4WPB100 100 Ohm, 4-Wire PRT Bridge Terminal Input Module


The 4WPB100 provides completion resistors that allow your Campbell Scientific datalogger to measure a 100 ohm platinum resistive thermometer (PRT).

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Benefits and Features

  • Makes accurate measurement of 100-ohm PRTs simple
  • Easy to install or remove
  • Connects directly into datalogger input terminals
  • Compatible with most Campbell Scientific dataloggers


Detailed Description

4-Wire PRT Bridge Module Schematic
(Rf=100 Ω for the 4WPB100)

4WPB100-to-Sensor Hookup


Dimensions 1.5 x 1.5 x 2.7 cm (0.6 x 0.6 x 1.0 in.) for body with prongs
Weight 6 g (0.2 oz)

Current Limiting 10 kΩ Resistor

Tolerance ±5% (@ 25°C)
Power Rating 0.25 W

Completion Resistor (bulk metal foil)

Resistance (Rf) 100 Ω
Tolerance ±0.01% (@ 25°C)
Maximum Temperature Coefficient ±0.8 ppm/°C
Power Rating 0.25 W (@ 70°C)


Datalogger Considerations

The 4WPB100 uses two adjacent differential analog inputs; the first channel requires an adjacent analog ground channel to accept the "ground prong" of the 4WPB100. Not all datalogger terminal strips have this sequence on all channels, so please check your datalogger's wiring panel to confirm channel assignments, especially if you plan to use multiple Terminal Input Modules.

Newer CR10X Wiring Panels and the CR10XTCR Thermocouple Cover are deep enough to cover the datalogger input channels with a Terminal Input Module attached; older CR10TCRs are not deep enough.


When using CRBasic, the 4WPB100 is measured with the BrHalf4W Instruction followed by the PRT Instruction. When using Edlog, the 4WPB100 is measured with Instruction 9 (Full Bridge w/ Measured Compensation) followed by Instruction 16 (Temperature RTD).

Compatible Contemporary Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR9000X CR6 CR300 Series

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR5000 CR7X CR9000

*As shipped, the prongs on the 4WPB100 are too short to fit the CR7. If you're determined to use the 4WPB100 with a CR7, you can solder wire to the prongs, thereby extending their length.

Frequently Asked Questions

Number of FAQs related to 4WPB100: 3

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  1. Only one 4WPB100 is needed to measure the internal PRT in the radiometer.

  2. The CR1000 requires a 4WPB100 to measure the internal PRT. (Dataloggers such as the CR3000 and CR5000 have the necessary PRT bridge module built in to measure the PRT.) Note that the CNR4-L also includes an internal thermistor, which can be directly measured by the CR1000. Because of this, when using a CR1000, Campbell Scientific typically recommends monitoring the internal temperature of the CNR4-L using its internal thermistor instead of the PRT. 

  3. The 4WPB100, 4WPB1K, and 4WHB10K terminal input modules can be used instead of the 3WHB10K module. However, to maintain the enhanced accuracy of the four-wire half-bridge instruction, it is pertinent when adding the fourth wire to maintain the same resistance as the other three wires (same wire size and manufacturer). Note that simply adding a short jumper wire on the 4WPB100, 4WPB1K, or 4WHB10K modules to complete the fourth wire will not maintain the accuracy.

Listed Under

Common Accessory for the following products: