Siemens 6ES5440-8MA21 | 8-Channel Digital Output Module

Isolated 8-Channel Output for SIMATIC S5 Systems

The 6ES5440-8MA21 digital output module provides eight isolated transistor outputs for the SIMATIC S5 product family. This non-floating module is specifically designed for S5-90U, S5-95U, S5-100U, ET 100U, and ET 200U systems . It converts weak PLC logic signals into robust 24 V DC field signals for driving actuators . This module serves as a reliable interface between the controller and industrial loads.

Technical Specifications

Parameter	Specification
Manufacturer	Siemens
Product Line	SIMATIC S5
Model	6ES5440-8MA21
Module Type	Digital Output Module (non-floating)
Output Channels	8 (transistor)
Output Voltage	24 V DC (20.4 – 28.8 V range)
Output Current	0.5 A per channel
Response Time	< 1 ms (typical)
Isolation	Optoelectrical (output vs. logic)
Short-Circuit Protection	Electronic (per channel)
Weight	Approx. 0.2 kg
Protection Rating	IP20
Mounting	Rack slot (occupies one slot)
Indicators	8 x channel status LEDs, 1 x SF group fault LED
Operating Temperature	0°C to 60°C
Compatibility	S5-90U, S5-95U, S5-100U, ET 100U, ET 200U
Certifications	CE, UL, CSA

Protection and Diagnostic Features

The 6ES5440-8MA21 incorporates electronic short-circuit protection on each output channel . This protection automatically disables the faulty channel and signals the fault via the SF group LED. Consequently, this feature prevents module damage and simplifies troubleshooting. The module also protects against overload conditions, enhancing system reliability .

Physical Characteristics and Installation

Weighing approximately 0.2 kg, this compact output module occupies a single slot in the S5 or ET 200 rack . Its standard S5 module format allows easy integration into existing systems. The front panel features eight LED indicators that display the real-time status of each channel. In addition, a green LED indicates the presence of the external load power supply.

System Integration and Compatibility

The 6ES5440-8MA21 module supports S5-90U, S5-95U, S5-100U, ET 100U, and ET 200U configurations . It connects to the controller via the backplane bus for seamless data exchange. Users can wire field devices directly to the screw terminals on the module. This module proves ideal for driving relays, solenoid valves, and indicator lamps in medium-scale automation tasks.