39040038 Datasync Doku v21 En

8/18/2019 39040038 Datasync Doku v21 En

1/44

Applications & Tools Answers for industry.

Cover

Communication: Performant Data SynchronizationBetween Several Field and One Head

PLC

S7-1200 Set 17

Application Description June 2013


2/44

Table of Contents

2Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G

2 0 1 3 A l l r i g h t s r e s e r v e d

Warranty and Liability

Note The Application Examples are not binding and do not claim to be completeregarding the circuits shown, equipping and any eventuality. The ApplicationExamples do not represent customer-specific solutions. They are only intendedto provide support for typical applications. You are responsible for ensuring thatthe described products are used correctly. These Application Examples do notrelieve you of the responsibility to use safe practices in application, installation,operation and maintenance. When using these Application Examples, yourecognize that we cannot be made liable for any damage/claims beyond theliability clause described. We reserve the right to make changes to these Application Examples at any time without prior notice. If there are any deviationsbetween the recommendations provided in these application examples and otherSiemens publications – e.g. Catalogs – the contents of the other documentshave priority.

We do not accept any liability for the information contained in this document.

Any claims against us – based on whatever legal reason – resulting from the use ofthe examples, information, programs, engineering and performance data etc.,described in this Application Example shall be excluded. Such an exclusion shallnot apply in the case of mandatory liability, e.g. under the German Product Liability Act (“Produkthaftungsgesetz”), in case of intent, gross negligence, or injury of life,body or health, guarantee for the quality of a product, fraudulent concealment of adeficiency or breach of a condition which goes to the root of the contract(“wesentliche Vertragspflichten”). The damages for a breach of a substantialcontractual obligation are, however, limited to the foreseeable damage, typical forthe type of contract, except in the event of intent or gross negligence or injury tolife, body or health. The above provisions do not imply a change of the burden of

proof to your detriment.

Any form of duplication or distribution of these Application Examples or excerptshereof is prohibited without the expressed consent of Siemens Industry Sector.

Caution: The functions and solutions described in this article confine themselves to therealization of the automation task predominantly. Please take into accountfurthermore that corresponding protective measures have to be taken up in thecontext of Industrial Security when connecting your equipment to other parts of theplant, the enterprise network or the Internet. Further information can be foundunder the Entry ID 50203404.

http://support.automation.siemens.com/WW/view/en/50203404

http://support.automation.siemens.com/WW/view/en/50203404http://support.automation.siemens.com/WW/view/en/50203404


3/44

Table of Contents

DatasyncV21, Entry ID: 39040038 3

C o p y r i g h t S

i e

m e n s A G


Table of ContentsWarranty and Liability .............................................................................................. 2

1 Task................................................................................................................. 4

2 Solution overview ........................................................................................... 5

2.1 Description of the core functionality.................................................... 7 2.1.1 Overview and description of the user interface ................................... 7 2.1.2 Synchronization of the data................................................................ 9 2.1.3 Simulation of the data in the field PLCs ............................................ 11 2.1.4 Time synchronization ....................................................................... 12 2.2 Hardware and software components used ....................................... 12

3 The blocks of the data synchronization ...................................................... 14

3.1 Complete overview of the program blocks........................................ 14 3.1.1 Program overview of the head PLC.................................................. 14 3.1.2 Program sequence in the field PLC .................................................. 15

3.2 Data blocks ..................................................................................... 16 3.2.1 The data block of the head PLC ....................................................... 16 3.2.2 The data block of the field PLC ........................................................ 20 3.3 The data block “DATASYNC_X” ...................................................... 22

4 Mechanisms of data synchronization .......................................................... 25

4.1 Control process in the overview ....................................................... 25 4.2 Functioning of the function block DATASYNC_X .............................. 26 4.3 Behavior in the event of a power failure ........................................... 27

5 Performance Measurement .......................................................................... 28

5.1 Conception of the measurement ...................................................... 28 5.2 Values of the performance measurement ......................................... 30

5.3 Result .............................................................................................. 31 6 Installation .................................................................................................... 32

6.1 Hardware installation ....................................................................... 32 6.2 Software installation......................................................................... 33

7 Starting up the Application .......................................................................... 34

7.1 Assigning the IP addresses.............................................................. 34 7.2 Download the PLCs and the panels ................................................. 37

8 Operating the Application ............................................................................ 40

9 Related literature .......................................................................................... 42

10 History .......................................................................................................... 42

11 Appendix A: Measured Data ........................................................................ 43

11.1 Head: S7-1200; 6 ms program load ................................................. 43 11.2 Head: S7-1200; 50 ms program load ............................................... 43 11.3 Head: WinAC; 6 ms program load .................................................... 44 11.4 Head: WinAC; 50 ms program load .................................................. 44


4/44

1 Task

4Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


1 Task

Introduction

For synchronization tasks and for the exchange of control and status informationamong a head PLC and field PLCs, e.g. for solar trackers in solar parks, aperformant cyclic communication system is needed.

For reducing the data transfer, e.g. to an HMI or when a remote supervision isused, the data are to be exchanged in bundles by means of a data concentrator(here: head PLC).

The figure below provides an overview of the automation task.

Figure 1-1

Field PLC 1 Field PLC 2 Field PLC n

Head PLC HMI

Description of the automation problem A module for the data synchronization and the exchange of control and statusinformation among the head PLC and several field PLCs is to be developed. It is toassume the following task independently:

Supply of all the field PLCs with the same or different sets of data from thehead PLC (down sync).

Updating the sets of data from all the field PLCs in the head PLC (up sync).

Requirements of the automation task

The following requirements are posed to the block:

Optimal and performant utilization of the available connection resources of the

head and field PLC. Simple adaptation to variable quantities (data volume sent and received).

To be used with S7-1200 and S7-300/400/IPC with Win AC.

The programming is to be done mainly with SCL.


5/44

2 Solution overview


C o p y r i g h t S

i e

m e n s A G


2 Solution overview

Display

The following figure gives a schematic overview of the most important componentsof the solution:

Figure 2-1

HMI Panel S7-1200 IPC + WinAC

Field PLCs S7-1200 (e.g. in solar trackers) with

function block DATASYNC_SUB

DATASYNC_

HEAD

Possible Head PLCs with function block

DATASYNC_HEAD

DATASYNC_

SUB

DATASYNC_

HEAD

DATASYNC_

SUB

DATASYNC_

SUB

DATASYNC_

SUB

Setup

The application example is demonstrated in a concrete example - controlling solartrackers.

The expression solar tracker means solar energy systems which can be trackedaccording to the position of the sun to ensure the best possible energy yields.

For the field PLC, a CPU S7-1200 is used in this example. For the sake of a betterclarity, the number has been reduced to four.

For the head PLC, this solution uses two types of devices:

An S7-1200 controller

An S7-300/400 / IPC with WinAC


6/44

2 Solution overview

6Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


Description

With the function block “DATASYNC_X” (X:= HEAD or SUB), a block has beendeveloped that assumes the control of the data synchronization automatically.

The head PLC sequentially establishes an ISO-on-TCP communication connectionwith each field PLC and terminates it again. Data is sent to the field PLCs and datais received from them. After all field PLCs have been operated, the process isrepeated.The following figure summarizes the data exchanged between head PLC and fieldPLCs.

Figure 2-2

Field PLC1..4

Head PLC

Data structure of the Head-PLC:

• Geographic position (longitude / latitude)

• Requirement time synchronization

• Current time

Data structure of the Field PLCs:

• Zenith / azimuth angle

• Current weather data (temperature / wind)

• Production data

It is always the head PLC which takes the initiative.

Since the field PLCs are only passive and wait for the request from the head PLC,there is a separate “DATASYNC_SUB” block for the field PLC. Its task is thesupply and disposal of the send and receive data.

The data communication among the PLCs is displayed in images by the HMI panel.

For displaying and updating the images, the panel uses the send and receive dataof the head PLC.

Delimitation

This application does not include any

information concerning the programming language SCL.

basic information on industrial Ethernet.

information on astronomic algorithm or solar tracking.

Basic knowledge of these topics is assumed.


7/44

2 Solution overview


C o p y r i g h t S

i e

m e n s A G


2.1 Description of the core functionality

2.1.1 Overview and description of the user interface

For commissioning, operation and monitoring there is

an overview for operating and configuring the solar trackers.

an information surface for every field PLC.

The user interface has been realized in a comfort panel TP700.

For updating the images with the current data, an HMI connection between thepanel and the head PLC has been configured.

Overview head PLC

In this overview screen, all the field PLCs can be configured when their geographicposition is entered and the time synchronization can be triggered.

The longitude and the latitude are to be entered in decimal degrees.

Figure 2-3


8/44

2 Solution overview

8Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


Information screen

There is a separate information screen for every field PLC. The calculated zenithand azimuth angles and simulated weather information and production data are

displayed here.Figure 2-4


9/44

2 Solution overview


C o p y r i g h t S

i e

m e n s A G


2.1.2 Synchronization of the data

Schematic layout

The data synchronization between the head PLC and the field PLCs is donecomfortably with the function block “DATASYNC_X”.

This block implements the cyclic and performant data exchange between the headPLC and the field PLCs.

The defined data structure is sent from the head PLC to the field PLC when theconnection has been built up on both sides. The field PLC waits for reception andthen sends its own data structure to the head PLC(see Figure 2-2).

As soon as the head PLC has received the data sent from the field PLC, the dataexchange is completed. The connection is disconnected.

The exchanged data structures and the IP addresses of the field PLCs are stored

in different global data blocks.

Increasing the performance by parallel connections

There is the possibility of operating several field PLCs in parallel (multiplexing). Thefunction block “DATASYNC_HEAD” can be called with a different instance datablock in the OB1 of the head PLC for every available connection. The maximumnumber of calls is limited by the available connection resources of the head PLC.

In the present Application Example, these parallel connections are being used.

Note The maximum admissible number of parallel connections varies depending in thehead PLC.

S7-1200 supports no more than eight connections.

S7-300/400 / IPC with WinAC supports up to 32 connections.


10/44

2 Solution overview

10Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


The following graphic shows the possibility of increasing the performance bymultiplexing.

Figure 2-5

DATASYNC_

HEAD

DATASYNC_

HEAD

DATASYNC_

HEADHEAD PLC

DATASYNC_

FIELD

DATASYNC_

FIELD

DATASYNC_

FIELDFIELD PLCs

DATASYNC_

FIELD…

1 2 3 z

1

3

2 …

z

Multiplex z field PLCs

via several channels

n available

connection

resources

DATASYNC_

HEAD…

Example:

An S7-1200 CPU is used as the head PLC, and there are 12 field PLCs. Thismakes possible the following combinations:

Number of available connection resources: n = 8

Number of field PLCs: z = 12

Therefore, the “DATASYNC_HEAD” block can be called in eight instances. Thereare eight communication channels for the 12 field PLCs.In the dynamic multiplex mode, the 12 field PLCs are synchronized through the

eight channels.


11/44

2 Solution overview


C o p y r i g h t S

i e

m e n s A G


Communication blocks

The communication between the head PLC and the field PLCs is done by an ISO-on-TOP connection.

The connecting and disconnecting process and the sending and receiving of thedata is internally carried out in the “DATASYNC_X” block by means of the followingstandard communication blocks:

Table 2-1

Block Description

TCON The TCON command establishes the communicationconnection.

TDISCON TDISCON establishes the connection to the partner station.

TSEND TSEND sends data through an existing communicationconnection.

TRCV The counterpart to TSEND is TRCV. With this command, data

can be received through an existing communicationconnection.

2.1.3 Simulation of the data in the field PLCs

Determining the position of the sun, using an astronomical algorithm

Depending on the position of the earth, the position of the sun can be calculatedwith the aid of an astronomical algorithm, using details on longitude and latitude.This position of the sun is described with the azimuth angle for the horizontalalignment and zenith for the vertical alignment. To calculate the position of the sun,the algorithm needs the Universal Time Coordinated (UTC) to take the earth’s

changing orbital period around its own axis into account.

Table 2-2

Parameters Unit Description

Longitude [°] Longitude from 0° (North) to 360 °

Latitude [°] Latitude from -90° (South pole) to +90° on the Northpole

In this Application Example, the astronomic algorithm is calculated with the functionblock SimpleAstroAlgorithm in the cyclic program of the field PLCs.

Simulation of the weather and production data in the field PLCs

The simulation of data that are sent from the field PLCs to the head PLC is done bytime-controlled OBs and a mathematical calculation.


12/44

2 Solution overview

12Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


2.1.4 Time synchronization

For the visualization screen the time synchronization of all the CPUs can be

synchronized with the current UTC time in the head PLC. The synchronizationtakes place in two steps:

1. With a trigger command, the head PLC reads out the current time and datehead PLC with the button Activate Timesync by means of the function blockRD_SYS_T. This information is stored in the sending reports of the field PLCsand the time synchronization bit there is set.

2. The field PLCs receive the information with the next data synchronization andrecognize the requirement to carry out a time synchronization. Then they adapttheir real time clocks to the times they received.

2.2 Hardware and software components used

The application was set up with the following components:

Hardware components

Table 2-3

Component No. Order number Note

CPU 1215C AC/DC/Rly 1 6ES7 215-1BG31-0XB0 Head PLC

IPC 277D PN/IEBundle with WinAC RTX (F)

1 6ES7 647-8A… Head PLC

CPU 1214C DC/DC/DC 1 6ES7 214-1AE30-0XB0 Field PLCField PLC1

CPU 1212C DC/DC/DC 3 6ES7 212-1AE31-0XB0 Field PLCs

Field PLC2 - 4HMI panel TP700 Comfort 1 6AV2124-0GC01-0AX0

SCALANCE X208 1 6GK5208-0BA10-2AA3

PG / PC 1 For loading the headand field PLCs

Standard software components

Table 2-4

Component No. Order number Note

STEP 7 Professional V12 1 6ES7822-0A…

WinCC Professional 1 6AV210…


13/44

2 Solution overview


C o p y r i g h t S

i e

m e n s A G


Example files and projects

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

Table 2-5Component Note

39040038_DATASYNC_CODE_v20.zip This zip file contains two STEP 7 V12projects.

DATASYNC_1200 for the S7-1200CPU as the head PLC.

DATASYNC_IPC for the IPC withWinAC as the head PLC

39040038_DATASYNC_DOKU_v20_d.pdf This document.


14/44

3 The blocks of the data synchronization

14Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G



3.1 Complete overview of the program blocks

3.1.1 Program overview of the head PLC

Program structure

The following graphic shows the complete user program of the head PLC.

Figure 3-1

DATASYNC_HE

AD

iDB

OB 1

DATASYNC_HE

AD

RD_SYS_T

DB_IPADDRESS DB_MANAGE

DB_RCV_

DATA

DB_SND_

DATA

DB_STATE

iDB

DATASYNC_HE AD

iDB

DATASYNC_

HEAD

iDB

TCON

TRCV

TSEND

TDISCON

Description

Table 3-1

Block Note

DATASYNC_HEAD Function block for data synchronization; to enable a paralleldata synchronization with all the other field PLCs (solar tracker),the block is called several times - each time with a differentinstance data block - cyclically in the application program.

Per field PLC, there is one call of the FB in the OB1 in this Application Example (4 field PLCs 4 calls).

TCON, TRCV, TSENDand TDISCON

Function blocks for the communication (see also chapter 2.1.2);the enable the data communication.

DB_IPADDRESS Data block; contains the IP addresses of all the field PLCs.

DB_STATE Data block; contains status information of every field PLC.


15/44



C o p y r i g h t S

i e

m e n s A G


Block Note

DB_MANAGE Data block; contains information setting up the communicationchannels.

DB_RCV_DATA Data block; contains the receive data of the field PLC inseparate structures.

DB_SND_DATA Data block; contains the receive data of the field PLC inseparate structures.

RD_SYS_T Function block; responsible for reading out the current and localtime for the time synchronization.

3.1.2 Program sequence in the field PLC

Program structure

The following graphic shows the complete user program of the field PLCs.

Figure 3-2

DATASYNC_

SUB

iDB

OB 1

SimpleAstro

Algorithm

DB_SND_RCV

_DATA

TCON

TRCV

TSEND

WR_SYS_T

OB 30

OB 31


16/44


16Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


Description

Table 3-2

Block Note

DATASYNC_SUB Function block for data synchronization

TCON, TRCV, TSEND Function blocks for the communication (see also chapter 2.1.2);the enable the data communication.

DB_SND_RCV_DATA Data block; contains sending data for and receiving data fromthe head PLC.

SimpleAstroAlgorithm Function block; calculates the position of the sun on the basis ofthe position data (longitude and latitude) sent.

WR_SYS_T Function block; responsible for reading out the current and localtime for the time synchronization.

OB 30, OB 31 Time-controlled organization block for the simulation of theweather and production data

3.2 Data blocks

3.2.1 The data block of the head PLC

Overview

For establishing a communication connection, the data block “DATASYNC_HEAD”needs more information

about the field PLC

– IP addresses

– number of project engineers

– feedback concerning the status of the connection

the maximum number of possible parallel connections

– with an S7-1200 as head PLC: eight connections

– with an S7-300/400 / WinAC as head PLC: 32 connections

about the sending and receive structure

– size of each structure

– storage location

All these pieces of information are stored in different global data blocks:

Table 3-3

Data block Responsible for...

DB_IPADDRESS IP addresses of the field PLCs used

DB_MANAGE Number of field PLCs, length of the structures, global trigger forstarting the data synchronization

DB_RCV_DATA Storage location for the received data of every field PLCs

DB_SND_DATA Storage for the data to be sent

DB_STATE Communication status of every field PLC

These data blocks are described in the following:


17/44



C o p y r i g h t S

i e

m e n s A G


DB_IPADDRESS

In the global data block “DB_IPADDRESS”, the IP addresses for every field PLCare stored. Every IP address is defined as the data type “Struct”, and divided into

the segments “REM_1”, “REM_2”, “REM_3” and “REM_4” with the data type“USInt” (S7-1200) or “byte” (WinAC).

Figure 3-3

DB_MANAGE

The global data block “DB_MANAGE” serves for the communication of theconnections.

Figure 3-4

In the parameter “Act_SubStation”, the “DATASYNC_HEAD” blocks store thenumber of the last field PLC they called, or read the number of the next free fieldPLC.

The parameter “Nr_of_Substations” contains the number of field PLCs.

“REQ_x” are Bool variables for using (REY_x “True”) or the release (REQ_x

“False”) of a “DATASYNC_HEAD” block and therefore with a connection resource.For every “DATASYNC_HEAD” one bit is provided.

The parameters “LEN_SNDData” and “LEN_RCVData” each contain the length ofthe send and receive structure in number of bytes.


18/44


18Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


DB_STATE

In this data block, the communication status of each field PLC is listed and updatedand observed while “DATASYNC_HEAD” is running. For every station, one byte is

provided.Figure 3-5

The value of the status byte is to be interpreted as follows:

Table 3-4

Value Meaning

1 A connection between the head and the field PLCs is being established.

2 The connection between the head and the field PLC was successfullyestablished.

3 The data exchange between the head and the field PLC is completed and thecommunication connection is disconnected.

4 The first attempt to establish a connection between the head and the field PLCfailed.

5 From the second attempt onwards (the status was “4” before), the system tries toestablish a connection for a certain period of time.

0 Field PLC available for access.

DB_SND_DATA and DB_RCV_DATAThe two data blocks contain the data to be synchronized.

The following rule is applied:

The structure of the send data of the head PLC must be identical with thereceive structure of the field PLC.

The structure of the receive data of the head PLC must be identical with thesend structure of the field PLC.

The send and receive structure is the same for every field PLC.

For every field PLC one structure is stored in the data block.

Since the send and receive structure must be identical for all field PLCs, werecommend the use of templates (PLC data types).

PLC data types are defined data structures which can be opened several times inthe program. The structure of a PLC data type is composed of several componentswhich can have different data types. There are the following possibilities of usingPLC data types:

PLC data types can be used as data types for variables in a variabledeclaration of code blocks or in data blocks

PLC data types can be used as templates for creating global data blocks withthe same data structure.


19/44



C o p y r i g h t S

i e

m e n s A G


UDT_HEAD_RCV_STRUCT

As the data type of the receive data, the template “UDT_HEAD_RCV_-STRUCT” isused:

Figure 3-6

With this template, one sector is defined for every field PLC in the receive datablock “DB_RCV_DATA” of the head PLC.

Figure 3-7

UDT_HEAD_SND_STRUCT


Figure 3-8

With this template, one sector is defined for every field PLC in the send data block“DB_SND_DATA” of the head PLC.

Figure 3-9


20/44


20Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


3.2.2 The data block of the field PLC

DB_SND_RCV_DATA

Since this communication connection is always initiated by the head PLC, it issufficient to integrate only one data block into the user program of the field PLC.

The global data block “DB_SND_RCV_DATA” contains the send and receivestructure for the data exchange.

The rules for the send and receive structure are also applied here:

The structure of the send data of the field PLC must be identical with thereceive structure of the head PLC.

The structure of the receive data of the field PLC must be identical with thesend structure of the head PLC.

Here, the data block template is also created by a template.

UDT_SUB_SND_STRUCT

As the data type of the receive data, the template “UDT_SUB_SND_-STRUCT” isused:

Figure 3-10

UDT_SUB_RCV_STRUCT


Figure 3-11


21/44



C o p y r i g h t S

i e

m e n s A G


With these templates, the data block of the field PLC is defined.

Figure 3-12

Note Since the send and receive structures must be identical for all field PLCs, thesetemplates can be reused for the other field PLCs.


22/44


22Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


3.3 The data block “DATASYNC_X”

Description

The function block “DATASYNC_X” controls the data synchronization between thehead and the field PLC.

For the head and the field PLC, there are different “DATASYNC_X” blocks whichdiffer as far as their functionalities scope and therefore their interface configurationare concerned.

Interfaces for the head PLC

Calling the block has been described as follows:

Figure 3-13


23/44



C o p y r i g h t S

i e

m e n s A G


Parameters

The parameters have the following meaning:

Table 3-5

Parameters Type Datatype

Meaning

ID

INPUT

WORD A unique number for the communication connection. Ifthe “DATASYNC_HEAD” is called several times, adifferent number must be selected.

REQ BOOL With “True” the data synchronization is triggered and asupply resource is assigned.

With “False”" the synchronization process is stopped andthe approval of the communication is initiated

NR_SUBSTATIONS INT Number of project field PLCs

DB_NR_IPADDRESS Number of the data block“DB_IPADDRESS”.

DB_NR_STATE Number of the data block“DB_STATE”.

DB_NR_SND_DATA Number of the data block“DB_SND_DATA”.

LEN_SND_DATA Length of the send structure

DB_NR_RCV_DATA Number of the data block“DB_RCV_DATA”.

LEN_RCV_DATA Length of the receive structure

IDB_NR_LOC Number of the instance block of this“DATASYNC_HEAD” block

ACT_SUBNET_NUM

BER

IN/

OUT

INT Variable for interim storage of the field PLC used last.

RSC_FREE OUT BOOL With “True”, the connection resource is released, as soonas REQ has been set to “False”.


24/44


24Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


Interfaces for the field PLC

Calling the block has been described as follows:

Figure 3-14

Parameters

The parameters have the following meaning:

Table 3-6

Parameters Type Data type Meaning

ID

INPUT

WORD A unique number for the communication connection.

REM_IP1

USINT

First part of the IP address of the head PLC

REM_IP2 Second part of the IP address of the head PLC

REM_IP3 Third part of the IP address of the head PLC

REM_IP4 Fourth part of the IP address of the head PLC

SND_DATAIN/ OUT VARIANT

Pointer to the send section

RCV_DATA Pointer to the receive section


25/44

4 Mechanisms of data synchronization


C o p y r i g h t S

i e

m e n s A G



4.1 Control process in the overview

With the block “DTASYNC_X” a possibility of replacing control and statusinformation between the head PLC and the field PLCs (solar trackers in solarparks) automatically and effectively and of synchronizing the time has beenrealized.

The following diagram shows the process in the head and in a field PLCs:

Figure 4-1

Initiation of the data

synchronization

Find next free field PLC

Copy IP address of the field

PLC from the global DB into

the instance DB

Disconnect the connection

Establish connection

Copy send structure from the

global DB to the instance DB

Send data to the free field PLC

Receive data from the field PLC

Copy receive structure from

the instance DB

to the global DB

Establish connection

Copy send structures from theglobal DB to the instance DB

Receive data from the

head PLC

Send data to the central PLC

Copy receive structure from

the instance DB

into the global DB

Head PLC with

DATASYNC_HEAD

Field PLC z with

DATASYNC_SUB


26/44


26Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


4.2 Functioning of the function block DATASYNC_X

In this chapter, the functioning of the “DATASYNC_X” block is briefly explained.

For more details, please refer to the program code which has good comments.

Establish communication connection

The command “TCON” establishes and builds up the communication connection. As soon as the connection is working, it is automatically maintained and monitoredby the CPU. “TCON” is carried out in several cycles.

The block receives the required information such as

the IP address of the connection partner

the number of the connection

through the input parameters in the “DATASYNC_X” block.

Send data

The command “TSEND” sends data through an existing communicationconnection. “TSEND” is carried out in several cycles.

The block receives the required information through the input parameters in the“DATASYNC_X” block.

Receive data

The command “TRCV” sends data through an existing communication connection.“TRCV” is carried out in several cycles.

The received data are buffered in a receive area, and then they are transmitted tothe receive area.

The receive area is defined by the following two dimensions:

pointer at the beginning of the area

length of the area in number of bytes.

This information is transmitted by the parameters at the “DATASYNC_X” block.

Establish a communication connection (head PLCs only)

The instruction “TDISCON” disconnects the communication connection of the CPUto the communication partner. “TDISCON” is a command working over severalcycles.When the connection has been disconnected successfully, the ID entered in the FB“TCON” is no longer valid and can therefore be neither used for sending nor for

receiving.


27/44



C o p y r i g h t S

i e

m e n s A G


Copy data

The transmission of the data (IP address, send and receive structure) between aglobal data block and an instance data block is done by MOVE commands.

The storage address where the information of the current field PLC is located, isdetermined by an Offset calculation.

The following graphic shows the principle with the example of an IP address.The global data block “DB_IPADDRESS” contains the IP address for all the fieldPLCs. The block “DATASYNC-HEAD” calculates the Offset for the storage area ofthe IP address of the field PLC to be edited on the basis of the IN/OUT variables“ACT_SUBNET_Number”.

Figure 4-2

IP address

Field PLC 1

IP addresse

Field PLC 2

IP address

Field PLC 3

IP address

Field PLC z

4- Bytes

Global DB

DB_IPADDRESS

IP address

Field PLC 3

Instance DB

DATASYNC-HEAD

Offset: 2 * 4-Bytes

ACT_SUBNET_NUMBER:=3

4.3 Behavior in the event of a power failure

If more than one field PLCs are involved in the data synchronization, it must bemade sure that the synchronization mechanism to the intact field PLCs is notblocked in the event if one or more field PLCs break down (e.g. because theconnection cable is pulled out).

To solve this problem, the status of the communication connection of each fieldPLCs is documented in the data block “DB_STATE” (see chapter 3.2.1). Thesestatus values are compiled by means of the status parameters “TCON_Busy” or

“TRCV_Error” of the communication blocks (TCON, TSEND, TRCV, TDISCON).

If an interruption of the communication to a field PLC is detected (status value: 4),the block “DATASYNC_HEAD” tries to reestablish the connection for a definedperiod of time (status value: 5). If it does not succeed, this will be acknowledgedwith an error message.

As soon as a connection has been reestablished, the error message is deleted.


28/44

5 Performance Measurement

28Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G



Objective

In order to be able to describe the performance of the program, a performancemeasurement is carried out.

The following chapter describes:

the concept of the performance measurement.

the measurement results.

an analysis of the values.

5.1 Conception of the measurement

Structure

The following hardware constellation was used for the measurement: Constellation 1:

– Head PLC S7-1200-CPU

– Field PLCs: up to 32 S7-1200-CPUs

Constellation 2:

– Head PLC IPC

– Field PLCs: up to 32 S7-1200-CPUs

These components were interconnected in accordance with the instructions inchapter 6.

Figure 5-1

S7-1200 IPC + WinAC

1, 4, 8, 16, 32 Field-PLCs S7-1200 with function

block DATASYNC_SUB

Head PLCs with up to eight function blocks“DATASYNC_HEAD”

DATASYNC_

SUB

DATASYNC_

HEAD

DATASYNC_

SUB

DATASYNC_

HEADDATASYNC_

HEADDATASYNC_

HEAD

DATASYNC_

SUB

DATASYNC_

HEADDATASYNC_

HEADDATASYNC_

HEADDATASYNC_

HEAD

. . .

In the user program of the head PLC, up to eight function blocks

DATASYNCH_HEAD are called in the OB1 (see also chapter 2.1.2).


29/44



C o p y r i g h t S

i e

m e n s A G


Measuring scenarios

For the performance measurement, several variants were measured that differ inthe following aspects:

type of head PLC number of substations

data load

program load.

The following table shows the values:

Table 5-1

Parameters Settings

Type of head PLC S7-1200 (CPU 1215), WinAC (IPC 227D)

Number of substations 1, 4, 8, 16, 32

Size of the area to be synchronized (in

bytes)

10, 100, 200, 1000

Program load (in ms) 6, 50

Measure cycle

The measuring clock is started before the connection to the first substation is builtup. The end of a measure cycle is the point in time when all the substations havebeen synchronized once.


30/44


30Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


5.2 Values of the performance measurement

Data conditioning

To avoid systematic errors, the measuring parameters are determined by repeatedmeasurement.

100 subsequent measurements are determined and processed as representativemeasuring data. All the values and the maximum and the minimum synchronizationtime of a measure of a series of measurements are listed in the Annex (seechapter 11).

Diagrams

The following diagrams show the time for a synchronization cycle the S7-1200(gray line) needs as compared to the WinAC (blue line) for two measuringscenarios.

Figure 5-2

Figure 5-3

Detailed values

The detailed values of the performance measurement are listed in chapter 11

“ Appendix A: Measured Data”.

Number of substations

200 b te, 6 ms ro ram load

T i m e i n m s

Number of substations

1000 b te, 50 ms ro ram load

T

i m e i n m s


31/44



C o p y r i g h t S

i e

m e n s A G


5.3 Result

Overview

These are the results of the individual measurements: The WinAC always synchronizes the data fields quicker than the S7-1200.

The higher the number of substations, the higher is the time differencebetween the synchronization for the S7-1200 and the Win AC.

The synchronization time increases clearly when more than 8 substations arebeing used.

The synchronization time increases with the number of substations and thevolume of the data to be synchronized.

Analysis

The measured values allow the following conclusions:

The first two observations can be attributed to the increased performance ofthe current Intel atomic chip of the IPC as compared to the processor of theS7-1200 CPU.

Up to a number of 8 substations there is a call of the FB “DATASYNC_HEAD”per substation in the OB1. Accordingly, the computing time increases, but thesynchronization time does not increase proportionally to the number ofsubstations, since the connection resources can be used in parallel.

From a number of 8 substations or more, the maximum number of connectionresources of the two head PLC is used up, so that the parallel processing iscompleted by a serial processing. For more details about the behavior of the

program, please refer to Figure 2-5.


32/44

6 Installation

32Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


6 Installation

6.1 Hardware installation

The figure below shows the hardware setup of the application.

Figure 6-1

TP700 CPU 1215C IPC 277D

192.168.0.45

Possible Head PLCs

192.168.0.55192.168.0.50

192.168.0.1 192.168.0.2 192.168.0.3 192.168.0.4

CPU 1214C CPU 1212C CPU 1212CCPU 1212C

X208

24V 24V24V

24V24V24V24V

24V

PG

Connect one head PLC (a CPU 1215C or an IPC277D), the field PLCs, theSCALANCE X208 and the panel to one 24V power supply each. Connect all thedevices with a SCALANCE X208 by means of a standard Ethernet cable.

Note The installation guidelines for these components must always be observed.


33/44

6 Installation


C o p y r i g h t S

i e

m e n s A G


6.2 Software installation

Development software

Install the TIA V12 on your configuration computer.

Follow the instructions of the installation program.

Application software

For each head PLC, a sample program is available.

Unpack the zipped code folder 39040038_DATASYNC_CODE_v20.zip from thedownload area into a folder you chose.In this folder, there are the STEP 7 V12 project folders:

DATASYNC_1200 for the S7-1200 CPU as the head PLC.

DATASYNC_IPC for the IPC with WinAC as the head PLC

Navigate to the project folder you need and open the TIA project Datasync.ap12 with a double click.

Figure 6-2


34/44

7 Starting up the Application

34Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G



7.1 Assigning the IP addresses

The following IP addresses are used in this application:

Table 7-1

IP address Component

192.168.0.45 Head PLC S7-1200

192.168.0.55 Head PLC IPC

192.168.0.50 HMI panel

192.168.0.100 PG / PC

192.168.0.1 Field PLC 1

192.168.0.2 Field PLC 2

192.168.0.3 Field PLC 3

192.168.0.4 Field PLC 4

The subnet mask is 255.255.255.0.

PG / PC

Change the IP addresses of the PG / PC as follows:

Table 7-2

No. Action Note

1. For changing the networkaddress, open the Internet log(TCP/IP) settings with “Start >Control Panel > Network andInternet > Network Connections”

Enter the IP address accordingto the figure.

Then close all dialogs with OK.


35/44



C o p y r i g h t S

i e

m e n s A G


SIMATIC components

The SIMATIC components are addressed in the TIA portal by means of the onlinefunction “Assign IP address”.

Table 7-3

No. Action Note

1. Open the portal view of the TIAportal project.

2. First open the tree for the HEADPLC and then double-click onthe function Online &diagnostic.

Note:

If you use the IPC as the headPLC, you use the functionOnline & diagnostic in thesection of the WinAC.

3. In Functions, select Assign IP address.

Click on the button Accessibledevices.


36/44


36Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


No. Action Note

4. If necessary, select the PG / PCinterface. The search foraccessible devices is carried out

automatically.The result is shown in a list.

Identify the PLC you use asHEAD via the MAC address andclick on Apply.

5. Assign the IP address stored inthe project with the commandAssign IP address.

The HEAD PLC now owns the IPaddress stored in the project.

6. Change the IP addresses of thefield PLCs and of the panel in

the same way.


37/44



C o p y r i g h t S

i e

m e n s A G


7.2 Download the PLCs and the panels

In the following, the SIMATIC components with the hardware configuration and the

user program are downloaded.

Note Please find a detailed instruction in the FAQ “How is a project downloaded in theCPU in STEP 7 (TIA portal) V11?” in the Entry ID: 59728694.

Table 7-4

No. Action Note

1. At first, select the first field PLC.

Then download the deviceconfiguration and the program tothe field PLC with the respectivesymbol in Online > Download toDevice.

2. The project is compiled.

Click the “Load” button.

http://support.automation.siemens.com/WW/view/en/59728694http://support.automation.siemens.com/WW/view/en/59728694http://support.automation.siemens.com/WW/view/en/59728694http://support.automation.siemens.com/WW/view/en/59728694http://support.automation.siemens.com/WW/view/en/59728694


38/44


38Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


No. Action Note

3. Activate “Start all” to start theblock.Exit the download with “Finish”.

4. Proceed in the same way for the3 other remaining field PLCs.

Select the stations PLC_2 to

PLC_4 and download therespective field PLC.

5. Select the head PLC.

Note:

When you use the IPC as thehead PLC, select the WinAC.

Then download the deviceconfiguration and the program tothe head PLC with the respectivesymbol in Online > Download toDevice.

The next download procedure is

carried out according to steps 2and 3.


39/44



C o p y r i g h t S

i e

m e n s A G


No. Action Note

6. For transferring the HMI project,select the HMI station in the TIAproject and download it to the

panel with the respective symbolor Online > Download to Device.

The next download procedure iscarried out according to step 2.

Note:

Any warning messagesconcerning the name of theobjects in the visualizationimages can be ignored.


40/44

8 Operating the Application

40Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


8 Operating the ApplicationTo describe the principle of data synchronization clearly, several visualizationimages were created for the panel.

HEAD PLC: This overview serves for entering the positions of the field PLCsand for activating the time synchronization.

Field PLC 1…4: These images display the information transmitted by the fieldPLCs:

– weather data

– production data

– calculated position of the sun

Note The data synchronization is started automatically.

Table 8-1

No. Action Note

1. In the HMI screen HEAD PLC,enter the coordinates of everyfield PLC. With these data, thefield PLCs calculate the currentposition of the sun.

2. With the button ActivateTimeSync, you initiate the timesynchronization with all the fieldPLCs.


41/44

8 Operating the Application


C o p y r i g h t S

i e

m e n s A G


No. Action Note

3. Change to the visualization ofthe field PLCs with thenavigation.

Here, the information isdisplayed which the field PLCstransmit to the head PLC.

4. With the HOME button youchange back to the HEAD PLCoverview screen at any time.

5. With the switch-off symbol, youexit the runtime.


42/44

9 Related literature

42Datasync

V21, Entry ID: 39040038

C o p y r i g h t S

i e

m e n s A G


9 Related literatureThis list is not complete and only represents a selection of relevant literature.

BibliographyTable 9-1

Subject Title

/1/ STEP7

SIMATIC S7-300/400

Automating with STEP7 in STL and SCL

Author: Hans Berger

Publicis MCD Verlag

ISBN: 978-3-89578-397-5

/2/ STEP7

SIMATIC S7-1200

Automating with SIMATIC S7-1200

Author: Hans Berger

Publicis MCD Verlag

ISBN: 978-3-89578-355-5

Internet link specifications

This list is not complete and only represents a selection of relevant information

Table 9-2

Subject Title

/1/ Reference to thedocument

http://support.automation.siemens.com/WW/view/en/39040038

/2/ Siemens IndustryOnline Support

http://support.automation.siemens.com

/3/

10 HistoryTable 10-1

Version Date Modifications

V1.0 10/2009 First version

V2.0 05/2013 Complete review of code and document.

http://support.automation.siemens.com/WW/view/en/39040038http://support.automation.siemens.com/WW/view/en/39040038http://support.automation.siemens.com/http://support.automation.siemens.com/http://support.automation.siemens.com/http://support.automation.siemens.com/WW/view/en/39040038


43/44

11 Appendix A: Measured Data


C o p y r i g h t S

i e

m e n s A G



11.1 Head: S7-1200; 6 ms program load

11.2 Head: S7-1200; 50 ms program load

Number of

substations

Number of bytes 1 in ms 4 in ms 8 in ms 16 in ms 32 in ms 10 min 1637min 1486min 1739min 3313min 6944

max 1834max 4710max 6899max 8053max 12347 average 1740 average 2781 average 3775 average 5131average 8490

100 min 1867min 1740min 1724min 3494min 7202

max 2009max 4793max 6601max 6799max 12598 average 1975average 2805average 3230 average 4977average 8854


max 1857max 4757max 5743max 7205max 12065 average 1721 average 2777average 3158 average 4726average 9226


max 1952max 4645max 5010max 8668max 12709 average 1853 average 2698average 3149 average 5168average 8830

Number of

substations

Number of bytes 1 in ms 4 in ms 8 in ms 16 in ms 32 in ms 10 min 234min 443min 500min 987min 1912

max 323max 3522max 3539max 3009max 5155

average 280 average 741 average 1752 average 2047average 2334











44/44


C o p y r i g h t S

i e

m e n s A G


11.3 Head: WinAC; 6 ms program load

11.4 Head: WinAC; 50 ms program load

Number of

substations

Number of bytes 1 in ms 4 in ms 8 in ms 16 in ms 32 in ms10 min 1694min 1550min 1538min 3124min 6223


average 1704average 1812 average 1972 average 3353 average 7537


max 1741max 2344max 2649max 4321max 10668average 1704average 2070 average 2286 average 3355 average 7416



average 1703 average 2178 average 2428 average 4182 average 7502



average 1707average 2172 average 2566 average 4065 average 7700

Number of

substations

Number of bytes 1 in ms 4 in ms 8 in ms 16 in ms 32 in ms

10 min 198 min 187 min 192 min 385 min 3108

max 219 max 362 max 536 max 643 max 803











39040038 Datasync Doku v21 En

Documents

Transcript of 39040038 Datasync Doku v21 En