Application Scenarios

In a municipal water-pumping station retrofitted with ET 200SP on PROFINET IRT, the original panel designer had specced transistor DOs for everything — including three 24 V DC lubrication-pump starter coils and two 24 V AC solenoid locks on the chemical-dosing skid. The problem surfaced during commissioning: the 24 V AC solenoids (transformer-derived, slightly dirty waveform) didn’t present a clean “1” load to the transistor DOs, and one channel blew its output stage within two weeks of cyclic duty. The fix was surgical — swap the DQ 8×24 V transistor submodule for a Siemens 6ES7132-6GD51-0BA0​ on the same BU A0 base. The four CO contacts cleanly handled the mixed 24 V DC pump coils + 24 V AC solenoid locks, and the channel-to-channel galvanic isolation (707 V DC tested) kept the inductive kick from the pump starter auxiliary contacts from talking back to the PN bus. More usefully, the station’s SCADE logic was re-mapped so that two of the four relays ran in redundant-parallel (“for redundant control of a load” per Siemens spec) on the lead-lube pump — if one contact weld occurred, the second path still carried. During a scheduled lubricator overhaul six months later, the maintenance crew pulled the 6ES7132-6GD51-0BA0​ live (BU base stayed powered, field wires untouched) and snapped a spare in — zero PN watchdog, zero pump trip. For this skid, the 6ES7132-6GD51-0BA0​ wasn’t an upgrade — it was the correction.

Parameter

Note: Unlike the DQ transistor siblings, the 6ES7132-6GD51-0BA0​ has no per-channel diagnostic LED — only green per-channel “status” (ON = contact energized) + a shared DIAG LED for module-level faults (supply voltage missing, etc.). Channel-level wire-break / short diagnostics are Not Available (relay physics). This is expected behavior, not a limitation.

Technical Principles and Innovative Values

• Innovation Point 1 – 24 V UC “Universal Contact” in 15 mm.​ The “UC” in RQ CO 4×24VUC/2A stands for universal contact — the relay’s NO/NC/N-COM triad switches 24 V AC or 24 V DC up to 2 A without derating. In a mixed skid where a 24 V DC pump starter and a 24 V AC door-interlock solenoid share the same submodule, the 6ES7132-6GD51-0BA0​ eliminates the “transistor-DO-can’t-do-AC” headache. One spare model covers both duties.
• Innovation Point 2 – Triple Galvanic Isolation in a 30 g Package.​ Each of the 4 CO contacts is isolated channel-to-channel and from the ET 200SP backplane and from the electronics supply — 707 V DC type test. In practice, this means you can land a slightly dirty 24 V AC transformer-fed load on Ch1 and a clean 24 V DC switched-mode pump coil on Ch2, on the same 6ES7132-6GD51-0BA0, without cross-talk. Transistor DOs in the same footprint can’t offer this.
• Innovation Point 3 – Redundant-Parallel for Control Loads.​ The 6ES7132-6GD51-0BA0​ explicitly supports “parallel switching of two outputs for redundant control of a load” (Siemens datasheet calls this out). Wire two of the four CO contacts in parallel to pilot a single critical actuator — if one contact welds, the second still closes. This is a differentiator vs. the lighter DQ 8×24 V transistor submodule, which doesn’t encourage parallel-for-redundancy on relay-class loads.
• Innovation Point 4 – Substitute Value Output + QI Byte.​ Like all ET 200SP “ST” submodules, the 6ES7132-6GD51-0BA0​ supports a substitute (replacement) value that the controller writes to the output if the module detaches from the IO controller (CPU STOP, PN cable cut, etc.). A dedicated 1-byte QI (Quality Information) word rides back to the controller, letting your interlock logic distinguish “real 0” from “module-offline substitute 0.” For pump/lube skids, this is what prevents a spurious “pump-off” trip during a PN watchdog miss.