Product Overview

The Siemens 6ES5451-4UA14​ is a SIMATIC S5 Series Digital Output Module 451-4, delivering 32 floating (galvanically isolated) 24 V DC output channels at 0.5 A per channel, engineered in the S5 “compact” form factor for direct mounting in S5-90U, S5-95U, and S5-100U compact central racks as well as ET 100U and ET 200U distributed I/O nodes. Within the S5 modular I/O hierarchy, the 6ES5451-4UA14​ occupies a single compact-width slot—narrower than the wide-format modules that seat in S5-115U/155U UR racks—and drives 24 V DC field actuators such as solenoid valves, indicator beacons, interposing relay coils, VFD 24 V DC aux enable circuits, and stack-light segments, switching them from the S5 CPU process image on every OB1 scan.The defining architectural distinction of the Siemens 6ES5451-4UA14​ versus its sibling 6ES5441-7LA11​ (which is a wide-rack, non-floating 32×24V DC DO for S5-115U/155U) is twofold: form factor and galvanic isolation. The 451-4 is compact-width, targeting the S5-100U class where rack real estate is tight (e.g. skid-mounted equipment, small-machine control boxes, distributed ET200U nodes); and its 32 outputs are floating relative to the S5 backplane, meaning the 24 V DC load supply that feeds the DO field side can be a different PS than the rack’s L+ bus—critical in panels where the 24 V DC field load domain is segregated from the 24 V DC rack/sensor domain for noise or segregation reasons. The module uses a 20-pin front connector (compact footprint, versus the 48-pin used on wide-rack S5 modules) and draws modestly from the 5 V backplane.Officially discontinued by Siemens with no replacement listed (“cancelled without having any replacement product”), the Siemens 6ES5451-4UA14​ remains the correct native 32×24V DC floating DO for S5-100U compact cells and ET200U distributed nodes—rewiring to an S7-era DO (ET 200SP, etc.) would force a platform migration with STEP 5 → TIA requalification, a non-starter for GMP-ancillary, validated utility, or small-machine assets still running S5. For those plants, the 6ES5451-4UA14​ is a bill-of-material necessity kept as cold spare per compact rack.

Technical Specifications