SINAMICS G120 Startup & Configuration Guide (PM240-2 + CU240E-2)

Bringing a Siemens SINAMICS G120 inverter from the shipping crate to a running motor takes about 30 minutes when the steps are clear and roughly half a day when they're not. The drive is modular — a Power Module (commonly PM240-2 in the G120 family) docks with a Control Unit (CU240B-2 or CU240E-2), a BOP-2 keypad or IOP intelligent panel attaches to the front, and parameters live in the Control Unit's memory card. Each piece has its own commissioning step, and missing one is the usual reason a drive sits faulted on the bench.

This guide is written for maintenance engineers, panel builders, and integrators commissioning G120 with PM240-2 power modules and CU240E-2 control units. It walks the canonical Siemens path: hardware wiring, BOP-2 navigation, the parameter-filtered Quick Commissioning sequence (P0010 = 1), motor data identification (P1900), control mode selection between V/f and sensorless vector (P1300), and the most common fault codes you'll meet on first power-up. Parameter numbers and fault codes below come from the SINAMICS G120 List Manual for CU240B-2 / CU240E-2.

Quick-reference table: G120 commissioning at a glance

Step 1 — Wiring PM240-2 plus CU240E-2

Power-side terminations

On the PM240-2:

• L1, L2, L3 — three-phase supply input (380–480 V class for the most common North American frames). Frame Sizes A and B are also offered in single-phase 200–240 V; check the order code (the third group identifies voltage class).
• U2, V2, W2 — motor output. Three-phase only.
• DCP / R1, R2 — DC bus and external braking resistor on frames that support one. PM240-2 has the brake chopper built in; only the resistor needs to be wired externally.
• PE — protective earth, separate stud on the PM240-2 chassis. Use both the line-side and motor-side PE points; do not chain them.

For long motor cable runs (above 50 m unshielded or 100 m shielded), fit an output reactor or dV/dt filter to suppress reflected-wave overvoltage at the motor terminals — the cause of most early motor insulation failures on G120 installations. Use symmetrical shielded VFD cable, terminated with a 360° EMC clamp at both ends.

Control-side wiring on CU240E-2

The CU240E-2 (PN, DP, or non-fieldbus variants) carries the I/O terminals and the safety inputs:

• DI 0–5 — six digital inputs, default sources for ON/OFF1, reverse, and acknowledge depending on the macro you pick.
• DI 16, DI 17 — STO (Safe Torque Off) inputs. Both must be at +24 V for the inverter to enable. If safety isn't being used, jumper to the +24 V source per the installation manual; the drive will not run with floating STO terminals.
• AI 0, AI 1 — two analog inputs, jumper-selectable for 0–10 V or 4–20 mA via the dual-row pin block on the CU240E-2.
• DO 0, DO 1, DO 2 — relay outputs (NO/NC/COM), default mapping varies by macro.
• +24 V, 0 V — internal 24 V supply for sourcing DIs, current-limited per the installation manual.

If the drive is networked, complete the fieldbus connection (PROFINET RJ45 ports on CU240E-2 PN, PROFIBUS sub-D on the DP variant) before powering up — the device name and IP/MAC behavior depend on what's set during the first boot.

Step 2 — First power-up and BOP-2 navigation

On first power-up after a fresh-from-Siemens installation, the inverter performs internal initialization for 10–30 seconds. The BOP-2 panel shows:

• MENU screen with MONITOR, CONTROL, DIAGNOS, PARAMS, SETUP, EXTRAS
• Status icons for ready, running, faulted, and command source

BOP-2 keys you'll use constantly:

• OK — accept value or enter parameter
• ESC — back out without saving
• M (menu) — switch between menu trees
• Up / Down — change parameter index or value digit
• FN — function key, used as digit-shift in long parameter values
• HAND/AUTO — only on IOP variants; toggle command source

To check that you have the right hardware and firmware before commissioning:

• r0018 — firmware version of the Control Unit
• r0964 — drive identification (manufacturer ID and version)
• r0200 — Power Module code number (compare with the PM240-2 label)

If r0200 = 0, the Control Unit is not seeing the Power Module — usually a seating problem on the PM-CU interface or a damaged ribbon connector.

Step 3 — Quick Commissioning (P0010 = 1)

Setting P0010 = 1 filters the parameter list down to commissioning-relevant items only and starts the Quick Commissioning sequence. Until you exit by setting P3900, the drive will not run — this is by design, so you can't accidentally start a motor with half-configured data.

P0010 values you'll encounter:

• P0010 = 0 — Ready (normal operating state)
• P0010 = 1 — Quick Commissioning
• P0010 = 2 — Power Module commissioning
• P0010 = 3 — Motor commissioning
• P0010 = 5 — Technological application commissioning
• P0010 = 30 — Parameter reset (set with P0970 = 1 to factory-default)

From the BOP-2: SETUP → BASIC SET → enter the wizard. Or PARAMS → PR FILT → set EXPERT, then access P0010 directly.

Step 4 — Application macro (P0015) and command sources

Rather than wiring every digital input by hand, the G120 ships with pre-built application macros. P0015 picks one. Common values for CU240E-2:

• P0015 = 1 — Conveyor with two fixed speeds (DI0 = ON, DI1 = reverse, DI4/5 = fixed setpoints)
• P0015 = 7 — PROFINET / PROFIBUS process data control (telegram 1)
• P0015 = 12 — Standard I/O with analog setpoint (DI0 = ON, AI0 = setpoint)
• P0015 = 17 — 2-wire control with two analog setpoints
• P0015 = 21 — Fieldbus with data set switchover

If none of the macros fit the application exactly, pick the closest, then customize the BICO connections via P0840 (ON/OFF1 source), P1000 (setpoint source), and the digital input function parameters P0701–P0706. Macros are not a one-way trip; you can reapply or modify after the fact.

Step 5 — Motor nameplate data

This is the step that decides whether the rest of the commissioning goes smoothly or fights you for hours. Enter the values exactly as printed on the motor nameplate, in the units the nameplate uses, then verify the math.

P0100 selects the units system: 0 = kW / 50 Hz, 1 = hp / 60 Hz, 2 = kW / 60 Hz. Set this before entering rated power; otherwise hp values get interpreted as kW and the motor model goes wrong.

For star/delta selection on dual-rated motors: enter the values for the connection actually wired in the junction box. A 230/460 V motor wired in star on a 460 V supply uses the 460 V column.

Step 6 — Control mode (P1300)

P1300 picks how the inverter regulates the motor. The choice influences torque response, low-speed behavior, and which subsequent parameters become relevant.

• P1300 = 0 — V/f linear (factory default). Simplest, lowest torque at zero speed, fine for fans and pumps.
• P1300 = 1 — V/f linear with FCC (Flux Current Control), better low-speed torque than pure V/f.
• P1300 = 2 — V/f parabolic (squared). For variable-torque loads (centrifugal pumps and fans) where energy savings matter.
• P1300 = 3 — V/f programmable. Custom curve via P1320–P1327.
• P1300 = 5 — V/f for textile applications (precise frequency).
• P1300 = 19 — V/f with independent voltage setpoint.
• P1300 = 20 — Sensorless vector control. Strong torque from low speed, requires accurate motor data and a successful P1900 identification.
• P1300 = 22 — Vector with encoder feedback (requires encoder option on supported CU variants).

Field rule of thumb: choose P1300 = 2 for fans/pumps you want to save energy on, P1300 = 0 when you can't afford to mis-tune (constant-torque conveyors with intermittent service), and P1300 = 20 when you need full torque from low speed (extruders, mixers, hoists with mechanical brakes).

Step 7 — Ramps and frequency limits

• P1080 — minimum frequency (default 0 Hz). Set above 0 if the application needs guaranteed cooling on the motor at minimum speed.
• P1082 — maximum frequency (default 50 Hz). For 60 Hz motors set to 60; for over-speed applications set above rated and confirm motor mechanical limit.
• P1120 — ramp-up time from zero to P1082 in seconds. Default 10 s.
• P1121 — ramp-down time. Default 10 s. If you see F30002 (DC link overvoltage) on stop, lengthen P1121 or fit a brake resistor.
• P1130 / P1131 — initial / final ramp rounding (S-curve smoothing).

Step 8 — End Quick Commissioning (P3900)

P3900 closes Quick Commissioning and triggers internal motor calculations:

• P3900 = 1 — End with motor data calculation and reset to factory for non-touched parameters. Most thorough.
• P3900 = 2 — End with motor data calculation only.
• P3900 = 3 — End with motor data calculation, limited (PM-only).

The drive runs for several seconds calculating equivalent-circuit parameters, then sets P0010 back to 0. You're now ready for motor identification.

Step 9 — Motor data identification (P1900)

Quick Commissioning gets the inverter into the right ballpark from nameplate data; P1900 measures the actual motor at standstill (or with rotation) to refine stator resistance, leakage inductance, and magnetizing curve. Skipping it is the most common cause of poor torque response and nuisance F30001 (overcurrent) trips on vector mode.

• P1900 = 0 — disabled (default after P3900).
• P1900 = 2 — measurement at standstill. Motor must be uncoupled or coupled to a low-friction load. Drive injects DC to measure stator R and leakage, then small AC pulses for magnetizing curve.
• P1900 = 3 — measurement with rotation. Drive spins the motor to characterize saturation. Requires the load be uncoupled.

After setting P1900 = 2 or 3, the BOP-2 displays alarm A07991 ("identification active, switch on motor"). Within 20 seconds, issue an ON command (DI0 in default macros, or HAND on IOP). The drive then runs the identification sequence automatically and stops. If you don't issue the ON command in time, P1900 reverts to 0 and you'll need to re-arm.

When identification completes successfully, the alarm clears and the measured values appear in r1912 (stator resistance), r1913 (rotor resistance), r1925 (saturation curve), among others.

Step 10 — Save and test run

Set P0971 = 1 to copy the RAM parameter set to ROM. On drives with a memory card fitted, also use P0804 = 1 to write the configuration to the card — this is your portable backup, and it's how you'll restore the same configuration to a replacement Control Unit without re-commissioning.

For a first test run from BOP-2: HAND mode → ON. Watch:

• r0021 — actual frequency
• r0027 — actual current (compare against P0305 rated)
• r0026 — DC link voltage (typical 540–650 V on 480 V class)
• r0028 — actual output voltage

If the motor turns the wrong way, cycle off and swap any two of U2/V2/W2 — do not change P1101 or other phase-rotation parameters at this stage; physical swap is cleaner and avoids confusion later when someone else services the panel.

Common faults and alarms during startup

For each fault code, the BOP-2 path is: DIAGNOS → FAULTS to read the code, then DIAGNOS → FLT-LST for the history of the last 8. Use P0952 to read the count and P0945[0..7] for the codes; P0948[0..7] gives time stamps in milliseconds since power-on.

Wiring and parameter cheat sheet

• STO inputs (DI 16, DI 17) — both must see +24 V or the drive shows F07802 / no enable. Jumper to +24 V if safety unused.
• P0010 sequence — set 1 to enter, 30 + P0970 = 1 to factory-reset, 0 to operate.
• P0100 — set kW/hp first, before P0307.
• P0335 — must be 1 (forced cooling) for force-cooled motors, otherwise F07011 nuisance trips at moderate load.
• P1900 = 2 — always run after first commissioning; rerun if you change motor or significantly change cable length.
• P0971 = 1 — saves to non-volatile memory. Without this, parameters are lost on power-down.
• P0804 = 1 — saves to memory card. Critical for fast Control Unit replacement.

Decision tree: when startup faults point to hardware

• Repeat F30001 with motor data verified, P1900 done, ramps relaxed — output stage or current sensor on Power Module suspect; consider PM240-2 replacement.
• F30021 (ground fault) with motor disconnected — internal ground fault in the inverter; replace.
• F30027 on every power-up — pre-charge resistor or contactor in PM240-2 has failed.
• F07802 with STO confirmed energized and CU LED green — internal hardware not signaling ready; reseat CU on PM, check for r0200 = 0 (PM not detected). If reseating fails, the PM-CU interface is the culprit.
• F30004 / F30024 with cooling intact and load below rating — heatsink thermistor or fan-control circuit; PM service or replacement.
• BOP-2 dead but PM LEDs normal — CU or BOP-2 fault; swap BOP-2 first (cheaper test).

When the diagnosis points at replacement, source the CU and PM by exact order code from the device label. CU240E-2 PN (6SL3244-0BB13-1FA0) is not interchangeable with CU240E-2 PN-F (which adds Safety Integrated Extended Functions); PM240-2 frame size and voltage class must match the original. Browse our in-stock SINAMICS drive components and accessories, and pair with a compatible Siemens S7 PLC for retrofit projects where you're consolidating an older legacy line. For cross-references between SINAMICS generations or upgrades from MICROMASTER 4, our team can map your existing order code to a current-production equivalent.

Preventive practices

• Back up commissioning — use P0804 to write the config to the memory card and store the card with the panel documentation. Replacing a CU without a card backup means re-commissioning from scratch.
• Document P0015 macro and any custom BICO connections — if you've modified DI/DO mapping, future maintenance will need that record.
• Periodically review fault history — P0945 plus P0948 timestamps reveal slow trends (rising F30004 frequency means cooling is degrading).
• Verify P1900 has been run — on a drive someone else commissioned, check r1912 and r1925; if they show default values, identification was skipped and vector performance will be poor.
• Update firmware deliberately — Siemens releases firmware updates with parameter changes; never update on a running site without a config backup and a planned downtime window.

FAQ

Why can't I exit Quick Commissioning with P0010 = 0?

P0010 = 0 by itself doesn't run the motor-data calculation. Set P3900 = 1 (or 2) instead — the drive will calculate equivalent-circuit values and then automatically return P0010 to 0. If you set P0010 = 0 directly without P3900, the inverter returns to ready state but the motor model is still default and you'll see poor torque or F30001 trips.

The drive shows A07991 and won't run. What did I miss?

A07991 means motor identification is armed and waiting for an ON command. From the default macro, that's DI0 high (digital input 0). Press HAND on the IOP, or activate DI0 wiring from the panel button. You have 20 seconds; after that, P1900 reverts to 0 and you'll see no fault but no run either. Re-set P1900 = 2 and try again.

What's the difference between V/f (P1300 = 0) and sensorless vector (P1300 = 20)?

V/f maintains a fixed voltage-to-frequency ratio and runs open-loop. Simple, robust, low torque near zero speed. Sensorless vector estimates rotor flux from current and voltage measurements, giving 100% torque from a few Hz upward. Vector requires accurate motor data and a successful P1900 identification; on a poorly tuned motor, vector mode can be more troublesome than V/f. Start with V/f, switch to vector when the application clearly needs the low-speed torque.

Do I need to run P1900 on every commissioning?

Yes for vector mode (P1300 = 20 or higher). For V/f modes the inverter can run acceptably from nameplate values alone, but motor identification still improves slip compensation and current measurement accuracy. Five extra minutes of identification at commissioning prevents hours of nuisance trip troubleshooting later.

How do I copy a known-good configuration from one G120 to another?

On the source drive, set P0804 = 1 to write the parameter set to the memory card. Power down, transfer the card to the target drive, power up. The target drive auto-detects the new card; on first power-up it copies the card contents to internal memory if you've configured it to (or use P0802 = 2 to force a card-to-drive copy). The motor will need to be the same model, or you'll need to re-enter motor data and rerun P1900 on the target.

Need replacement SINAMICS hardware or commissioning support? Browse our in-stock SINAMICS G120 power modules, control units, and operator panels, or pair with a compatible Siemens S7-1500 PLC for new-build automation projects. We cross-reference legacy MICROMASTER 4 order codes to current G120 equivalents for retrofit work.