Configuring SINAMICS G150 Master/Slave Without External PLC

Master/Slave Load Sharing on SINAMICS G150: Feasibility Overview

The SINAMICS G150 is a Siemens cabinet-format inverter engineered for single-motor variable-speed operation in the 75 kW to 2700 kW power band. Two product variants exist: the air-cooled G150 and the liquid-cooled G150 LC. Both are built on the SINAMICS S120 platform internally and use a CU320-2 Control Unit. The question of whether two G150 drives can be configured as a master/slave pair without an external PLC is therefore a question of how the SINAMICS drive objects can be interconnected rather than whether the hardware can do it.

The short answer: yes, two SINAMICS G150 drives can operate in a master/slave load-sharing topology with no PLC in the loop. The drive that you designate as master operates in closed-loop speed control; the drive you designate as slave operates in closed-loop torque control. The slave's torque setpoint is routed to it from the master's torque output. The routing can be implemented through three practical media: an analog voltage or current signal on the TM31 Terminal Module, a PROFINET or PROFIBUS cyclic process-data word via the CBE20 or onboard PROFIBUS interface, or — under specific hardware conditions — a SIMOLINK fiber-optic link.

The remainder of this article walks through the architecture, hardware, three workable topologies, the parameter map you need to set in STARTER or TIA Portal (Startdrive), the cement-kiln-specific considerations, a G150-versus-S120 comparison, and a commissioning verification procedure.

SINAMICS G150 Control Architecture Relevant to Master/Slave

The G150 inherits the SINAMICS drive object structure used by the S120. The salient objects for master/slave load sharing are:

• Control Unit CU320-2 – the central controller hosting the closed-loop control, free function blocks, and process-data routing. Two PROFINET ports (X150 P1, X150 P2) are present; onboard PROFIBUS is on X126.
• Line Module (Basic Line Module or Smart Line Module) – the rectifier section; not directly involved in master/slave logic.
• Motor Module – the inverter section that drives the motor; this is what carries the closed-loop control.
• TM31 Terminal Module – optional terminal expansion providing 8 digital inputs, 4 digital outputs, 2 analog inputs, 2 analog outputs, 1 temperature sensor input, and a reference voltage source. Mounted in the cabinet; standard on most G150 configurations.
• CBE20 Communication Board – optional PROFINET IRT / Ethernet/IP module installed at the CU320-2 option slot.

The drive firmware version (typically V5.x on older units and V6.x on current units) determines which parameters and which free function blocks are exposed. Always check the SINAMICS G150 firmware release notes in Siemens Industry Online Support for the exact parameter range of your firmware before commissioning. The parameters referenced below are stable across V5.2 SP3 and later, but defaults can differ.

The functional chain you are configuring is straightforward:

1. The master's speed setpoint enters the system from the plant PLC (or a local setpoint source).
2. The master's speed controller generates a torque demand as its output (r0791 / r1480).
3. The master's torque demand is transmitted to the slave through one of three media.
4. The slave's torque controller receives that torque demand and produces the motor current command.
5. Both motors share the mechanical load on the kiln pinion.

To make this work without a PLC handling the master torque broadcast, the SINAMICS free function blocks and BICO (Binector-Connector) routing are used on each drive.

Communication Hardware Options: CBE20, CU320-2 PROFINET, PROFIBUS, and TM31

Three hardware paths are practical. Each has different bandwidth, latency, determinism, and engineering effort.

The TM31 analog path is the simplest and is appropriate for slow-changing loads such as the rotary cement kiln described in the original application. The PROFINET path offers the best combination of bandwidth and engineering simplicity when a CBE20 is already fitted or specified. The SIMOLINK path is technically the best for very fast torque sharing but is rarely the right answer on G150 hardware because the SLB is not standard; verify availability against the G150 ordering data before committing.

Topology A: Master/Slave via Analog Torque Setpoint on TM31

The simplest implementation uses the master's TM31 analog output to broadcast a torque proportional voltage to the slave's TM31 analog input. Both drives must be set to the same torque reference scaling.

Wiring. The master's TM31 terminals X522 pin 12/13 (analog output 0, ±10 V) connect to the slave's TM31 X521 pin 3/4 (analog input 0, differential ±10 V). Use shielded twisted pair, ground the shield at one end only, and keep the run short — under 20 m if possible. For long runs, convert to 4–20 mA using a 500 Ω resistor at the slave input.

Master-side configuration (CU320-2 of master drive):

• p0771[0] = source connector for analog output 0 — connect this to r1480 (speed controller torque output, unsmoothed) or r0080[1] (torque actual value, smoothed) depending on whether you want the slave to share the master's commanded torque or the master's measured torque. For most load-sharing applications, the commanded torque (r1480) is the correct choice because it includes the speed-loop integral action.
• p0775[0], p0776[0], p0777[0], p0778[0] — set the analog output characteristic to a linear 0–100 % map. For a bipolar torque reference, configure the range to ±10 V with p0776 = -10 and p0777 = +10.
• p0779[0] = smoothing time constant (typically 5–20 ms to suppress noise on the analog line).

Slave-side configuration (CU320-2 of slave drive):

• p1300 = 22 — torque control without speed override (or p1300 = 23 if you want a speed-limiter fallback).
• p1503[0] = source connector for the torque setpoint — connect to the analog input scaling word r0755[0] (analog input 0 scaled value, normalized to ±100 % per the analog input characteristic).
• p1500[0] — set the torque setpoint source. For a pure analog-source torque follower, set this so p1503 is the active source. Typical value: p1500[0] = r0755[0] via BICO if the upstream source is analog; or use a free function block to forward it.
• p1501[0] — additional torque setpoint, set to zero (no offset).
• p1520, p1521 — upper and lower torque limits (in % of rated motor torque). These are critical: they prevent the slave from driving the kiln if the analog lead is broken. Set them to a value that bounds the slave to the expected torque share (e.g., 110 % of rated for transient overload tolerance).
• p1530, p1531 — power limit; same rationale.
• p2252, p2253 — if the slave uses a technology controller for torque limiting, configure the technology setpoint here. For pure torque control with analog input, this is typically not used.

This topology is recommended for kiln duty where the load-share accuracy requirement is ±5 % and the load changes slowly. Below that threshold and below 1 Hz torque variation, the analog path is acceptable.

Topology B: Master/Slave via PROFINET Cyclic Telegram (CBE20)

For higher fidelity load sharing, or when PROFINET is already part of the plant network, use a PROFIdrive cyclic telegram to broadcast the master's torque to the slave. The CBE20 option board adds two PROFINET IRT-capable ports to the CU320-2 of each G150.

Telegram selection. The PROFIdrive standard telegrams 1–6 are available; for master/slave load sharing, free configuration (telegram 999) or telegram 6 (speed setpoint 32-bit with torque limit and torque actual value) is most useful. Configure both drives with the same telegram type so the interconnect mapping is direct.

Set the telegram on each drive:

• p0922 = 999 (free configuration) — or a standard telegram such as p0922 = 6 if torque is already part of the standard telegram.
• When using telegram 999, configure the receive and send words manually via p2050/p2051 (receive) and p2080/p2081 (send).

Master transmit side.

• p2051[0] = the connector that supplies word 1 of the send telegram. Set to r0080[1] (torque actual value, smoothed) — represented as a normalized 16-bit value where 100 % rated torque = 4000 hex (16384 decimal). Optionally include r0079 (torque setpoint total) as word 2.
• p2051[1] = r0079 if a second word is needed.

Slave receive side.

• p2050[0] = the connector input that receives word 1 of the receive telegram. SINAMICS automatically scales the PROFIdrive-normalized torque value (4000 hex = 100 %) and exposes it on the connector. Connect p1503[0] = r2050[0] in modern firmware; in older firmware you may need a free function block in between. Verify with the SINAMICS function diagram 8030 in the parameter manual for your firmware.
• p1300 = 22 for torque control.

PROFINET configuration. The two drives appear on PROFINET as separate IO Devices. The exchange is unidirectional from master to slave. Configure the controller on a third device (the plant PLC) for the IO Device name assignment and topology discovery, then write the master's torque word to the slave's input mapping. Although this still uses a PLC at commissioning time to set device names and IP addresses, at runtime no PLC is in the loop: PROFINET IRT operates as a time-scheduled cyclic exchange directly between the IO Devices after the PLC has completed the start-up phase.

PROFIBUS alternative. If the network is PROFIBUS rather than PROFINET, the same parameter structure applies. Use p0922 = 999 on the CU320-2 onboard PROFIBUS X126. DP-V2 isochronous mode (p0015 = 6 or via PROFIBUS master configuration) gives cycle-locked behavior; otherwise, DP-V1 with default 1–4 ms cycle is adequate for kiln load sharing.

Topology C: SIMOLINK on G150 — Hardware Caveats

SIMOLINK is a Siemens-proprietary fiber-optic ring protocol that provides synchronous, deterministic drive-to-drive communication at a 3.2 µs node transit time. It is the preferred medium for S120 multi-axis master/slave load sharing and for S120 Active Line Module paralleling. On G150 it is not a standard fit; the SLB (SIMOLINK Board) option is generally only available on S120 multi-axis configurations.

Before specifying SIMOLINK on a G150 retrofit:

1. Confirm that the G150 was ordered with the SIMOLINK option code (the option identifier in the G150 MLFB will reflect this — refer to the G150 ordering documentation).
2. If the option is present, the SLB occupies one of the CU320-2 option slots and the fiber-optic ports are accessible from the cabinet front.
3. If the option is absent, you cannot use SIMOLINK on a G150 — use the CBE20 PROFINET or PROFIBUS path instead.

Configuration when present: SIMOLINK on SINAMICS uses telegram types selected via p0015 or via the SLB-specific configuration pages in STARTER / Startdrive. The torque setpoint from the master drive is routed via SIMOLINK channel configuration. Refer to the SIMOLINK function manual on Siemens Industry Online Support for the exact channel tables and the firmware-version dependency.

STARTER and TIA Portal (Startdrive) Configuration Parameters

Configure both drives using either STARTER (legacy) or TIA Portal with Startdrive (current). The parameter set is identical because both tools communicate to the drive via PROFIdrive parameter access.

Step-by-step commissioning flow:

1. Connect to the master drive (default PROFINET IP 192.168.0.10 / PROFIBUS address 3) via STARTER / Startdrive over Ethernet or PROFIBUS.
2. Open the project, perform an Online → Load to PG of the drive topology. Verify the drive object list (DO1 = Control Unit, DO2 = Motor Module, optionally DO3 = TM31).
3. Run the basic commissioning wizard for the motor (motor code, motor data, encoder if present, motor identification). Save the parameters.
4. Set p0003 = 3 (expert access) to expose all expert parameters.
5. Configure master control mode: p1300 = 21 (speed control with torque limit) — the standard master mode for a load-sharing application.
6. Configure the torque broadcast per Topology A, B, or C above.
7. Save parameters: p0971 = 1 (save RAM to ROM).
8. Repeat steps 1–7 for the slave drive, using slave control mode p1300 = 22 (torque control).
9. Configure IP / device name / PROFIBUS address so the master and slave are addressable.
10. Run the basic commissioning and identification on the slave.

Parameter map summary (firmware-version-independent core set):

Confirm exact defaults and parameter limits against the firmware-specific parameter manual for your SINAMICS version. The SINAMICS G150 product page links to the current operating instructions and parameter manual.

Cement Kiln Application Specifics

For a rotary cement kiln, two-motor drives are common on large kilns where a single motor does not have sufficient torque. Both motors drive the same pinion through a shared gearbox, or each motor drives its own pinion with both pinions meshing with the kiln girth gear. The load-sharing requirement is typically within ±5 % to ensure even wear on the pinions and to avoid asymmetric loading on the kiln shell.

Mechanical constraints:

• Both motors see the same speed reference (kiln rotational speed in the range 0.5–5 rpm at the kiln shell, after gearbox reduction).
• Mechanical coupling is rigid; torque differences translate directly into pinion tooth loading and gearbox bearing load.
• During clinker build-up or refractory upset, the load can change rapidly; a higher-bandwidth torque sharing path is preferable in these conditions.

Recommended drive topology for kiln duty:

1. Preferred: S120 multi-axis with SIMOLINK or PROFINET IRT between the master and slave Motor Modules. S120 is the natural choice for this application because it is multi-axis by design.
2. Acceptable: Two G150 drives with PROFINET IRT (CBE20) and the master/slave configuration described in Topology B above. Bandwidth is sufficient for kiln duty.
3. Acceptable but lower fidelity: Two G150 drives with the TM31 analog path (Topology A). Adequate for steady-state load sharing but slow to respond to upsets.

Mechanical protection. Even with a master/slave scheme, fit a torsionally flexible coupling or hydraulic coupling between the two motors if the mechanical layout permits. This prevents torque-fighting during transient communication dropouts. If a rigid connection is unavoidable, configure the torque limit p1521 on the slave to clamp the maximum reverse torque it can apply (e.g., 10–15 % of rated) so that a torque sign error in the broadcast cannot drive the two motors against each other.

Master and slave motor selection. Use matched motors of the same rating, same speed constant, same encoder type. Differences in motor characteristics will degrade load-sharing accuracy regardless of how good the torque broadcast is.

G150 vs SINAMICS S120 for Load-Sharing Applications

The G150 is technically capable of master/slave, but the S120 is purpose-built for it. The selection decision depends on whether you are designing a new installation or retrofitting an existing one.

Decision path:

• Greenfield design for a kiln with two drive motors: choose S120 multi-axis. The engineering investment pays back in commissioning time, load-sharing fidelity, and lifecycle support.
• Brownfield retrofit on existing G150 equipment: stay with G150. The retrofit cost of replacing G150 with S120 would not be recovered.
• Single-motor kiln with future expansion possibility: stay with G150. Add the CBE20 option at order time to enable later expansion to a two-drive configuration without hardware rework.

If you choose to migrate from G150 to S120 for the master/slave function, the migration is not a drop-in replacement. S120 requires a different cabinet layout, different Line Module sizing, and different commissioning workflow. Reference the Siemens Industry Online Support SINAMICS migration documentation for the specific motor-module and line-module selection process.

Commissioning Verification, Diagnostics, and Fault Handling

Commission the master and slave drives one at a time, then together.

Stage 1 — Master alone:

1. Run the motor identification on the master motor with the load disconnected.
2. Verify speed control is stable across the speed range of the kiln (typically 0–110 % of rated speed).
3. Verify the torque broadcast output is present on the analog output or PROFINET send word. Use STARTER / Startdrive online trace or an oscilloscope on the analog output to confirm.

Stage 2 — Slave alone:

1. Run motor identification on the slave motor with the load disconnected.
2. Apply a manual torque setpoint from STARTER (write to p1503 directly) and verify the slave motor produces torque proportional to the setpoint.
3. Verify torque limits p1520 / p1521 are clamping correctly.

Stage 3 — Both drives together with mechanical coupling:

1. Enable the master with the slave in torque-control standby (enable the slave with no torque setpoint).
2. Slowly ramp the kiln speed. Observe master actual torque r0080[1] and slave actual torque r0080[1] in STARTER online trace. Verify both drives share the load within ±5 %.
3. Run a load step test: apply a known mechanical disturbance (e.g., a brief reduction in feed rate or an artificial loading using the process) and verify the master torque controller compensates and the slave follows.
4. Verify the communication path by disconnecting the broadcast and verifying the slave safely faults or limits to zero torque on loss of setpoint.

Fault handling — common faults to expect:

Setpoint tracing. Use the STARTER or Startdrive trace function to record the master torque (r0080[1]), the broadcast value (r0755[0] or PROFIdrive send word), and the slave torque actual value (r0080[1]) simultaneously. Trigger the trace on a load step and verify the slave tracks the master within one or two speed-controller cycle times.

Save and back up. After commissioning, save parameters on both drives with p0971 = 1 and upload the parameter sets via STARTER / Startdrive to the project archive. This is the only way to recover the master/slave configuration if a drive needs replacement.

Frequently Asked Questions