Description
The Action Instruments Ultra Slimpak G408-0001 (often managed under the Eurotherm / Invensys parent brand) is a high-density, field-configurable DC input signal isolator and conditioner. Housed in an ultra-slim 12.7 mm housing footprint, it isolates and converts a wide matrix of DC voltage or current signals into standard industrial process loops.
Technical Specifications
| Parameter | Value |
| Manufacturer | Action Instruments (Eurotherm / Invensys) |
| Product Series | Ultra Slimpak |
| Model Number | G408-0001 |
| Power Input | 9 to 30 VDC nominal (1.5 W typical / 2.5 W max) |
| Isolation Barrier | 1800 VDC between input, output, and power circuits |
| Field-Configurable Inputs | 12 Voltage ranges (10 mV to 100 V)
6 Current ranges (1 mA to 100 mA) |
| Field-Configurable Outputs | Unipolar only: 0–5 V, 0–10 V, 0–1 mA, 0–20 mA, or 4–20 mA |
| Factory Default Setting | 4–20 mA Input / 4–20 mA Output (unless specified custom) |
| Operating Temperature | 0°C to 55°C (32°F to 131°F) |
| Enclosure Mount | Standard 35 mm DIN rail bracket |
Field Experience & Engineering Insights
Strict Configuration Warning
⚠️ CRITICAL HAZARD: Do not attempt to alter the internal DIP switch positions while the module is powered. Changing the internal routing matrices on switches SW1 or SW2 while an active 9–30 VDC supply loop is energized will inject localized cross-currents into the ASIC processing channel, causing immediate and permanent hardware failure. Always de-energize the entire module before configuring or re-ranging.
Dynamic Input Adjustments & Tuning
The G408 provides an incredibly flexible 50% zero offset and 50% span turn-down capability via the front-facing precision trim potentiometers.
- Custom Ranging: This allows you to compress standard ranges down to capture tighter process details. For instance, you can select the standard 0–2 mA input switch arrangement, but turn it down via calibration to execute a full 4–20 mA output swing based on an input of only 1–2 mA.
- Bipolar Limitations: The
G408-0001version handles unipolar and centered bipolar inputs, but it only outputs standard unipolar currents/voltages. If your application requires a true bipolar output (e.g., -10 V to +10 V), you must procure the sister variant model, G408-1001.
Smart Diagnostic LED Flashing
The green LED indicator positioned on the faceplate acts as a dual-function system monitor rather than just a simple power indicator:
- Solid Green: Power rail is healthy; the input is tracking cleanly inside normal operating bounds.
- Flashing at 8 Hz: The incoming DC input signal is floating in an over-range state exceeding 110% of the full-scale setting.
- Flashing at 4 Hz: The incoming DC signal is dropped in an under-range fault state falling below −10% of the selected spectrum.
Thermal Management Array
While the 12.7 mm width allows you to pack dozens of signal conditioners tight onto a single DIN rail, stack density can lead to heat traps. If you are mounting 5 or more modules side-by-side on a vertical DIN rail orientation, you must leave spacing gaps, use a forced-air circulating fan, or slide an external Action Instruments HS01 heat sink plate between modules to prevent accelerated thermal drift or lifespan degradation.
Frequently Asked Questions
How do I accurately calibrate the module after changing the DIP switches?
Set up a precise DC signal simulator at the input terminals and hook up a calibrated multimeter to the output terminal loop. Allow the module to warm up for 1 to 2 hours inside its final enclosure environment to reach thermal equilibrium before adjustment. First, inject your absolute minimum target input and adjust the Zero pot until the meter reads the exact low-end output. Next, inject your maximum scale input and turn the Span pot to trim the high-end output. Repeat this pass twice for maximum precision.
Why is my loop showing erratic readings despite a stable input signal?
Check the system grounding configuration. If your field sensors and your downstream PLC/DCS chassis are grounded at separate physical locations across the plant, a high voltage potential difference can bypass lower-grade isolators. The G408 protects against this with a hefty 1800 VDC galvanic isolation matrix, but ensure that any shielded cables used are only grounded at one single termination end to avoid breaking the sensor’s isolation bubble.
