National Instruments 781986-27 Programmable Resistor Module 

National Instruments part number 781986-27 is an identifying part number for the PXIe-2727, a PXI Programmable Resistor Module with 9 Input Channels all with 16-bit resolution. The NI 781986-27 is a test module designed to simulate resistance-based inputs and outputs, such as potentiometers, resistance temperature detectors (RTDs), voltage dividers, and bridge elements. It programmatically controls a series of relays to adjust the resistance across each channel of an I/O connector. This capability makes it ideal for simulating environmental conditions in hardware-in-the-loop (HIL) validation. 

The software offers a user-friendly interface that accepts inputs in units of temperature or resistance, allowing precise configuration of the resistance across each channel. For channels set between 20 Ω and 64 Ω, the accuracy is less than 5.0%. For channels set between 64 Ω and 255 Ω, the accuracy improves to less than 2.0%. Specifically, for channels of the 781986-27set between 20 Ω and 40 Ω, the accuracy is less than 10.0%; for channels set between 40 Ω and 120 Ω, it is less than 5.0%; for channels set between 120 Ω and 400 Ω, it is less than 2.0%; and for channels set between 400 Ω and 16,000 Ω, the accuracy is less than 1.0%. 

Channel accuracy depends on the total resistor accuracy, relay and trace path resistance, and temperature effects. The module's front panel features a 37-pin D-SUB connector, ensuring versatile and reliable interfacing with external devices and systems. Additionally, it includes a 2 × 2 Micro-Fit connector designated for the DMM port, providing secure and efficient connectivity for digital multimeter (DMM) applications. Regarding power requirements, the 781986-27 operates with a power input of 1.2 W at 3.3 V, and it can draw a maximum of 11 W at 12 V, accommodating various power supply configurations and ensuring optimal performance under different operational conditions.