Product Overview
The 6ES7132-6GD51-0BA0 is a Siemens SIMATIC ET 200SP signal relay module, type-designated RQ CO 4×24 V DC/2 A ST—four relay changeover (SPDT, 1 NO + 1 NC) outputs, each with an isolated dry contact rated 2 A, driven by a 24 V DC coil supplied from the ET 200SP inherent 24 V rail. It belongs to the “ST” (Standard) performance class of the ET 200SP digital output family and slots into the ultra-compact ET 200SP distributed I/O head station that hangs off a PROFINET IO controller—commonly an S7-1500 CPU, but also usable behind an S7-1200/300/400 with IM 155-6 PN HF or behind a third-party PROFINET controller via GSDML. At 15 mm width (the signature ET 200SP “finger-width” form factor), the 6ES7132-6GD51-0BA0 packs four fully isolated relay channels into a footprint that would barely hold one channel on legacy ET 200S or S7-300 SM 322 relay cards, making it the default choice for MCC-contactor-coil, solenoid, and small-motor auxiliary loops on remote skids where cabinet real estate is precious.
The module seats onto a BU-type A0 BaseUnit (the ET 200SP “backplane” that carries field wiring via push-in terminals—no separate front connector as on S7-300 SM modules), and is mechanically keyed by Color Code CC00 so a maintenance tech can’t accidentally seat a different I/O type on a BaseUnit whose wiring expects relay outputs. Firmware is static (V0.0, no updates) because the relay driver is pure hardware; configuration happens in TIA Portal V14+ or STEP 7 V5.5 SP3+, with PROFINET GSDML V2.3 and PROFIBUS GSD Rev 3/5 available for non-Siemens controllers. The 6ES7132-6GD51-0BA0 supports I&M0 through I&M3 (Identification & Maintenance) data, substitute-value output on loss of PROFINET communication, and module diagnostics focused on 24 V coil-supply voltage monitoring—green PWR LED for supply, green-per-channel status LEDs, and a green/red DIAG LED for module-level events.
Physically the module is 15 × 73 × 58 mm, ≈ 30–38 g, and rated 0 … +50 °C horizontal (derated to +60 °C at reduced total current). Isolation is 707 V DC type-tested between channels, between channels and backplane, and between channels and electronic-supply—critical because relay dry contacts let the 6ES7132-6GD51-0BA0 switch loads that are themselves 24 V DC, 230 V AC, or mixed potentials, all while the ET 200SP backplane talks PROFINET at 24 V logic levels.
Technical Specifications
| Parameter | Value |
|---|---|
| Product Model | 6ES7132-6GD51-0BA0 |
| Manufacturer | Siemens |
| Product Type | SIMATIC ET 200SP Signal Relay Module (DQ), RQ CO 4×24 V DC/2 A ST |
| Number of Outputs | 4, relay changeover (SPDT, 1 NO + 1 NC) |
| Coil Supply Voltage | 24 V DC (range 19.2–28.8 V), reverse-polarity protected |
| Current Consumption (coil all on) | 50 mA (module) + 40 mA (4× relay coil) |
| Power Loss (typ.) | 1.2 W |
| Contact Rating (resistive) | 2 A max/channel, 8 A max/module (horiz. ≤40 °C) |
| Thermal Continuous Current | 2 A per contact |
| Switching Voltage | 24 V DC / 24 V AC rated (dry contact, application-limited by isolation) |
| Min. Switching Current | 1 mA @ 5 V DC |
| Mechanical Operating Cycles | 500 000 max |
| Switching Frequency (resistive load) | ≤ 2 Hz max |
| Parallel Switching | 2 outputs allowed (for redundant load control, not uprating) |
| Short-Circuit Protection | No (relay contact side) |
| Isolation (type test) | 707 V DC — ch↔ch, ch↔backplane, ch↔elec. supply |
| Cable Length | 1 000 m shielded / 200 m unshielded |
| Address Space | 1 byte outputs + 1 byte QI (quality info) |
| Fitting BaseUnit | BU-type A0 |
| Color Code | CC00 |
| Diagnostics | Supply-voltage monitoring, substitute value, diagnostic alarm |
| Dimensions (W×H×D) | 15 × 73 × 58 mm |
| Weight | ≈ 30–38 g |
| Operating Temp | 0 … +50 °C (horiz.), +60 °C derated; vert. mount lower |
| Protection | IP20 |
| Approvals | CE, cULus, etc. (standard Siemens ET 200SP portfolio) |
Main Features and Advantages
Ultra-narrow 15 mm with four isolated changeover contacts. The standout of the 6ES7132-6GD51-0BA0 is packing 4× SPDT relay outputs into 15 mm of DIN width—less than one-third the width of an S7-300 SM 322 8×relay (40 mm for 4 channels equivalent). In an ET 200SP head station limited to, say, 12 modules per IM 155-6 PN HF, that width economy lets the rack mix relay DO, transistor DO, AI, AO, and DI in high density without jumping to a second IM. Each channel is a true changeover (COM + NO + NC), so one 6ES7132-6GD51-0BA0 channel can simultaneously drive a “Run” contactor coil (NO) and feed a “Fault–Motor Not Running” annunciator (NC)—something a pure NO transistor DO can’t do without external interposing relays.
Dry-contact isolation across channels and to backplane. Unlike transistor DO modules (6ES7132-6BFxx) that share a common 24 V / 0 V rail per group, the 6ES7132-6GD51-0BA0 has 707 V DC type-tested isolation channel-to-channel and channel-to-backplane. This means Ch0 can switch a 24 V DC contactor coil grounded to Panel A, Ch1 can switch a 120 V AC solenoid grounded to Panel B, and Ch2 can switch a 230 V AC horn on a third earth—all on the same 6ES7132-6GD51-0BA0 without channel-crosstalk or backplane pollution. For retrofit skids where field-device earthing isn’t uniform, this isolation is the reason to pay the relay premium over a transistor DO.
BU A0 seating with CC00 color coding. The 6ES7132-6GD51-0BA0 doesn’t use a removable front connector (the legacy S7-300 pain point where a tech swaps a module and forgets to move the connector). Instead it clicks onto a BU-type A0 BaseUnit whose push-in terminals hold the field wires (4× COM+NO+NC = 12 terminals per module, plus BU A0’s own potential bridges). The CC00 color ID plate on the module must match the BU’s color tab—if someone tries to seat a different I/O type (say a 6ES7131 DI by mistake) on a relay-wired BU, the color won’t match and the mechanical key prevents seating. This “zero-wrong-plugin” design matters on outage nights when sleep-deprived electricians are swapping spares.
Substitute-value output and diagnostics. The 6ES7132-6GD51-0BA0 supports substitute-value (Ersatzwert) configuration in TIA Portal: if PROFINET IO drops (controller stops, cable cut, IM 155-6 reboots), each relay channel can be pre-programmed to “stay as-is,” “go OFF,” or “go ON” instead of flapping. For a pump-contactor loop this prevents an uncontrolled restart on comms recovery; for a fire-pump latch it might force ON. The module also pushes a diagnostic alarm on 24 V coil-supply loss (PWR LED goes out, DIAG red), so the control room knows “ET 200SP rack A’s 24 V bus dropped—relay module A3 lost coil power” before wondering why contactors didn’t pick up.