Description
Product Introduction & Engineering Value
I’ve installed these whenever a plant needed clean, isolated discrete outputs without drawing the load current through the module power supply. The FBM242 provides sixteen independently isolated discrete output channels. An external power source (up to 60 V DC) is switched by the module to energize field devices. Associated Termination Assemblies allow direct solid-state switching or relay outputs for 120 V AC/125 V DC and 240 V AC loads.
The module executes the Discrete Output or Ladder Logic application program and supports a configurable Fail-Safe option. It mounts on a standard 200 Series baseplate and communicates with the FCP over the 2 Mbps Module Fieldbus. The design is suitable for Class G3 harsh environments.
Technical Specifications
| Parameter | Value |
|---|---|
| Output Channels | 16, channel-isolated |
| Applied Voltage (solid-state) | 15 to 60 V DC maximum |
| Load Current | 2.25 A maximum per channel |
| In-Rush Current | 8 A (20 ms) at 30 °C; 6.4 A (20 ms) at 70 °C |
| On-State Voltage Drop | 0.2 V maximum at 2.25 A |
| Off-State Leakage | 0.1 mA maximum |
| TA Options | Solid-state 60 V DC, or relay outputs for 120 V AC/125 V DC / 240 V AC |
| Application Programs | Discrete Output or Ladder Logic |
| Fail-Safe | Configurable |
| Power Supply (module) | 24 V DC +5% / –10% (redundant) |
| Power Consumption | 3 W maximum |
| Operating Temperature | –20 to +70 °C (–4 to +158 °F) |
Field Application & The “Trench” Experience
A Midwest chemical plant needed sixteen high-current discrete outputs to drive solenoid valves and motor starter interlocks on a batch reactor train. The existing cards were limited in current and isolation. An FBM242 was installed with a relay-style Termination Assembly. External 24 V DC and 120 V AC supplies were landed on the TA. After loading the Discrete Output application program and setting the fail-safe states, all sixteen points operated cleanly with full channel isolation and no shared load current through the module power supply.
Typical niche applications:
- High-current discrete switching of solenoid valves and interlocks on a multi-reactor batch system
- Isolated outputs to motor starter coils and contactor circuits in a large MCC lineup
- Relay-isolated 120 V AC or 240 V AC switching for legacy equipment that cannot accept low-voltage solid-state outputs
FBM242
FBM242
Transparency SOP: QA & Testing
- Visual inspection of housing, connectors, and labeling
- Power-up on dual 24 V supplies with Module Fieldbus communication verification
- Channel-by-channel switching test under rated load current
- Isolation resistance check between channels and from channels to logic ground
- Fail-safe configuration verification
- Extended burn-in while cycling outputs and monitoring for any leakage or voltage-drop increase
The Veteran’s Tech Trap Guide
⚠️ External power is required. The FBM242 does not supply the field load current. An external source must be provided and correctly wired through the Termination Assembly. Missing or incorrect external power is the most common reason outputs appear dead after installation.
PRO TIP: Confirm the Termination Assembly type before ordering. Solid-state TAs are limited to 60 V DC; relay TAs are required for 120 V AC or 240 V AC loads. Using the wrong TA will either limit voltage capability or leave the outputs non-functional.
⚠️ Watch in-rush current. Although continuous load is rated at 2.25 A, the in-rush limit is time- and temperature-dependent. High-inrush devices (large contactors or solenoids) can exceed the short-term rating and damage the output stage if not properly managed.
Dynamic FAQ
Q: Does the FBM242 supply power to the field devices? A: No. It switches an externally supplied voltage (up to 60 V DC solid-state, or higher voltages via relay TAs) to the field loads.
Q: What load current can each channel handle? A: 2.25 A continuous maximum per channel, with higher short-duration in-rush capability.
Q: Can the module drive 120 V AC or 240 V AC loads? A: Yes, when used with the appropriate relay-style Termination Assembly.
Q: Is a Fail-Safe configuration available? A: Yes. The Discrete Output application program supports configurable fail-safe behavior for the outputs.
Q: Are New Surplus FBM242 units original Foxboro product? A: Yes. Units are original OEM material that have passed full switching, isolation, and functional testing.
Q: What warranty is provided? A: 12-month warranty against defects in materials and workmanship from the date of shipment for both New Surplus and fully tested refurbished units.
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