMs are mature products. Availability depends on stock and revision. Always confirm the exact P0926TL label and condition before purchasing.Can it replace an FBM223 or FBM224?
No. FBM223 and FBM224 serve different communication roles. Dropping the wrong FBM into the slot will not bring the bus back — it will just give you a new alarm.
