Application Scenarios
A municipal water district in Bavaria runs a network of 14 unmanned stormwater lift stations, each originally built around a LOGO! 12/24RCE CPU. The design was tidy — until a new environmental regulation forced the addition of a third float switch per wet well plus a standby sump pump contactor. The base CPU’s onboard I/O was already fully allocated to the existing duty-pump VFD, siren, and SCADA telemetry. Rather than rip-and-replace the entire controller, the district’s panel builder simply clicked a Siemens 6ED1055-1MB00-0BA1 onto the right-side bus of each LOGO! 8 rack. The four new DI points absorbed the extra float switches; the four relay outputs drove the standby contactors and a local beacon — all switched at 230 V AC despite the LOGO! riding on 24 V DC control power. Commissioning took under ten minutes per station: no addressing, no DIP switches, just LOGO! Soft Comfort auto-detecting the expansion. Six months later, not a single spurious trip — and the district avoided a five-figure CAPEX round by leaning on a €60 expansion card.
Parameter
| Main Parameters | Value/Description |
|---|---|
| Product Model | 6ED1055-1MB00-0BA1 |
| Manufacturer | Siemens (LOGO! 8 Series) |
| Product Category | Digital I/O Expansion Module |
| Marketing Name | LOGO! DM8 12/24R |
| Digital Inputs | 4 channels, 12 / 24 V DC (10.8–28.8 V range) |
| Digital Outputs | 4 channels, relay type, 5 A (resistive) / 3 A (inductive) |
| Supply Voltage | 12 / 24 V DC (via LOGO! base bus, no separate PSU needed) |
| Mounting | 35 mm DIN rail, 2 TE width |
| Dimensions (W × H × D) | 36 × 90 × 55 mm |
| Operating Temperature | 0 °C to +55 °C |
| Protection Rating | IP20 (control-cabinet install) |
| Short-Circuit Protection | None — external fuse required on each relay output |
| Certifications | CE, UL, CSA, FM, Marine; IEC 61131 / VDE 0631 |
Technical Principles and Innovative Values
Innovation Point 1: Zero-wiring bus expansion. The 6ED1055-1MB00-0BA1 connects to a LOGO! 8 base module (or to another expansion on its left) through a molded 8-pin bus connector. Power, input scanning, and output commands all travel across that backbone — no separate 24 V feed, no parallel wiring, no address dip-switches. The base CPU simply sees “8 more I/O points” at the next scan.
Innovation Point 2: Mechanical coding prevents voltage-family mix-ups. Siemens molds a physical key profile on the bus connector that stops a 12/24 V DM8 from mating to a 115/230 V DM8 or AM analog module. That sounds trivial until you’ve seen a panel where someone forced a 24 V input card onto 120 V bus and cooked it — the 6ED1055-1MB00-0BA1 makes that impossible by design.
Innovation Point 3: Relay outputs decouple control voltage from load voltage. While the input side lives at 12/24 V DC, each relay output is galvanically isolated and can switch AC loads up to 250 V. That means one compact 2-TE card can read 24 V DC float switches and simultaneously drive 230 V AC motor contactors — a sweet spot for pump panels, HVAC staging, and small conveyor interlocks.
Application Cases and Industry Value
Beyond the stormwater lift stations, a commercial bakery in the Netherlands used the Siemens 6ED1055-1MB00-0BA1 to add proofing-room humidity dampers and alarm horns to an existing LOGO! 8 proofing-oven controller. Previously the plant had daisy-chained a separate 8-relay interposing block off the LOGO! base outputs, creating a tangle of terminal-block wiring that confused junior techs during night shifts. Swapping to the 6ED1055-1MB00-0BA1 collapsed that external relay bank into the LOGO! DIN rail footprint, cut panel wiring time by roughly 3 hours per oven skid, and gave the maintenance team LED-per-channel diagnostics right on the expansion faceplate. The plant manager’s post-retrofit note: “Same LOGO!, twice the flexibility, zero rewrite.”
Related Product Combination Solutions
Building a LOGO! 8 panel around the 6ED1055-1MB00-0BA1? These companions cover most small-machine I/O mixes:
- 6ED1052-1MD00-0BA6 — LOGO! 12/24RCE base CPU (the “host” this expansion snaps onto; Ethernet, web server, microSD).
- 6ED1055-1MA00-0BA1 — LOGO! AM2 analog expansion (2 AI) for temperature, pressure, or 0–10 V pot inputs alongside your digital points.
- 6ED1055-1MD00-0BA1 — LOGO! DM16 12/24R (8 DI / 8 DO relay) when 4+4 isn’t enough and you need the bigger sibling of the 6ED1055-1MB00-0BA1.
- 6ED1055-1FB00-0BA1 — LOGO! DM8 230R (4 DI 230 V / 4 DO relay 230 V) for mains-voltage input applications.
- 6ED1072-1AX00-0BA1 — LOGO! TDE text display, for local setpoint adjustment and alarm acknowledgement at the panel door.
- 6ED1057-1AA00-0BA0 — LOGO! CMK2000 communication module, if you need to bridge the rack into Profinet or Modbus TCP later.
