KFD2-STC4-EX1.2O Signal Splitter with HART Pass-Through – Installation & Setup Guide
Product Introduction
The KFD2-STC4-EX1.2O belongs to Pepperl+Fuchs' established K-System family of intrinsic safety barriers. This module features a compact 20 mm wide housing for standard DIN rail mounting. It accepts input signals from 2-wire and 3-wire SMART transmitters as well as 2-wire current sources. Specifically, this unit functions as a signal splitter that converts one field input into two galvanically isolated control-side outputs. This arrangement allows the KFD2-STC4-EX1.2O to drive two independent control systems from a single field device. For example, you can feed one output to your primary DCS while routing the second to a safety PLC or backup indicator. Moreover, the integrated test sockets enable loop checks without interrupting normal operation.
Core Value
The KFD2-STC4-EX1.2O delivers exceptional value through its combination of safety, flexibility, and space efficiency. Firstly, it provides intrinsic safety protection for field circuits located in explosive atmospheres. Moreover, its SIL 3 rating qualifies this module for use in safety instrumented systems up to the highest integrity level. Therefore, you can eliminate separate power supplies, isolators, and splitters by deploying this single device. Consequently, this approach reduces cabinet footprint and minimizes potential failure points. Besides, the transparent HART pass-through functionality enables remote instrument configuration and predictive diagnostics. This capability substantially decreases unnecessary field visits and simplifies ongoing maintenance.
Technical Insights
The KFD2-STC4-EX1.2O operates from a nominal 24 V DC supply, accepting a range of 20 to 35 V DC via the Power Rail or direct terminal connection. The field input accepts standard 0/4 to 20 mA signals from the connected transmitter. Meanwhile, each of the two output channels delivers a 0/4 to 20 mA signal into a maximum load of 550 Ω. Specifically, if your control system cannot provide the required 250 Ω HART load resistance, you can activate the internal resistor between terminals 8 and 9. Furthermore, this module delivers outstanding accuracy with a total deviation of ≤ 10 µA at 20 °C, which includes all calibration, linearity, and temperature effects. The HART communication frequency range extends up to 7.5 kHz, ensuring reliable digital data transmission even over longer cable runs. Additionally, the device offers a transmission gain of approximately 1.005, guaranteeing minimal signal loss through the barrier.
Installation & Maintenance
Mount the KFD2-STC4-EX1.2O onto a standard 35 mm DIN rail according to EN 60715 specifications. Snap the device onto the rail vertically to prevent any damage to the internal contacts. Crucially, you must connect loads to both output channels for proper device operation. If you leave one output open circuit, the transmitter supply voltage will drop by as much as 0.7 V, potentially affecting linearity. For routine maintenance, simply connect a HART communicator to the dedicated test sockets without breaking the loop. Always perform all wiring and disconnection procedures in a non-hazardous area. De-energize the device entirely before starting any troubleshooting or replacement work.
Buyer's Guide FAQ
1. What exactly does the KFD2-STC4-EX1.2O do?
The KFD2-STC4-EX1.2O powers SMART transmitters located in hazardous areas. It also receives one 4-20 mA input and splits it into two isolated output signals while preserving HART digital communication.
2. Can I use the KFD2-STC4-EX1.2O in a safety loop?
Yes, absolutely. This module is SIL 3 certified per IEC 61508. You can confidently deploy it in safety instrumented functions up to SIL 3.
3. Why must I connect both output loads on this device?
The KFD2-STC4-EX1.2O requires both outputs to be loaded for correct operation. An open circuit on one output will cause the transmitter supply voltage to drop by up to 0.7 V.
4. How do I perform HART communication with this module?
You can connect a HART communicator directly to the test sockets on the terminal block. Alternatively, you can enable the internal 250 Ω resistor between terminals 8 and 9 if your system requires additional load.
5. What are typical applications for the KFD2-STC4-EX1.2O?
Typical applications include splitting pressure or temperature transmitter signals to both a DCS and a safety PLC. It also provides intrinsic safety for field devices installed in Zone 0, 1, or 2 hazardous locations.
