The National Instruments 781986-25, also known as the PXIe-2725, is an 18-channel PXI Programmable Resistor Module designed for accurately simulating resistance-based inputs and outputs, such as potentiometers, resistance temperature detectors (RTDs), voltage dividers, and bridge elements. This module employs a network of relays to precisely adjust resistance across each channel, making it an ideal component for hardware-in-the-loop (HIL) validation. Its software interface accommodates inputs in both temperature and resistance units. The 781986-25 supports a maximum voltage of 60 VDC or 30 VACrms (CAT I) across channels and ground, with a maximum current rating of 0.3 A per channel and a power capacity of 0.25 W per channel. With an accuracy of 0.5% and a temperature coefficient of resistance (TCR) of 100 ppm, each channel operates within a resistance range of 1 Ω to 255 Ω, adjustable in 1 Ω increments. The module features a typical initial DC offset resistance of less than 1 Ω, which may increase to 3 Ω over time due to relay contact and trace resistances. For dynamic performance, the 781986-25 can simultaneously drive up to 161 relays, maintaining a relay operate/release time of 250 μs. The expected relay life is up to 1 × 10^8 cycles under low power loads (<50 mW) and approximately 1 × 10^6 cycles at full power load (<250 mW). Triggering is managed through PXI trigger lines <0...7>, requiring a minimum pulse width of 150 ns. Connectivity is facilitated via a 37-pin D-SUB connector on the front panel and two 2 × 2 Micro-Fit connectors dedicated for digital multimeter (DMM) ports. The module operates at a power requirement of 1.2 W at 3.3 V, with a maximum of 11 W at 12 V. Engineered to fit within one 3U PXIe/cPCI slot, the compact design measures 21.6 × 2.0 × 13.0 cm and weighs approximately 323 g. Suitable for indoor use, the 781986-25 operates effectively within a temperature range of 0 °C to 55 °C and can be stored in environments ranging from -20 °C to 70 °C. Compliant with numerous electromagnetic compatibility and safety standards, the device adheres to EN 61326-1, EN 55011, AS/NZS CISPR 11, FCC 47 CFR Part 15B, ICES-001 for emissions, and aligns with IEC 61010-1, EN 61010-1, UL 61010-1, and CSA 61010-1 for safety, ensuring robust performance in industrial applications.

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