Signametrics SM4042 Programmable Logic Controller Module

The Signametrics SM4042 is a PCI-based 40-channel relay multiplexer that plugs into a PC's PCI bus to provide dense, electromechanical signal routing for test and measurement applications. As part of Signametrics’ SM40x family (which also includes the SM4020, SM4022 and SM4040), the SM4042 offers 40 independently controllable relay channels, enabling quick reconfiguration of connections between test instruments, sensors, and signal generators without software-level analog multiplexing. The module is designed for high-performance switching in automated test equipment and data-acquisition benches where reliable channel-to-channel routing and repeatable contact closure are essential. The device adheres to the standard PCI form factor and uses Signametrics’ relay-multiplexer architecture described in the SM4020/22/40/42 data sheet, which documents the 40-channel configuration and PCI interface across the family. Typical applications include signal routing for test rigs, laboratory automation, and hardware-in-the-loop setups where multiple signals must be redirected through external instrumentation. The SM4042 is a plug-in component intended for integration into PC-based test systems, offering a compact solution to multiplex dozens of signals via a single PCI card rather than wiring separate relays externally.