Description
Foxboro FBM218 | HART Communication Redundant Output Module | 8-Channel Analog Output
Key Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Foxboro / Schneider Electric |
| Model | FBM218 |
| Product Type | HART Communication Redundant Output Interface Module |
| Output Channels | 8 |
| Output Signal | 4–20 mA analog output |
| HART Signal | Digital HART FSK superimposed on analog output |
| Supported HART Versions | 5, 6, 7 |
| Output Isolation | Channel-to-channel and channel-to-logic galvanic isolation |
| Analog Accuracy | ±0.05% of span |
| Resolution | 13-bit |
| Maximum Output Load | 750 Ω |
| Maximum Output Change | 20 mA within 60 ms |
| HART Communication | 1200 baud, asynchronous, half-duplex |
| HART Message Rate | 2 messages/second |
| Maximum HART Field Distance | Up to 3,030 m / 10,000 ft under specified conditions |
| Module Fieldbus | Redundant 2 Mbps HDLC |
| Supply Voltage | 24 VDC +5% / -10% |
| Maximum Consumption | 7 W |
| Maximum Heat Dissipation | 5 W |
| Operating Temperature | -20 to +70°C |
| Dimensions | Approx. 104 × 45 × 114 mm |
| Weight | Approx. 0.284 kg |
| Redundant Arrangement | Master / Tracker pair |
| Typical Termination Assembly | RH926SP |
The Schneider Electric specification states that each FBM218 channel produces a standard 4–20 mA output or a 4–20 mA output with HART FSK superimposed. Each channel has its own isolated power supply and galvanic isolation.
The output circuitry is specified for loads up to 750 Ω, with ±0.05% span accuracy and 13-bit resolution. HART communication uses point-to-point master/slave communication at 1200 baud, with support for HART 5, 6, and 7.
Product Introduction
The Foxboro FBM218 is an 8-channel HART analog output module for Foxboro 200 Series and Foxboro Evo DCS architectures. It sends independent 4–20 mA control signals to field devices while allowing HART digital communication to be superimposed on the same current loop.
The module is specifically designed for redundant output operation. Two FBM218 modules can be installed as a Master/Tracker pair, with the associated redundant adapter and termination assembly allowing the healthy module to maintain the field output if the other module develops a detectable fault.
FBM218
Application Scenarios & Field Pitfalls — Engineer’s Perspective
Engineering Pain Point
An FBM218 problem can affect multiple final control elements simultaneously because one module provides eight analog output channels. When HART diagnostics, output-current faults, or redundancy alarms appear, the engineer should check the FBM, termination assembly, redundant adapter, field loop, and DCS configuration as one signal path.
Typical Applications
- Foxboro Evo / I/A Series process control systems
- 4–20 mA control-valve and actuator outputs
- HART-enabled final control devices
- Redundant analog output applications
- Process plants requiring remote configuration or diagnostics through HART
Technical Pitfalls to Avoid
- Do not confuse with FBM216b.
FBM216b is a redundant HART analog input module, while is a redundant HART analog output module. The two have opposite signal directions and are not substitutes. - Redundancy requires the complete hardware arrangement.
A single provides eight outputs, but module-level redundancy requires a second , adjacent baseplate positions, and the appropriate redundant adapter/termination arrangement. Installing one module does not by itself create redundant output operation. - Check the termination assembly.
Schneider’s documentation identifies RH926SP as the termination assembly for the configuration, with the associated termination cable and certification requirements. Do not assume a termination assembly from another FBM family is interchangeable. - Do not treat HART as a separate Ethernet-style communication port.
The HART signal is superimposed on the 4–20 mA output loop. The module’s DCS-side communication uses the redundant 2 Mbps HDLC fieldbus to the associated FCM or FCP. - Verify fail-safe configuration before replacement.
supports configurable output fail-safe behavior. In a redundant arrangement, the Master and Tracker behavior must agree with the existing Foxboro DCS configuration; a replacement should not be commissioned simply because its hardware number matches.
Related Products
- Foxboro FBM216b — Redundant 8-channel HART analog input module; receives 4–20 mA/HART signals rather than generating outputs.
- Foxboro FBM215 — 8-channel HART analog output module without the same redundant architecture.
- Foxboro FBM214b — 8-channel HART analog input module.
- Foxboro FBM217 — 32-channel discrete input module with redundant-ready architecture.
- Foxboro FBM219 — 24-channel discrete input plus 8-channel discrete output module.
- Foxboro FBM208 — Mixed analog I/O module with 0–20 mA inputs and outputs.
- Foxboro FCM — Fieldbus Communication Module providing the interface between the control system and fieldbus modules.
- Foxboro FCP270 — Field Control Processor used with Foxboro fieldbus I/O architectures.
- Foxboro RH926SP — Termination assembly specified for the 8-channel HART output configuration.
Procurement Check
Before approving an replacement, verify:
- Exact module designation:
- Complete part number, such as P0922VW
- Foxboro system generation
- Standard versus Compact 200 Series hardware
- Hardware revision
- Single or redundant application
- Second in the redundant pair
- Master/Tracker configuration
- Redundant adapter
- RH926SP termination assembly
- Termination cable
- 4–20 mA output assignments
- HART device compatibility
- Existing fail-safe configuration
- 2 Mbps fieldbus architecture
- Baseplate position and connector condition
- Field-loop load, especially where the loop approaches the 750 Ω maximum
Recommended procurement description:
Foxboro HART Communication Redundant Output Interface Module, 8-Channel Isolated 4–20 mA Analog Output, HART 5/6/7 Support, Redundant 2 Mbps HDLC Fieldbus, Foxboro 200 Series / Evo DCS.
The important distinction is simple: is an 8-channel HART analog output module, not an analog input module. For a replacement, match the exact variant, termination assembly, redundancy arrangement, HART requirements, and existing Foxboro DCS configuration rather than matching the FBM number alone.
