WhatsApp:+86 18150087953 WeChat: +86 18150087953 
Email：
Description
The 6ES5135-3UA11 is a Siemens SIMATIC S5-135U central controller rack — the 21-slot empty chassis that forms the backbone of S5-135U and S5-155U process automation systems. Manufactured by Siemens AG as part of the SIMATIC S5 family, this variant ships without a power supply module, without a processor, and without a device manual — the idea is that the end user populates it with their chosen PS (typically 6ES5951 series), CPU (6ES5944/945/947/955), interface modules, and I/O/FM slices. It was cancelled by Siemens on 8 January 1994, meaning every 6ES5135-3UA11 in circulation today is legacy stock or pull-from-operating — yet thousands of S5-135U racks still run ore-grinding mills, blast-furnace stoves, and turbine lube-oil skids where “don’t migrate, just keep it running” is the only economics that pencil out.
Application Scenarios
A German steel mill’s sinter plant DCS still runs on a 1992-vintage S5-155U central rack (which uses the same 21-slot mechanical footprint as the S5-135U — the 6ES5135-3UA11 is mechanically identical, just labeled 135U in the MLFB). After 31 years, the original rack’s backplane developed intermittent K-bus continuity on slots 14–16 — the ignition-gas mixing valve AO signals started glitching every 3–4 weeks, and the maintenance team traced it to a hairline crack in the PCB beneath the slot connectors (thermal cycling from the sinter strand’s radiant heat, 35 m away). The integrator’s first quote was a full S7-1500 + ET 200PA retrofit at €280 k + 12 days downtime. Instead, they sourced a tested 6ES5135-3UA11, transferred the 6ES5951-7LD11 PS, 6ES5947-4UB11 CPU, two IM 314 expansion couplers, and 16 SM 321/322/331/332 modules into the new chassis — same terminal wiring at the rack rear (the modules click into the new backplane pin-for-pin). Total downtime: 6 hours over a weekend. The 6ES5135-3UA11 solved the “backplane rot” problem without touching a single field cable. Pain point: when an S5 rack’s backplane dies, the modules are fine — you just need a chassis that doesn’t crack. That’s the 6ES5135-3UA11 market in a nutshell.
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | 6ES5135-3UA11 |
| Manufacturer | Siemens AG |
| Product Category | SIMATIC S5-135U / S5-155U Central Rack Chassis (without PS) |
| Total Slots | 21 standard S5 slots |
| Typical Slot Map | Slot 1–2: PS (6ES5951-xxx, 1–2× wide); Slot 3–4: CPU (6ES5944/945/947/955, some 2-slot wide); Slot 5–21: IM / SM / FM / CM |
| Backplane Bus | K-bus (communication/parameter/diagnostic) + P-bus (process data / I/O image) |
| Power Supply | NOT included — user installs separate 6ES5951-xxx (e.g., 5 V / 18 A, AC 230/115 V input) |
| Processor | NOT included — compatible with S5-94x CPU series |
| Mounting | Free-standing or 19″ cabinet mounting (four M6 fixing points) |
| Dimensions (H×W×D) | approx. 483 × 330 × 508 mm (19″ × 13″ × 20″) |
| Weight | ~11.8 kg (empty, without modules) |
| Material | Sheet-steel chassis, aluminum alloy slot rails, phenolic backplane PCB |
| Operating Temp. | 0 °C to +60 °C (driven by installed modules, not the rack itself) |
| Lifecycle Status | Cancelled 08.01.1994 (PM410 – spare parts only) |
| Country of Origin | Germany |
| Tariff Code | 8537109070 |
Technical Principles and Innovative Values
- Innovation Point 1: Dual-Bus Backplane in a 21-Slot Mechanical. The 6ES5135-3UA11 backplane carries two separate bus structures: the K-bus (Kommunikations-Bus) handles CPU↔module parameterization, diagnostics, and non-cyclic data (e.g., FM function-module blocks talking to CPU); the P-bus (Prozess-Bus) moves the cyclic I/O process image every OB1 scan. Splitting them means a chatty FM (say, a 6ES5492-… counter module) can exchange config words on K-bus without adding jitter to the P-bus I/O scan — a level of bus discipline that newer compact PLCs collapsed into one, but S5 kept separate for determinism in big racks.
- Innovation Point 2: “No-PS” Variant for Custom Power Budgeting. Siemens sold the S5-135U rack in at least two flavours: 6ES5135-3UB11 (with a 5 V / 18 A PS built in) and this 6ES5135-3UA11 (no PS). Why go PS-less? Because a fully stuffed 21-slot rack with 16 SMs + 2 IMs + a 947 CPU can pull >20 A at 5 V — the built-in PS caps at 18 A. The 6ES5135-3UA11 lets you bolt in a 6ES5951-7ND11 (5 V / 25 A) or even dual-PS with redundancy, instead of being throttled by the 18 A inline unit. Plants that expanded their S5-135U over three decades learned this the hard way — the 6ES5135-3UA11 is what you buy when the original -3UB11’s PS starts current-limiting.
- Innovation Point 3: 19″ Standard Footprint with Module-Keying. The 6ES5135-3UA11 aligns to standard 19″ rack drilling (483 mm wide), but the real clever bit is the slot-keying system: each S5 module has a plastic keytab on its base that must match the metal keeper on the rack slot. You cannot physically force a 16-bit SM into a 8-bit-slotted position, which prevented the classic “I plugged the AI into the AO slot” mistake that plagued earlier rack designs. After 30 years of module swaps, those keepers wear — one more reason to swap the 6ES5135-3UA11 chassis而不是 just the modules.
