Product Overview

The 6ES5458-7LB11​ is a digital output module from the Siemens SIMATIC S5 458 subseries, configured as an 8-channel relay output (8RO) variant with individual galvanic isolation per contact and a robust 5 A / 115–230 V AC rating per channel. Designed specifically for the S5-115U and S5-115U/F central-processor racks (the “-7” prefix in the ordering code denotes compatibility with S5-115U/F, S5-135U, and S5-155U central racks rather than the compact 90U/100U form factor), the 6ES5458-7LB11​ sits in the larger S5 rack slot envelope and delivers significantly higher contact current capability than the compact 452-series 4-relay sibling. Each channel uses a Siemens V23157-006-A402 electromechanical relay with SPDT architecture (common / NO / NC accessible via the S5 front connector), and the module integrates SIOV-S07-K275 varistor contact protection to suppress inductive kickback from contactor coils and solenoid valves—a detail that distinguishes the 458 from leaner S5 relay DO cards.The 6ES5458-7LB11​ is positioned for process-grade S5 installations: S5-115U/F racks in boiler MCC rooms, S5-135U material-handling masters, and S5-155U process cells where the DO load isn’t just 24 V DC pilot devices but 115 V AC or 230 V AC contactor coils, motor-starter aux circuits, and HVAC actuator legs that demand both higher current per contact and channel-to-channel isolation. Siemens placed the 6ES5458-7LB11​ into PM490 status effective 01.10.2020—product discontinued, without a designated replacement—making it, like much of the S5 45x relay family, a pure MRO/spare-stocking line item for plants that have chosen to run S5 central racks to end-of-life rather than migrate to S7-400 or S7-1500.Technically the 6ES5458-7LB11​ consumes ~50 mA from the S5 5 V backplane (logic/latch side) and ~200 mA from the rack’s 24 V L+ relay supply, with total module loss around 4 W. Eight relays in one slot means the module is backplane-current-aware in a fully loaded S5-115U/F rack (which typically carries a 115U PSU of 5 A / 24 A rating), but the density payoff is clear: one 6ES5458-7LB11​ replaces two 4-relay compact cards if the rack format permits the longer “-7” footprint.

Technical Specifications

Main Features and Advantages

8-channel 5 A relay density in a single S5-115U/F slot.​ The 6ES5458-7LB11​ packs eight SPDT relay contacts into one central-rack module, each rated 5 A at 250 V AC resistive—double the per-contact current of the compact 452-series (2.5 A@30 V DC / 5 A@250 V AC but in a 4-relay footprint). For S5-115U/F process racks where a single panel might need to switch six 230 V AC contactor coils plus two beacon-strobe legs, one 6ES5458-7LB11​ covers it without eating two or three slots. In a fully loaded 115U rack (up to 8 I/O slots + CPU + PSU + IM), slot economy matters.Per-contact galvanic isolation with SIOV varistor protection.​ Unlike transistor or triac DO modules that share a common 0 V reference, every relay on the 6ES5458-7LB11​ floats independently—contact-to-contact and contact-to-backplane. Siemens added a SIOV-S07-K275 varistor across each contact pair, which clamps inductive kick from contactor coils and solenoid valves at switch-off. This is a meaningful reliability differentiator in motor-control MCC applications where the 6ES5458-7LB11​ is often asked to switch 230 V AC starter-coil legs that lack external snubbing. The varistor buys contact life; without it, the same inductive energy welds NO contacts within months of high-cycle duty.