SINAMICS G120C: Speed Control with S7-1200 via Modbus RTU

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1 Task

NOTICE: This reference only can be used in China and India.

Introduction

SINAMICS G120C drives are able to exchange data via the RS485 interface and via Modbus RTU with a SINAMICS S7-1200 controller.

Overview of the Automation Task

The figure below provides an overview of the automation task.

2 Solution

Solution Overview

The following figure displays the most important components of the solution.

Delimitation

This application does not include a description of:

• SINAMICS G120C version
• BOP-2 operation of SINAMICS G120C

Basic knowledge of these topics is assumed.

Required Knowledge

Basic knowledge on TIA Portal is assumed.

2.2 Hardware and Software Components

2.2.1 Validity

This application example is valid for:

• TIA Portal V15 Professional
• S7-1200 CPU V4.1
• SINAMICS G120C Modbus RTU V4.7.6

2.2.2 Used Components

The application was generated with the following components:

Hardware Components

Standard Software Components

Sample Files and Projects

The following list includes all files and projects that are used in this example.

3 Basics of Modbus Introduction

Overview of Communication using Modbus RTU Communication

Modbus RTU (Remote Terminal Unit) is a standard protocol for communication in the network and uses the RS232 or RS422/485 connection for serial data transmission between Modbus devices in the network.

Modbus RTU uses a master/slave network in which all communication is triggered by a single master device while the slaves can only respond to the request of the master. The master sends a request to a slave address and only the slave with this slave address responds to the command.

NOTE: Exception: Modbus slave address 0 sends a broadcast frame to all slaves (without slave response).

Implementation with SIMATIC S7-1200

The application uses the following system instructions:

• MB_Comm_Load: To configure port for Modbus
• MB_Master: To communicate as Modbus master

3.1 Overview Modbus RTU System Instruction

3.1.1 MB_Comm_Load (S7-1200)

Description

The MB_Comm_Load instruction configures a communication module for communication by means of the Modbus protocol. An instance data block is automatically assigned when you add the MB_Comm_Load instruction in your program.

Parameter

The following table shows the parameters of MB_Comm_Load:

3.1.2 MB_Master (S7-1200)

Description

The MB_Master instruction communicates as Modbus master via a port configured by the MB_Comm_Load instruction. An instance data block is automatically assigned when you add the MB_Master instruction in your program. The MB_DB parameter of the MB_Comm_Load instruction must be connected to the (static) MB_DB parameter of the MB_Master instruction.

Parameter

The following table shows the parameters of MB_Master:

NOTE: The input value used in this application will described in chapter 4.

3.1.3 Drive Parameters for Drive Control via Modbus RTU

Modbus RTU is used to transfer cyclic process data and acyclic parameter data between precisely one master and up to 247 slaves.

Settings for Modbus RTU

NOTE: The input value used in this application will described in chapter 4.2.

3.2 Details of G120C Modbus Function

3.2.1 Control Word 1 (STW1)

3.2.2 Status Word 1 (ZSW1)

3.3 Installation

The figure below shows the hardware configuration of the application:

CAUTION: Wrong wiring can damage the drive! In this application, the three phase 400V power supply is used. It is a must for you to check the supply voltage; otherwise, the drive can be damaged!

NOTE: The position of the bus termination switch for the frame sizes FSD – FSF can be found in the G120C manual [3].

4 Configuration

4.1 Configure PLC Project

The screenshots in the following tables are from G120C_Modbus RTU at S7-1200 project.

Table 4-1: Creation of new project and configuration of the PLC

Step 1: Open TIA Portal V15 in your PC and then click Create new project.

Step 2: Assign the new project a name G120C_ModbusatS7-1200.

Step 3: Click Create to finish the creation of a new project.

Step 4: Click Project view to change to project view.

Step 1: In the project tree, go to Devices & Network view.

Step 2: In the Hardware catalog task card, locate the available SIMATIC CPU (for example S7-1217 DC/DC/DC), select the right firmware and use drag and drop to move it to the graphic area of the Network view. In this area and in the project tree, it will be created as PLC_1.

Step 3: Select the CPU with a suitable version (for example V4.2 (S7-1200)).

Step 1: In the graphic area, select the SIMATIC controller and go to the Device view.

Step 2: In the Hardware catalog task card, locate the CM1241 (RS422/RS485) communication module, version V2.2 and use drag and drop to move it to an allowed slot left to the CPU in the graphic area of the network view.

If necessary, change the Ethernet address. To do this, double-click the CPU to open its properties.

Step 1: In the Device view double click on the CM1241 to configure the property.

Step 2: Go to the IO-Link in the RS422/485 interface card.

Step 3: Change the Baud rate to 38.4kbps.

Create your user program or if you want to use the supplied sample program – copy the following objects from the sample program to your new project.

Step 1: Compile the PLC_1 device in order to detect possible errors.

Step 2: Save the project.

4.2 G120C Configuration

Table 4-2: Quick Commissioning via Startdrive in TIA Portal V15

Step 1: Select network view.

Step 2: In the Hardware catalog task card, select the suitable G120C USS IP20, (for example 2.2kW UF) and use drag and drop to move it to the graphic area of the Network view. In this area, it will be created as G120C USS/MB.

Step 3: Select the drive with a suitable version (for example V4.7.9).

Step 1: In the project tree, go to the Commissioning under G120C USS/MB.

Step 2: Click the Commissioning Wizard function to open Commissioning Wizard dialog.

Step 1: Choose Expert at the Application class card.

Step 2: Click Next.

NOTICE: This application also can be finished in Standard Drive Control or Dynamic Drive Control application class.

Step 1: Choose U/f control with linear characteristic at the Open-loop/close-loop control type card.

Step 2: Click Next.

Step 1: Choose USS Fieldbus at the defaults of the setpoints/command sources card.

Step 2: Click Next.

Step 1: Choose IEC-Motor (50 Hz, SI units) for Standard.

Step 2: Input 400 V for the drive unit line supply voltage.

Step 3: Choose Load duty cycle with high overload for vector drives for the power unit application.

Step 4: Click Next.

Step 1: Choose No filter at the drive options card.

Step 2: Click Next.

Step 1: Choose Enter motor data for the Motor configuration.

Step 2: Choose Induction motor for the motor type.

Step 3: Choose Star for the connection type.

Step 4: Input the required motor data accordingly.

Step 5: Choose No sensor for the temperature sensor.

Step 6: Click Next.

Step 1: Choose No motor holding brake available at the motor holding brake card.

Step 2: Click Next.

Step 1: Input important parameters accordingly at the important parameters card.

Step 2: Click Next.

Step 1: Choose Standard drive for the Technology application.

Step 2: Choose Inhibited for the motor identification.

Step 3: Choose Complete calculation for the Calculation of the motor parameters.

Step 4: Click Next.

Click Finish.

4.3 Programming the PLC Logic

In this application example, the SINAMICS G120C drive is controlled by S7-1217 CPU via Modbus communication. To achieve this control, the following instructions have been added to the program:

• MB_COMM_LOAD
• MB_MASTER

These FBs are called in the user defined "Modbus_Com"(FB1) function block. The figure 4-1 shows the program structure.

Table 4-3 is the details about the PLC logic programming.

Table 4-3 PLC Program

Step 1: Double-click Add new block in the program blocks.

Step 2: Select to create a new FB and give a name as Modbus_Comm.

Step 3: Click OK.

Configure the input and output as the table.

Configure the MB_Comm_Load function block as the table.

Configure the MB_Master function block as the table.

Open the Default tag table, and create the variables as the table.

Open OB1 and insert the FB1 to OB1, connect the input and output as the table.

Create a watch table as the table.

Step 1: Compile the program.

Step 2: Compiling is finished.

Step 3: Click download.

Click Load to load the program into PLC.

Click Finish and Save project.

4.4 Operating the Application

Table 4-2 Operation

Step 1: Go to Watch and force table: Modbus_Operation.

Step 2: Go Online.

Communication load enable:

1. Modify "Start Communication" with "True" (1).

2. When "Communication Done" is True,

3. Modify "Start Communication" "False" (0).

Start motor:

1. Set "Mode W/R" to 1.

2. Set "Master Address" to 40101.

3. Set "DATA_W/R" to 10.

1. Set "Master Address" to 40100.

2. Set "Data W/R" to 047E.

1. Set "Data W/R" to 047F.

Stop motor:

1. Set "Data W/R" to 047E.

5 Related Literature

6 Contact

Siemens Ltd., China

DF MC GMC-G

No. 18 Siemens Road

Jiangning Development Zone

Nanjing, 211100

China

mailto: mc_gmc_mp_asia.cn@siemens.com

7 History