Acyclic Communication between Siemens S7-1200 and SINAMICS V20 via Modbus

Introduction

Effective from the firmware version V03.96.00.00 of SINAMICS V20 drive, it supports DS47 in Modbus communication. This enables access to all parameters in the V20 drive via acyclic communication.

The new firmware can be downloaded from the following link: https://support.industry.siemens.com/cs/ww/en/view/109767473

Overview of the Automation Task

Figure 1-1 provides an overview of the automation task. The setup involves a SIMATIC PLC S7-1217C communicating via Modbus with a SINAMICS V20 drive. The V20 drive powers a 3AC Asynchronous motor. A CM1241 module facilitates RS422/RS485 communication between the PLC and the V20. A PC/PG is connected via Ethernet.

Warranty and Liability

Note: Application Examples are not binding and do not claim to be complete. They are intended for typical applications and do not represent customer-specific solutions. Users are responsible for correct product usage and safe practices in application, installation, operation, and maintenance. Siemens is not liable for damages beyond the described liability clause. Changes may be made without prior notice. In case of deviations, other Siemens publications (e.g., Catalogs) take priority.

Siemens accepts no liability for the information in this document. Claims arising from the use of examples, information, programs, or data are excluded, except in cases of mandatory liability (e.g., German Product Liability Act), intent, gross negligence, injury to life, body, or health, warranty for quality, fraudulent concealment of defects, or breach of essential contractual conditions. Damages for breach of substantial contractual obligations are limited to foreseeable, contract-typical damages, unless intent, gross negligence, or injury to life, body, or health is involved. These provisions do not alter the burden of proof. Duplication or distribution of these Application Examples or excerpts requires express consent from Siemens AG.

Security Information

Siemens provides industrial security functions to support secure operation of plants, systems, machines, and networks. A holistic, state-of-the-art industrial security concept, including continuous maintenance, is necessary to protect against cyber threats. Siemens products and solutions are only one part of this concept. Customers are responsible for preventing unauthorized access to their systems. Systems should only be connected to enterprise networks or the internet with appropriate security measures (e.g., firewalls, network segmentation). Siemens' guidance on security measures should be followed. For more information, visit http://www.siemens.com/industrialsecurity.

Siemens continuously improves product security. Applying product updates as soon as available and using the latest product versions is strongly recommended. Using unsupported versions or failing to apply updates may increase exposure to cyber threats. Subscribe to the Siemens Industrial Security RSS Feed at http://www.siemens.com/industrialsecurity for product update information.

Solution

Solution Overview

Figure 2-1 displays the most important components of the solution. The system comprises an IO Supervisor (e.g., PC/PG), an IO controller (SIMATIC S7-1200 PLC), and an IO device (SINAMICS V20 drive).

Required Knowledge

Basic knowledge of TIA Portal, configuration of S7-1200 PLC with Modbus function in TIA Portal, and commission of SINAMICS V20 is assumed.

Hardware and Software Components

Validity

This application example is valid for TIA Portal V15.1 and SINAMICS V20 FW V03.96.00.00.

Used Components

Hardware Components

Standard Software Components

Sample Files and Projects

Table 2-3 includes all files and projects used in this example.

Acyclic Data Exchange

Description

The acyclic data exchange mode allows for the exchange of large "user data" using PLC function blocks. The data block structure should follow the DS47 data structure. Communication is realized via Modbus registers 40601 to 40722. Register 40601 controls acyclic communication, register 40602 contains the function code (47), and registers 40603 to 40722 hold user data.

Diagram of Acyclic Data Exchange

Figure 3-1 describes the principle of acyclic data exchange. It shows a Controller/Supervisor initiating a parameter request. The Device processes this request. Communication involves 'Write.req with data' and 'Write.res without data' for writing, and 'Read.req without data' and 'Read.res with data' for reading. The process includes parameter processing and parameter response.

Overview of Acyclic Communication

Table 3-1 shows the overview structure of acyclic communication, detailing values in registers 40601-40722 for writing and activating access, and response data for successful or error requests. It also lists error codes (e.g., 1 hex: Invalid length, 2 hex: Invalid state, 3 hex: Invalid function code, 4 hex: Response not ready, 5 hex: Internal error) and notes that incorrect parameter access is logged in registers 40603 to 40722.

Data Structure for Parameter Reading

Table 3-2 details the data structure for parameter reading tasks, outlining the message header, parameter structure, and register assignments.

Data Structure for Successful Reading Operation

Table 3-3 shows the data structure for a successful reading operation, similar to Table 3-2 but specific to successful reads.

Data Structure for Non-Successful Reading Operation

Table 3-4 shows the data structure for a non-successful reading operation, detailing the message header and error code.

Data Structure for Writing Parameters

Table 3-5 details the data structure for writing parameters, including message header, parameter properties, number, index, data format, and parameter values.

Operation

Hardware Installation

Figure 4-1 illustrates the main power supply diagram for the V20 drive and PLC. It shows AC 200V power connection to the V20 drive and a 24V DC supply to the CM1241 module and S7-1200 CPU. Figure 4-2 details the communication wiring between the CM1241 and V20 drive using RS485 connections (P+ and N-).

V20 Drive Parameter Setting

Table 4-1 lists the Modbus communication parameters to be set in the V20 drive, including baud rate, telegram off time, Modbus address, reply timeout, RS485 protocol selection, parity, and stop bits.

PLC Engineering

Configuration and Programming

The configuration and programming steps are detailed in Table 4-2:

Read Parameters

This section describes the task of reading parameters from the drive, specifically parameter P1121. Table 4-3 outlines the operation sequence, involving loading the Modbus command, setting parameters like "LoadRequest" and "DataLength", sending read requests, and interpreting the response. For example, setting "LoadRequest" to TRUE loads the Modbus command, and setting "ReadRequest" to TRUE initiates the parameter reading operation. "Response40606" and "Response40607" contain the parameter value, e.g., P1121=10.0.

Write Multiple Parameters

This section covers writing parameters to the drive, specifically P1121=12.15. Table 4-4 details the operation sequence, including setting "DataLength" and "WriteRequest" to TRUE, and verifying the change in the drive. For instance, setting "DataLength" to 10 and updating "Request40601" through "Request40610" with specific values, then setting "WriteRequest" to TRUE, changes the drive's P1121 value to 12.15.

Related Literature

Table 5-1 lists related resources, including the Siemens Industry Online Support portal and the download page for this specific entry.

Contact

Siemens Ltd., China

DI MC GMC

No. 18 Siemens Road

Jiangning Development Zone

Nanjing, 211100

China

Email: mc_gmc_mp_asia.cn@siemens.com

History

Table 9-1 shows the document history. Version V1.0 was released in 07/2020 as the first version.