Description
Foxboro FBM230 P0926GU | 4-Port Serial FDSI Module
Product Introduction
The Foxboro FBM230 P0926GU is a communications module, not a conventional process I/O card. Its job is to bring data from serial field devices into the Foxboro control database through four independently configurable serial ports.
Each port can be configured for RS-232, RS-422, or RS-485, allowing different serial-device architectures to coexist on the same FBM230. The module uses downloadable I/O software drivers to handle field-device protocols and convert the resulting information into standard Distributed Control Interface (DCI) data. Schneider’s current specification identifies P0926GU specifically as the FBM230 module.
This distinction matters when sourcing surplus hardware. A listing for “FBM230 P0926GU” should refer to the electronics module itself. P0926PA is the ring-lug termination assembly, while RH926GH is the current compression-screw termination assembly.
FBM230 P0926GU
Key Technical Specifications
- Model: FBM230
- Module Part Number: P0926GU
- Function: Field Device System Integrator
- Configuration: Single / non-redundant FDSI module
- Serial Ports: 4
- Port Configuration: Independently configurable
- Electrical Interfaces: RS-232, RS-422, RS-485
- RS-485 Capacity: Up to 64 devices total
- RS-485 Port Capacity: Up to 16 devices per port
- RS-232/RS-422 Capacity: Up to 4 directly connected devices
- Maximum DCI Connections: 2,000
- Serial Baud Rates: 300 to 115,200 baud
- Character Format: 8-bit
- Parity: Odd, even, or none
- Stop Bits: 1 or 2
- Module Fieldbus: Redundant 2Mbps
- Supply Voltage: 24VDC, +5% / -10%
- Maximum Power Consumption: 7W
- Maximum Heat Dissipation: 7W
- Operating Temperature: -20°C to +70°C
- Storage Temperature: -40°C to +70°C
- Relative Humidity: 5–95%, noncondensing
- Environmental Class: ISA S71.04 Class G3
- Module Mass: Approximately 284g
- Dimensions: 102 × 45 × 104mm
- Height Including Mounting Lugs: 114mm
Schneider specifies RS-422/RS-485 communication distances up to 1,200m (3,937ft) under the applicable conditions, while RS-232 is limited to up to 15m (50ft) for custom cables meeting the stated EIA requirements.
Four-Port Serial Architecture
The four serial ports are the defining feature of the .
A typical architecture might use:
- RS-232 for a single point-to-point instrument
- RS-422 for a dedicated multidrop-capable device arrangement
- RS-485 for multiple field devices on a shared bus
The port configuration is independent, so the is not restricted to one serial standard across all four ports.
For RS-485, the documented capacity is up to 16 devices per port, or 64 devices across four ports. Direct RS-232/RS-422 connections support up to four devices.
Supported serial speeds include:
- 300 baud
- 600 baud
- 1,200 baud
- 2,400 baud
- 4,800 baud
- 9,600 baud
- 19,200 baud
- 38,400 baud
- 57,600 baud
- 115,200 baud
Correct baud rate, parity, stop bits, device address, and protocol-driver configuration are all necessary for reliable communication.
Protocol and DCI Integration
The does not function merely as a passive RS-485 converter.
It uses downloadable software drivers to communicate with supported field-device protocols. The driver interprets the serial data and maps useful information into the Foxboro DCS database through DCI blocks.
The specification supports data representations including:
- Binary values
- Integer values
- Floating-point values
- Packed digital values
- Pulse-related data
- String data
- Redundant input data structures
The maximum documented capacity is 2,000 DCI connections. The actual number of useful process points depends on the selected driver, field-device protocol, polling requirements, and data structure.
Do not assume that every Modbus or serial device can simply be connected and recognized. Physical-layer compatibility and application-layer protocol compatibility are separate engineering problems.
Module Fieldbus
The connects to the Foxboro control system through the redundant 2Mbps Module Fieldbus.
The module can communicate through either Fieldbus path, providing communication-path redundancy at the control-system interface.
Compatible Foxboro equipment documented for this family includes:
- FCM100E
- FCM100Et
- FCP270
- FCP280
This should not be confused with serial-port redundancy. The four field-device ports remain part of the FDSI architecture; the redundant 2Mbps Fieldbus concerns communication between the FBM and the Foxboro control system.
Termination Assembly Compatibility
The correct procurement configuration is:
P0926GU + Type 5 termination cable + appropriate TA
Associated termination assemblies include:
- P0926PA — ring-lug termination assembly
- RH926GH — compression-screw termination assembly
- P0926GH — earlier compression-screw identifier superseded by RH926GH
Schneider’s current documentation explicitly identifies RH926GH as superseding P0926GH.
The termination assembly provides the physical field connections for the four serial ports and includes the relevant RS-232 signal routing and RS-422/RS-485 termination provisions.
The -to-TA cable is Type 5 and can be supplied in lengths from 1m to 5m.
Global Sourcing & Live-Test SOP
For a used or surplus , power-up alone is not an adequate functional test.
1. Inbound Verification
- Photograph the complete label.
- Record the serial number.
- Verify the module is actually marked .
- Inspect the Fieldbus connector.
- Inspect the four serial interfaces.
- Check for bent contacts, corrosion, contamination, or enclosure damage.
- Confirm whether the TA and Type 5 cable are included.
- Record firmware and hardware identification where accessible.
2. Live Simulation
Use a suitable Foxboro test rack or controlled serial test environment.
Verify:
- 24VDC power-up
- Module Fieldbus communication
- Module diagnostics
- Port configuration
- RS-232 communication
- RS-422 communication
- RS-485 communication
- Baud-rate changes
- Parity settings
- Stop-bit settings
- Device addressing
- Driver operation
- DCI data exchange
For RS-485 testing, use a known-good test device or serial analyzer rather than relying only on module LEDs.
