The IET Labs PRS-300 Programmable Resistance Substituter is a high-precision, lab-grade decade resistor and RTD simulator designed to automate manual resistance testing. Offering an accuracy of ±(70 ppm + 1 mΩ) and an expansive resolution down to 1 μΩ, it significantly minimizes test times by replacing multiple manual decade banks in high-accuracy workflows

Resistance Range: 0.1 Ω to 20 MΩ.
Resolution: 1 μΩ or 6 digits.
Accuracy: ±(70 ppm + 1 mΩ) 4-Terminal.
Stability: ±50 ppm/year.
Maximum Load Limits: 2 A max current, 200 V (peak), 0.5 W max power handling.
Thermal EMF: < 15 μV, minimizing measurement drift.
Resistor Construction: Built using low thermal-EMF relays with gold-clad silver-alloy contacts and precision wire-wound/metal foil resistors.
RTD Simulation: Features built-in PT100 and PT1000 lookup tables. Operators can key in a temperature value directly, and the instrument automatically shifts to the correct resistance. Custom tables can also be configured for other temperature sensors
PRS-DMM Integration: When paired with the optional PRS-DMM Software package, the hardware uses an active feedback loop with an 8.5-digit digital multimeter (such as a Fluke or Keysight standard) to adjust and trim values dynamically, driving true systemic accuracy to < 20 ppm.
Interfaces & Automation: Includes a front panel numeric keypad for manual operations. For automated test environments (ATE), it supports USB (via FTDI drivers), GPIB (IEEE-488.2), and Ethernet control options using SCPI commands
Common Applications
- Calibrating high-end digital multimeters (DMMs) and meters.
- RTD temperature sensor simulation and transmitter verification.
- Automated industrial testing, circuit tuning, and power supply load testing.

IET PRS-300 PROGRAMMABLE RESISTANCE SUBSITUTER | VERSION 2.1