Siemens 6ES5-440-8MA21 Digital Output Module 24V

Siemens 6ES5-440-8MA21 is a four-channel digital output module for the SIMATIC S5/ET 200U automation lineup. It provides four 24 V DC outputs, each capable of switching up to 2 A, enabling direct control of 24 V loads such as solenoids, relays, and other actuators in legacy Siemens systems. Designed for DIN-rail or backplane mounting in industrial control cabinets, it plugs into the S5/ET 200U I/O backplane to receive commands from the central controller and deliver switched 24 V to the connected devices. The 6ES5-440-8MA21 is documented as a 4×24 V DC/2 A digital output module within the ET 200U family, distinguishing it from other digital output variants in the same 6ES5-440/6ES5-441 lineup. Typical applications include modernization or expansion of older production lines where SIMATIC S5 controllers manage relays and solenoid actuators, valve control, or signal devices in automated equipment.