PRS-330 Precision Programmable Resistance Box & RTD Simulator

The PRS-330 is the decade resistor you need for calibration labs and automated production environments

Very tight accuracy, almost no long term maintenance costs

  • Resistance range: 0.1 Ω to 20 MΩ with a Resolution of 1 μΩ or 6 digits
  • Lab grade accuracy (70 ppm + 1 mΩ): 1.5 times better than conventual manual decade resistors
  • Large color touchscreen, soft keys and intuitive interface promotes little to no training
  • Can be used as both a Manual or an Programmable unit in both calibration lab and production environments.
  • Comes standard with USB, Ethernet and IEEE interfaces and full LabView command structure, see manual and drivers for more details
  • If you do NOT own an 8.5 Digit DMM (Fluke 8508A or Keysight 3458) OR if you require an Ethernet or USB Interface this is the instrument for you

  • Virtually no maintenance cost, very simple to calibrate. If it drifts, it easily adjusts back to spec without costly repairs
  • High reliability relays, rated for 100 Million Switches
  • Rated for use at 0.5 W, for higher power consider the PRS-202 
  • Use for RTD applications is straightforward with built-in PT-100 and PT-1000 Tables, RTD values can be input in both °C, °F
  • Strong ac performance
  • No zero or switch resistance 0.1 Ω is 0.1 Ω
  • Front and rear binding posts for ease of connection
  • Sold with an industry leading 5 year warranty and Manufactured in the USA
  • About 10% lower in cost than the PRS-370 or its predecessor unit the PRS-300
  • If you already own, or are considering buying, an 8.5 Digit DMM you should strongly consider the PRS-370 instead of the 330
Priced at
The PRS-330 was designed with the right mix of features for to be efficient for both manual and automated application in both laboratory and production environments such as; calibration of resistance meters, calibration of temperature controllers and indicators, automated test systems requiring a precision resistive load.

With its wide resistance range and 6 digit resolution, the PRS-330 was designed to replace multiple decade boxes and reduce test time.

With its industry leading 5-year warranty all aspects of the PRS-330 focus on reliability, reduced ownership costs and simplicity out of the box.

User interface
The PRS-330 utilizes a large state-of-the-art color capacitive touchscreen which provides super fast response time. Even in low or bright light conditions, the display provides exceptional clarity with large fonts and easy-to-read menus.
The user interface also features softkeys and a numeric keypad allowing the use of the user interface without using the touchscreen.

Interface and drivers
The operation is both local using a color touch screen, soft keys, and numeric keypad or remote control with standard USB, Ethernet, and IEEE-488 interfaces. The versatility of USB, Ethernet or GPIB interfaces allows you to completely automate your testing.

Highest quality components
The programmable resistance box 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. Resistors are custom Z-foil and low inductance wirewound for low TC and excellent stability.

RTD calibration
Built-in tables for PT100 and PT1000 RTDs and direct resistance substitution makes the PRS-330 ideal for RTD (Resistance Temperature Detector) simulation. User-defined tables can also be created for use with other RTDs. The operator can enter temperature directly and the correct resistance will automatically be programmed.

No zero resistance. 0.1 Ω is 0.1 Ω
The PRS Series programmable resistance box 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.

Switching between resistance changes
The relays can be switched via fast, short or open. Fast switching changes resistance values with a switch time of less than 10 ms. Short and open allows a known state when resistance values are changed either manually or programmatically however more time is required between switching. Short switching introduces a short (0.1 Ω) in between resistance changes. Open switching introduces an open between resistance changes.

ac performance
The PRS-330 programmable resistance box is a precision resistance source with excellent characteristics of stability, temperature coefficient, and power coefficient. The use of low inductance wirewound and Z-foil resistors allows the PRS-330 to be used in ac applications with minimal resistance change below 1 kHz.

Resistor carousel
Built-in EIA "preferred value" resistance tables of 1% (E96), 5% (E24), 10% (E12) increments or user specified increment allows the PRS-330 to be used as a resistor carousel.

Further improve on accuracy to <15 ppm 
Additionally, if you own an 8.5 digit DMM, Fluke 8508A, 8588A or the Keysight 3458A, for no additional cost, the PRS-330 can be used as part of the PRS-DMM system which will further improve on the accuracy of the unit to   However, unlike the PRS-370 this requires a separate PC for operation.

If you own or consider buying one of these DMM's you should strongly consider the PRS-370 instead of the PRS-330

The Patented PRS-370 Programmable Resistance Standard can control an 8.5 digit DMM like Fluke 8508A, 8588A or the Keysight 3458A, and automatically adjust the source resistance to achieve an accuracy of <10 ppm without the need of an external computer

Calibration history
Calibration history of each internal resistor can be reviewed to show drift and performance. The calibration history data can be retrieved via SCPI command for further analysis.   Pressing a switch on the front panel allows access to calibration history and adjustment menus minimizing unauthorized access.

Cybersecurity statement
The PRS-330 contains a microcontroller, and runs proprietary firmware. The firmware can only be updated via a JTAG or similar cable and only accessed by removing the top cover of the instrument.   There are no facilities to update firmware via the USB, Ethernet or GPIB interfaces on the PRS-330.
Windows or Linux are not used in this product.  A factory reset is provided which will reset the PRS-330 back to factory default including calibration data history and all other data that can be saved by a user.

Optional Rack Mounting
The PRS Series programmable resistance box may be rack mounted to serve as components in measurement and control systems.

USB driver for Windows 7 and Windows 10
The USB interface uses a MCP2200 Driver. If the driver is not automatically installed by Windows this can be download and installed using the link below. 
For USB interface:  Download:
Unzip the file and follow instructions to install.

Ethernet interface
For Ethernet interface:  Download:
Unzip the file and follow instructions to install. The application allows the user to change IP address and communicate with the PRS. Please see PRS-330 instruction manual for more information.


(See datasheet for full specifications)
User interface:Color graphical capacitive touchscreen and numeric keypad display
Accuracy: ±(70 ppm + 1 mΩ) 4 Terminal
Minimum setting: 0.100 000 Ω
Resolution: 1 µΩ or 6 digits
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:
4 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 for both Fahrenheit and Celsius.
Adjustment: Automatic adjustment procedure utilizing a high precision DMM eliminates the requirement for manual trimming of resistors.
Front and rear connections each consist of 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: < 10 ms
Power requirements: 90 - 264 Vac , 47 - 63 Hz., 30 W. Max.
Remote Control:
USB: USB B female connector rear panel
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
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.