Stanford Research Systems SIM923A Overview
The SIM923A RTD Monitor continuously reads a single sensor and provides both digital and analog outputs. Based on the modular SIM platform, it provides high performance capability in a small footprint. The SIM923A has selectable 10 A and 1 mA current sources to provide sensor excitation. Sensor resistance is determined ratiometrically with a half-bridge circuit consisting of the sensor and an internal reference resistor. The current to the sensor can be reversed by the user to test for any offset. Measurement results can be displayed in either kelvins or ohms. The SIM923A employs four-wire measurement circuits (ToneI excitation leads, V sense leads), making readings insensitive to series lead resistance. Sensor excitations can be disabled to reduce power dissipation at sensitive cryogenic stages. Measurements are performed at five readings per second. The scaled analog output (Tone10 V) produces a voltage proportional to measured temperature, with a full-scale range from 10 K to 1000 K
