PRS-DMM Programmable Self-Adjusting Resistance Standard

  • Patent pending
  • Software leverages the accuracy of an 8.5 digit DMM, with the versatility of the PRS-300 Programmable Resistor to make the most revolutionary programmable standard resistor ever manufactured
  • Resistance Range: 0.1 Ω to 20 MΩ
  • Resolution: 1 μΩ
  • Accuracies better than 20 ppm; source resistance with the same accuracy that your 8.5 Digit DMM can measure.
  • All you need to do is enter the target resistance. The software uses the DMM to measure the resistance being sourced by the PRS-300 and readjusts the source resistance as close as possible to the target resistance typically better than 10 ppm.
  • Software automatically provides the measurement uncertainties of every measurement
  • When you buy PRS-300, there is no additional cost for this PRS-DMM software
  • If you already own a Fluke 8508A or a Keysight 3458A 8.5 Digit DMM, this is the most cost effective way to have an precision resistance source in your lab
  • No need to worry about resistors going out of tolerance (long term stability) or accounting for zero/switch resistance
  • No calibration or maintenance costs required, when used with an 8.5 digit DMM
  • Will have lower long-term operating cost than traditional manual decade resistors like 1433 or HARS-X
  • Very easy to use with little to no training required; no need to understand programming
Priced at

The PRS-DMM is a software package, included at no additional charge with a PRS-300, that significantly improves the performance of a PRS-300 allowing it to be a self-correcting, programmable resistance standard.  

The PRS-DMM is a precision resistance source with excellent characteristics of stability that leverages a 8.5 digit DMM to automatically adjust the PRS-300 closer to the target source resistance value. This improves the basic accuracy of the PRS-300 from 70 ppm to better than 20 ppm. The PRS-300 uses a combination of series and parallel resistors that allows the target resistance to be changed by as little as 1 μΩ.

The PRS-DMM is easy to use with your existing Fluke 8508A Bench DMM or Keysight 3458A DMM. The PRS-DMM configures and performs measurements with the 8.5 digit DMM via GPIB. The user interface allows the user to enter the target resistance value, the resistance is then measured with the DMM and the PRS-300 is adjusted to provide a very accurate resistance value better than 20 ppm from the target value.

The main screen shows the desired resistance value or temperature can also be shown for RTD calibration. The DMM is connected to the output of the PRS-300. The Adjust button starts the adjustment process. The PRS-300 is programmed for target resistance and the DMM is configured to perform a resistance measurement. The resistance measurement is read back from the DMM and compared with the target resistance value. This programming of the PRS-300 and reading of the resistance value from the DMM continues until the resistance reading is within the required accuracy. A screen is then shown showing the measured resistance from the DMM, delta from target resistance in ppm and uncertainty of the measurement based upon accuracy tables for the Fluke 8508A or Keysight 3458A.
PRS-DMM Main Screen
The PRS-DMM also allows has an additional feature that allows for automatic trimming for the PRS-300 to bring the unit back to factory specifications. The PRS Series programmable resistance decade resistor employs very low resistance, low thermal emf relays with gold-clad silver-alloy contacts. A special design keeps contact resistance to a minimum. The gold plating keeps the silver contacts from becoming tarnished when unused, or when only low currents are passed through them. This is most often the case when only minute test currents are drawn by digital multimeters and other test instruments. Contact resistance remains low and repeatable through the use of multiple contacts.

The PRS-300 Programmable Resistor employs, high-quality gold-plated tellurium-copper five-way binding posts serve to minimize the thermal emf effects, which would produce errors in dc resistance measurements. All other conductors within the instrument, as well as the solder employed minimizes thermal emf problems.

The PRS Series Programmable Resistor may be rack mounted to serve as components in measurement and control systems.

The PRS-DMM software can be downloaded at this link PRS-DMM Software Download . This installs the LabView application and run-time engine.

Watch a video about the
PRS-DMM Programmable Self-Adjusting Resistance Standard


(See datasheet for full specifications)

User interface:Numeric keypad to enter resistance value with digital display
Accuracy: Better than 20 ppm. As good as the DMM
Minimum setting: 0.1 Ω
Resolution: 1 μΩ
Range: 0.1 Ω- 20 MΩ
Stability: ±50 ppm/year
Thermal emf: < 15 μV
Maximum Load: 2 A, 200 V (peak), 0.5 W whichever applies first
Resistors: Precision wire-wound and metal foil
RTD Tables:
3 RTD tables can be entered into memory to allow user selection of temperature and the correct value of resistance will automatically be programmed. PT100 and PT1000 tables are pre-programmed into memory.
Adjustment: Automatic adjustment procedure utilizing a high precision DMM eliminates the requirement for manual trimming of resistors.
4 low-emf, gold-plated, tellurium-copper 5-way binding posts are used for HI and LO terminal pairs for CURRENT and SENSE. GND binding post is connected to the case and to earth ground.
Switching time: <1 second per change
Power requirements: 90 - 264 Vac , 47 - 63 Hz., 30 Watts Max.
Bench model: 43 cm W x 8.9 cm H x 33 cm D (17" x 3.5" x 13") in front of panel: 3.8 cm (1.5").
Bench model: 4.0 kg (9 lb); Rack model: 4.5 kg (10 lb);
weight specifications are nominal.
Remote Control:
USB: USB interface standard on rear panel
Remote Control Options:
GPIB standard 24 pin connector, conforms to IEEE- 488.2; SCPI 1994.0 command set; Hardware or software configurable addressing range of 1 to 30.
IEEE 802.3 compliant, Speeds 10 BaseT (10 Mb/s) and 100 BaseT (100 Mb/s), IP Address Static or DHCP, Factory setting static