Stanford Research SIM923 Diode Temperature Monitor

The Stanford Research Systems SIM923 is a single-wide modular temperature monitor designed for precision measurements with Platinum Resistance Temperature Detectors (Pt RTDs) within the SIM900 Mainframe. The module employs a ratiometric half-bridge measurement technique with four-wire configuration to eliminate lead resistance effects, delivering up to four readings per second across the 20 K to 873 K range.

Technical Specifications

• Sensor type: Platinum RTDs (Pt-100, DIN 43760)


• Four-wire circuit (±I excitation, ±V sense leads)


• Ratiometric half-bridge with internal reference resistor


• Input resistance range: 0 Ω to 1400 Ω


• Reading rate: 4 readings/second maximum


• Current reversal capability for offset testing Excitation Source


• Selectable DC current sources: 10 µA and 1 mA


• 1 mA accuracy: ±0.1% with ±5 ppm/°C stability


• 10 µA accuracy: ±0.01% with ±5 ppm/°C stability


• Independent per-channel control with disable option Outputs and Display


• 4-digit LED display (single-channel, K or Ω selectable)


• Linearized analog output proportional to temperature


• Buffered raw sensor voltage output


• Analog output range: ±10 V (full-scale 10 K to 1000 K) Calibration


• Factory DIN 43760 curve pre-programmed


• Custom curve storage: up to 256 temperature-vs-resistance points in non-volatile memory


• Remote curve selection via command interface

Key Features

• Four-wire topology minimizes lead resistance contribution to measurement error


• Dual current-source flexibility accommodates low-power and high-precision requirements


• Current reversal diagnostics detect systematic voltage offsets


• Excitation disable reduces power dissipation in battery or low-power applications


• On-board calibration storage eliminates external lookup tables

Typical Applications

• Cryogenic temperature monitoring (20 K baseline)


• Materials characterization across wide thermal ranges


• Calibration and verification of secondary temperature standards


• Laboratory and industrial process monitoring

Compatibility & Integration The SIM923 integrates into the SIM900 Mainframe ecosystem, requiring clean, well-regulated ±5V and ±15 VDC supplies. Remote command interface enables automated measurement and curve selection in multi-channel systems.