SIEMENS SINAMICS S120 Servo Drive System Application Guide

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.