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3. Key Technical Specifications
| Parameter | Value |
|---|---|
| Input Channels | 8 individually isolated |
| Input Signal | 4–20 mA analog or HART FSK superimposed on 4–20 mA |
| HART Protocol Support | Versions 5, 6, or 7 |
| Communication | Point-to-point, master/slave, half-duplex, 1200 baud |
| Message Rate | 2 messages per second |
| Analog Accuracy (incl. nonlinearity) | ±0.075 % of full scale |
| Resolution | 15 bits |
| Update Rate | 100 ms per channel |
| Integration Time | 500 ms |
| Sense Resistor / Input Resistance | 280 Ω nominal (including redundancy adapter) |
| Isolation | Individual channel-to-channel, channel-to-ground, and module logic |
| Compliance Voltage (internal) | 18.5 V DC minimum at 20.5 mA |
| Power Supply | 24 V DC +5 % / –10 % |
| Power Consumption | Approx. 7 W maximum (pair configuration higher) |
| Operating Temperature | –40 to +70 °C (module) |
| Relative Humidity | 5 to 95 % non-condensing |
| Weight | Approx. 284 g (0.32 kg) per module |
| Mounting | Modular baseplate with redundant adapter |
4. Product Introduction
The Foxboro FBM216b is the channel-isolated redundant HART Communication Input Interface Module for the I/A Series and Foxboro Evo DCS. A pair of FBM216b modules operates in Master/Tracker configuration, sharing one common termination assembly through a redundant adapter. Each module provides eight individually isolated 4–20 mA input channels that also support HART Frequency Shift Keying digital communication.
This arrangement delivers high availability for critical analog and HART measurements. Field devices continue to be read by the healthy module if one FBM fails or is removed. The module supports HART universal, common-practice, and device-specific commands (point-to-point only) and is selected when both signal integrity and redundancy are required.
- FBM216B
- FBM216B
5. Troubleshooting Quick Reference
| Symptom | Possible Cause | Relevance to this Part | Quick Check Method | Recommendation |
|---|---|---|---|---|
| Both modules show quality mismatch or failover | Redundant adapter or TA cable problem | ✅ High | Inspect adapter seating and Type-1 cable continuity; compare readings between Master and Tracker | Reseat adapter and cables; verify both modules see identical field signals |
| One module offline / no status | Module failure or Fieldbus path loss | ✅ High | Check module LEDs and redundant Fieldbus status; swap modules if possible | Replace the failed module; confirm configuration matches the pair |
| Analog OK but no HART data | Device address not 0, cable issues, or missing balun | ✅ High | Confirm HART device address and cable quality; review diagnostic buffer for CRC errors | Set devices to point-to-point address 0; add Cable Balun if external power is shared |
| All channels read 0 mA or open | Open field wiring or missing loop power | ✅ Medium | Measure current at TA terminals with multimeter | Verify field transmitter power and wiring before replacing modules |
| Intermittent quality drops | Noise, grounding, or excessive cable length | ✅ Medium | Check shield grounding and port statistics | Improve cable routing and single-point grounding; stay within HART distance limits |
| Module status LED indicates fault | Power or baseplate issue | ❌ Low | Measure 24 V DC at baseplate; check adjacent modules | Resolve power or Fieldbus problem first |
If these checks do not resolve the issue, capture photos of both modules, the redundant adapter, TA terminals, and a system diagnostic log, then contact technical support.
6. Frequently Asked Questions (FAQ)
Q: How does the FBM216b differ from the FBM214b? A: The FBM214b is a single (non-redundant) channel-isolated HART input module. The FBM216b is designed to be used in pairs with a redundant adapter and common termination assembly for Master/Tracker redundancy.
Q: Do I need two FBM216b modules for every installation? A: Yes for full redundancy. A single FBM216b can operate alone, but the intended and supported configuration is a redundant pair sharing one TA via the redundant adapter (typically P0924DT or equivalent).
Q: What termination assembly is required? A: Use the TA specified for FBM216b (examples include P0924JH family). Always match the exact part number to the existing installation and confirm cable type (usually Type 1).
Q: Does it support HART burst mode? A: No. Operation is point-to-point only. Burst mode is not supported.
Q: Can standard 4–20 mA and HART devices be mixed on the same pair? A: Yes. Any mix of conventional 4–20 mA transmitters and HART devices is supported across the eight channels.
Q: Is this module compatible with current Foxboro Evo systems? A: Yes. It is supported on appropriate I/A Series software revisions and Foxboro Evo Control Core Services v9.0 and later. Confirm the exact system software version before installation.
Q: Why are surplus units priced lower than factory-new listings? A: Most available stock is New Surplus—never installed, from excess project inventory. Units are inspected for physical condition. A 1-year warranty is provided; the original OEM warranty does not transfer with surplus material.
