Siemens 6EC1661-0A Industrial Control Relay Module

Siemens 6EC1661-0A Industrial Control Relay Module is a SIMATIC C1 PCB-based relay output module featuring four isolated relay contacts, designed to translate PLC logic into controllable load switching. The unit ships in its original packaging and bears the Siemens part number 6EC1661-0A. As a four-output relay module, it provides four independent outputs suitable for driving external devices such as actuators or indicators in legacy automation setups that use the SIMATIC C1 family. This module is intended for installations where discrete relay outputs are required to interface a PLC with higher-power loads, offering a compact, plug-in interface that complements older Siemens automation configurations.