SIEMENS SINAMICS S120 Servo Drive System Application Guide

SIEMENS SINAMICS S120 Servo Drive System Application Guide: Complete Technical Analysis from Configuration to Optimization

In the field of modern industrial automation, motion control and servo drive technology are the core of achieving precision mechanical motion. The Siemens SINAMICS S120 series drive, as a high-performance representative of the Siemens drive family, occupies an important position in single axis and multi axis drive applications with its modular design, high-precision control, and powerful functional integration. This article aims to systematically introduce the composition architecture, project configuration process, basic debugging methods, motor optimization strategies, basic positioning functions, and communication implementation methods of the SINAMICS S120 drive system, providing a comprehensive and professional technical reference for drive system engineers.

Overview of SINAMICS S120 Drive System

SINAMICS S120 is a multi axis drive system that integrates V/F control, vector control, and servo control, capable of meeting the increasing number of axes and high-performance control requirements in industrial applications. According to different application scenarios, the S120 driving system is mainly divided into two structural forms: single axis AC/AC driver and multi axis DC/AC driver.

1.1 AC/AC Single Axis Drive

AC/AC single axis drive integrates the power module and motor module into one, commonly known as SINAMICS S120 single axis AC drive. It can achieve high-precision control of ordinary three-phase asynchronous motors, asynchronous servo motors, synchronous servo motors, torque motors, and linear motors. The core components of this driver include a control unit (CU310 DP or CU310 PN) and a power module (PM340). The control unit is connected to the power module through the PM-IF interface, and all DRIVE CLiQ components exchange high-speed data through a dedicated interface. Users can use the basic operation panel BOP20 for parameter settings and diagnostics.

1.2 DC/AC Multi Axis Drivers

The DC/AC multi axis drive adopts a common DC bus structure, which separates the power module from the motor module. The power module rectifies three-phase AC power into 540V or 600V DC power, and multiple motor modules share this DC bus. This structure is particularly suitable for multi axis control systems in industries such as papermaking, packaging, textiles, printing, and steel. Its advantage is that energy sharing can be achieved between each axis, and the wiring is simple and easy to expand.

The core control unit of the SINAMICS S120 multi axis drive system is CU320, which can control up to 6 servo axes or 4 vector axes in speed control mode. The main components of the system include:

Control unit (CU320): responsible for controlling and coordinating all modules, completing closed-loop control of current loop, speed loop, and position loop.

Power module: divided into basic type (BLM, no feedback function), intelligent type (SLM, rectification feedback unit), and active type (ALM, adjustable DC bus voltage).

Motor module: also known as inverter unit, divided into single axis and dual axis modules.

Sensor module: Convert encoder signals into signals recognizable by DRIVE CLiQ.

24V DC power module: supplies power to the system control part.

All modules are interconnected through a high-speed drive interface DRIVE CLiQ, forming a highly integrated modular system.

1.3 System status indication

Each module of SINAMICS S120 is equipped with LED indicator lights to reflect the real-time operation status of the equipment. For example, if the RDY indicator light of control unit CU320 is constantly green, it indicates that the module operation is ready and DRIVE CLiQ communication is normal; The constant red light indicates the presence of a fault; The constant orange light indicates that DRIVE CLiQ communication has been established. The READY and DC LINK indicator lights of the power module and motor module also provide critical operating status and fault information for quick on-site diagnosis.

Project configuration: offline and online modes

The debugging of SINAMICS S120 is completed by creating a project, which can be done in two ways: offline configuration and online configuration. Regardless of the method used, the prerequisite preparation work includes: preparing a PC with SCOUT software installed, connecting the hardware, and setting the DP address.

2.1 Offline Project Configuration

Offline configuration is suitable for Siemens standard motors or third-party motors without DRIVE CLiQ interface. All project data is manually entered offline and downloaded to the driver device after configuration is complete. The specific steps are as follows:

Create a new project: Create a new project in SCOUT software, set the project name and storage path.

Set DP communication port: Set the communication port through Set PG/PC Interface and configure the baud rate (default is 1.5Mbps or 12Mbps). Use the Diagnostics function to test whether the DP card is working properly and read the station numbers of all workstations to ensure that the programmer can access the driver device.

Configure the driver unit: Based on the actual hardware, sequentially configure the power module (SLM or ALM), motor module, encoder, and motor. For servo motors (such as 1FK7 series), the motor model needs to be selected from the list; For vector motors (such as 1PH7 or 1LA7 series), manual input of nameplate parameters (rated voltage, current, power, frequency, speed, etc.) is required. After the configuration is completed, the system generates a project summary for users to review.

Download and Storage: Connect the target device online and execute "Load project to target device" to download the project to the RAM of S120. To prevent data loss, it is necessary to perform "Copy RAM to ROM" to save the parameters to the CF card. Finally, execute 'Load to PG' to upload the project to the programmer and save it.

2.2 Online Project Configuration

Online configuration is suitable for Siemens motors with DRIVE CLiQ interface. The system automatically recognizes and reads data from each module and motor through DRIVE CLiQ, without the need for manual input. The process is as follows:

Create a project and set up DP communication port: the same as the first two steps of offline configuration.

Insert driver: Select the device type (such as SINAMICS S120 CU320) and device version, and set the bus address consistent with the hardware.

Online connection and factory restoration settings: Click on "connect to target system" to establish a connection, and then execute "Restore factory settings" to restore the device to its factory state.

Automatic configuration: Double click "Automatic configuration", and the system will automatically recognize all components with DRIVE CLiQ interface. For components without DRIVE CLiQ interface (such as encoders connected through SMC modules), the system will prompt the user to perform offline manual configuration.

Manual supplementary configuration: Disconnect the online connection, find the unrecognized component in the project navigation bar, and manually complete the configuration (refer to the offline configuration steps).

Download and Storage: Connect online again, perform download, Copy RAM to ROM, and save operations to complete project creation.

Basic debugging methods and tools

After completing the project configuration, S120 can be debugged in various ways.

3.1 Control panel controls motor

The Control Panel function in SCOUT software is the most direct debugging tool. When operating, first select the axis to be controlled, click "Assume control priority" to obtain control, then enable the driver, set the speed, and finally click the green button to start the motor. Users can adjust the motor operating speed between 0% and 200% by sliding the "Scaling" slider.

3.2 Operation box control motor

The operation box is connected to the control unit and option board (such as TB30) through digital and analog inputs. The user needs to perform BICO interconnection between the DI/DO of the control unit and the AI/O of TB30 with the control logic of the driver. For example, associate ON/OFF 1 with the digital input r722.0 of CU320, and associate the speed setting value with the analog input r4055 [0] of TB30. After the configuration is completed, the start stop, enable, reset, and speed control of the motor can be achieved through the switches and potentiometers on the operation box.

3.3 Basic Operation Panel Control Motor

BOP20 is an operation panel with backlight and six buttons, which can be directly installed on CU310 or CU320 control units. Through BOP20, users can switch driver objects, modify and display parameters, view fault information, and reset. When setting parameters, use the "P" key to enter parameter mode, and use the "Arrow" key to select parameter numbers and modify parameter values. For connector parameters (such as setting P840.0 to r0019.0), it is necessary to switch to BICO parameter display mode through the "Fn" key for setting.

3.4 Motor dynamic characteristic debugging

SCOUT software provides advanced debugging tools such as Trace, function generator, and measurement function (Bode plot).

Trace function: used to measure time-domain curves. Users can set the physical quantities to be observed (such as speed setting value, actual speed value, actual current value), set the sampling period and triggering method (such as bit triggering), and record the waveform during motor start-up or operation. By analyzing indicators such as overshoot and response time, dynamic response performance can be evaluated.

Function generator: used to generate periodic speed given signals (such as sine waves, square waves), combined with Trace function, can systematically test the dynamic response of the motor at different frequencies and amplitudes.

Measurement function (Bode diagram): Only applicable to servo control mode. This function is used to analyze the frequency response of the speed loop. Users can inject signals into the speed given channel, and the system automatically generates amplitude frequency and phase frequency Bode plots. By analyzing the cutoff frequency, phase margin, and amplitude margin, the stability and dynamic performance of the system can be accurately evaluated, and the proportional gain (P gain) and reset time of the speed loop can be adjusted accordingly.

Motor optimization technology

To achieve optimal control performance, SINAMICS S120 provides comprehensive motor optimization functions, including motor data calculation, static identification, and dynamic identification.

4.1 Automatic optimization

For Siemens standard motors, the "Automatic controller setting" function of SCOUT software can automatically optimize the controller dynamically. Before optimization, it is necessary to ensure that the motor is in a cold state, the brake is released, and the mechanical system is safe. During the optimization process, the system will automatically perform self-tuning of the speed loop parameters (proportional gain and integration time). After optimization, users can see significant improvements by comparing the Trace curves before and after optimization, such as a significant reduction in overshoot and faster response speed.

4.2 Optimization of Induction Motor

For induction motors (vector control mode), the optimization process includes three key steps:

Motor data calculation (P340): Calculate equivalent circuit parameters (stator/rotor impedance, inductance, etc.) based on motor nameplate data. This process does not require the use of a frequency converter.

Static identification of motor data (P1910): By enabling the frequency converter, the system automatically calculates key parameters such as stator cold impedance, rotor cold impedance, and main inductance. During the identification process, the motor may rotate slightly, but there is no torque output at the shaft end.

Dynamic identification of motor data (P1960): In the unloaded or loaded state of the motor, the system automatically performs speed loop parameter optimization, acceleration pre control (P1496) calculation, and system moment of inertia identification. After the optimization is completed, the system will update the new parameters to the speed regulator.

4.3 Optimization of servo motor

For servo motors, S120 also supports data calculation and static identification. By correctly configuring motor data (such as P305 rated current, P311 rated speed, P314 rated torque, P316 maximum speed, P323 pole pairs, etc.), the system can automatically calculate other parameters required for normal motor operation (such as P341 moment of inertia, P350 stator impedance, etc.). For high-precision servo applications, it is recommended to combine Trace and Bode diagram tools to finely manually adjust the speed and position loops.

Basic positioning function

Starting from firmware version V2.4, SINAMICS S120 integrates powerful basic positioning functions, including jog, zero return, limit, program steps, and manual data input (MDI).

5.1 Activation and Settings

When configuring the driver unit offline, the basic positioning function needs to be activated in the configuration wizard. After activation, the project navigation bar will display options for "Technology/Basic Positioner" and "Position control". Users can set and debug the positioning function through the control panel or expert parameter table.

5.2 Jog (Jog)

The jog function supports two modes:

Speed mode: When the button is pressed, the axis runs at the set speed, and when the button is released, it stops.

Position mode: Press the button and the rear axle will automatically stop when it reaches the set target position.

The user needs to set the jog speed, acceleration, and deceleration, and associate the ON/OFF 1 enable signal (P840) with the external switch.

5.3 Return to Zero (Homing)

The zeroing function varies depending on the encoder type:

Absolute value encoder: Only a one-time calibration is required during the initialization phase to set the zero point coordinates, without the need for repeated zeroing.

Incremental encoder: supports active and passive zeroing. Active zeroing can be achieved through three methods: encoder zero flag, external zero flag, or proximity switch+encoder zero flag. By defining parameters such as search direction, search speed, and proximity switch, the system automatically performs the zeroing action. Passive zeroing refers to dynamically resetting the current position to zero during the operation of the shaft, without affecting the operating state.

5.4 Limit

S120 supports dual protection of soft limit and hard limit. The hard limit is triggered by the switch input signal (P2569/P2570), and the signal is low and effective; The soft limit is set to the forward/reverse position range through parameters P2578/P2579. When the axis reaches the limit, the system will stop at maximum deceleration (P2573).

5.5 Program Steps (Traversing Blocks)

The program step mode allows users to preset up to 64 positioning steps, each of which can set parameters such as position, velocity, acceleration, etc. The program steps can be selected through a combination of digital input signals and can be automatically executed in sequence or in single steps. This function is suitable for applications that require repeated execution of fixed path positioning.

5.6 Manual Data Input (MDI)

The MDI mode provides a flexible interface for real-time control of the upper computer. This mode supports two operating modes:

Position mode: The axis operates according to the set position, speed, and acceleration/deceleration, and can perform absolute or relative positioning.

Speed mode: The axis runs at the set speed and acceleration/deceleration, without considering the actual position.

MDI data transmission is divided into two forms: single step transmission (relying on external switch confirmation) and continuous transmission (real-time data update, immediate effect). By adjusting the target position and running speed in real time through the upper computer, complex positioning programs can be constructed.

Communication technology

SINAMICS S120 supports direct communication with HMI and communication with PLC through DP bus.

6.1 S120 communicates directly with HMI

HMI (such as WinCC flexible) can be directly connected to S120 through PROFIBUS, without the need for PLC to modify parameters and simulate switch signals to control motor start and stop. When configuring communication, it is necessary to insert the HMI Station and driver in Step 7, set the network address, and establish a variable table. In the variable table, each parameter corresponds to a DB/DBW address, and its calculation rule is: DBW=1024 x device number+parameter index number. Users can directly read and write the parameters of the drive through the HMI screen.

6.2 DP bus communication between S7-300 and S120

Periodic data exchange (PZD) and non periodic data exchange (PKW) are implemented between S7-300 and S120 through the DP bus.

Periodic communication: used for real-time transmission of control words (such as controlling the start stop and enable of motors) and speed settings. In the standard message structure (such as PZD=2), control word 1 (STW1) and master set value (NSETP_B) are read and written through standard function blocks SFC14 and SFC15. The main setting value needs to be standardized, with 4000H corresponding to 100% and 7FFFH corresponding to 200%.

Non periodic communication: used for reading and writing parameters of the drive. Implement with SFC58 (write request) and SFC59 (read request) through the DPV1 function. Parameter requests and responses have fixed data structures, including request references, request IDs, device IDs, parameter quantities, parameter addresses, and parameter values. Users need to organize data blocks according to this structure to achieve reading and writing of any parameters of the drive.

DCC function

DCC (Drive Control Chart) is an optional feature package for SINAMICS S120, allowing users to write custom control logic in a graphical manner. Through DCC, users can create complex algorithms such as custom PID controllers, sine wave generators, logical operations, etc.

The basic process of DCC programming includes:

Add process packages: Execute "Select Technology Packages" online to load DCC functionality onto the target device.

Import Library Files: In offline mode, import DCC library files into the project to obtain the required functional blocks.

Offline programming: Drag and drop function blocks in DCC charts, connect input and output, and write control logic.

Assign execution group: Assign sampling periods (fixed execution group or free execution group) to DCC charts to avoid excessive computational load affecting system performance.

Compile and download: Compile the program and download it to the device.

DCC supports user-defined parameters (starting from P21500) and can interconnect the calculated variables with the control loop of the driver in a BICO manner, achieving highly flexible control schemes.