The National Instruments SCXI-1128 (Part Number: 776572-28) is a versatile matrix/multiplexer switch module designed for high-voltage applications. It operates as a multiplexer in various configurations, accommodating one-link connections for expansive station structures, two-link setups for differential combinations, and three or four-link modes for resistive measurements such as resistance temperature detectors (RTDs) and thermistors. The SCXI-1128 features front-mounted SCXI terminal blocks that enable conversion to multiple matrix configurations, including a 1-wire 64x1 matrix, a 32x1 2-wire matrix, a 2x 4x8 matrix, or a 4x16x1 matrix. It is critical to ensure that connections do not exceed the module's maximum signal ratings to avoid potential damage to the connected SCXI chassis, host PC, and the module itself.

Users can configure the SCXI-1128 to function as a multiplexer/scanner, with options for 2-wire, 1-wire, or 4-wire channel configurations. In all modes, only one channel can be closed at a time. This module is rated for Measurement Category II and supports signal voltages of up to 300 VDC or 250 VAC. Technical specifications include a maximum switching power of 9 W, maximum switching current of 30 mA, a DC path resistance of less than 1.2 kΩ, a relay operation time of 0.25 ms (typical), a release time of 0.08 ms (typical), and a maximum scan rate of 1200 channels. A warm-up period of five minutes is recommended for optimal performance.

The SCXI-1128 is compatible with various software packages and application development environments, including the NI-SWITCH driver software, LabVIEW, and Measurement Studio. This compact module weighs 6 oz and measures 7.8 x 1.2 x 6.8 in. It operates within a temperature range of 0 °C to 50 °C and can be stored at temperatures between -20 °C and 70 °C, with a non-condensing relative humidity range of 5% to 85%. The SCXI-1128 adheres to several electrical safety standards, including IEC 61010-1, EN 61010-1, UL 61010-1, and CSA 61010-1.