In the last tutorial, we configured the connection between TwinCAT and MongoDB. This time, we will use the TF6420 Library to access MongoDB data.

Let’s start!

Reference Link

Mongodb#Let’s install Mongodb in your Pi4

MongoDB#Install in Ubuntu

MongoDB#Basic Operation

Beckhoff#TwinCAT3 Let’ use Tc3_JsonXml

Beckhoff#TwinCAT3 TF6420 x MongoDB_Part1

Function Block

This section introduces the Function Block used in this article.

FB_NoSQLQueryBuilder_DocumentDB

Function Block for defining a query on a DateBase; the Query is sent in FB_NoSQLQueryEvt, so there is no need to call the Build Method directly.

VAR_INPUT

Name	Type	Descirption
eQueryType	E_DocumentDbQueryType	Type of query submitted to the database.
sCollectionName	T_ MAXSTRING	Name of Collections to be Queried
pQueryOptions	POINTER TO BYTE	Specifies the Pointer address of the QueryOptions.
cbQueryOptionsr	UDINT	Size of QueryOptions

E_DocumentDBQueryType

{attribute ‘qualified_only’}
TYPE E_DocumentDbQueryType :
(
InsertOne := 1,
InsertMany := 2,
UpdateOne := 3,
UpdateMany := 4 ,
Find := 5,
Aggregation := 6,
Delete := 7,
DeleteMany := 8,
CreateCollection := 9,
DropCollection := 10
);
END_TYPE

T_QueryOptionDocumentDB_Insert

TYPE T_QueryOptionDocumentDB_Insert
STRUCT
pDocuments: POINTER TO BYTE;
cbDocuments: UDINT;
END_STRUCT
END_TYPE

Name	Type	pDocuments
pDocuments	POINTER TO BYTE	Specify the address of the Documents variable to be added to Collections.
cbDocuments	UDINT	Data size of Documents variable.

FB_NoSQLQueryEvt

Function Block for executing a NoSQL Database Query, used by entering it in the Method of the QueryBuilder Function Block.

VAR_INPUT

Name	Type	Descirption
sNetID	T_AmsNetID	AMS Network ID, leave it Empty if Local
tTimeout	TIME	Time setting before the FB is canceled for execution.

VAR_OUTPUTS

Name	Type	Descirption
bBusy	BOOL	1 = FB is running
bError	BOOL	1 = FB has an error.
ipTcResult	Tc3_EventLogger.I_TcMessage	TwinCAT 3 EventLogger Interface for displaying FB execution results in Message.

Properties:eTraceLevel

Name	Type	Access	Descirption
eTraceLevel	TcEventSeverity	Get, Set	1=FB specifies the Severity of the events being performed. Only events with a weighting higher than this value are sent to the TwinCAT system. Specifies the importance of the Event. Only events with a Severity higher than this value are sent to the TwinCAT System.

METHODS:Execute

A Method to send the Query created in QueryBuilderFB to the Database.

METHOD Execute : BOOL
VAR_INPUT
hDBID: UDINT;
iNoSQLQueryBuilder: I_NoSQLQueryBuilder;
END_VAR

VAR_INPUT

Name	Type	Descirption
hDBID	UDINT	ID of the database setting configured.
iNoSSQLQueryBuilder	I_NoSQLQueryBuilder	QueryBuilder FB.

Return Value

Name	Type	Descirption
Execute	Bool	Method execution result; True=Method execution successful.

METHODS:ExecuteDataReturn

The Query created in QueryBuilderFB is sent to the Database; FB_NoSqlResultEvt is passed to read the Data Record returned from the Database.

METHOD ExecuteDataReturn : BOOL
VAR_INPUT
hDBID : UDINT;
iNoSSQLQueryBuilder: I_NoSQLQueryBuilder;
pNoSQLResult: POINTER TO FB_NoSQLResultEvt;
END_VAR

VAR_INPUT

Name	Type	Descirption
hDBID	UDINT	ID of the database setting configured.
iNoSSQLQueryBuilder	I_NoSQLQueryBuilder	QueryBuilder FB.
pNoSQLResult	POINTER TO FB_NoSSQLResultEvt	Instance Pointer in FB_NoSQLResultEvt, used to read Methods results

Return Value

Name	Type	Descirption
ExecuteDataReturn	BOOL	Method execution result: True=Method execution success.
nDataCount	UDINT	Number of records returned

FB_NoSQLResultEvt

When the ExecuteDataReturn Method is called on a FB to read a buffered record, you must first retrieve the Data Record from the Database using FB_NoSQLQueryEvt. FB_NoSQLResultEvt. Once initialized, it can be read back as a PLC structure or a string.

VAR_INPUTS

Name	Type	Descirption
sNetID	T_AmsNetID	AMS Network ID, leave it Empty if Local
tTimeout	TIME	Time setting before the FB is canceled for execution.

VAR_OUTPUTS

Name	Type	Descirption
bBusy	BOOL	1 = FB is running
bError	BOOL	1 = FB has an error.
ipTcResult	Tc3_EventLogger.I_TcMessage	TwinCAT 3 EventLogger Interface for displaying FB execution results in Message.

Properties:eTraceLevel

Name	Type	Descirption
eTraceLevel	TcEventSeverity	1=FB specifies the Severity of the events being performed. Only events with a weighting higher than this value are sent to the TwinCAT system. Specifies the importance of the Event. Only events with a Severity higher than this value are sent to the TwinCAT System.

Properties:nDataCount

Name	Type	Descirption
nDataCount	UDINT	Number of Data Records retrieved from Database

Methods:ReadAsString

This method reads a specified number of Records from data cached in the TwinCAT Database Server and specifies an array of strings from which this data is copied as JSON.

VAR_INPUTS

Name	Type	Descirption
nStartIndex	UDINT	Index of the first Record to be read.
nRecordCount	UDINT	Number of Records to be read.
pData	POINTER TO BYTE	Address of TwinCAT Runtime string array to which Record is written Offset
cbData	UDINT	Size of the TwinCAT Runtime string array to which the Record is written.
nMaxDocumentSize	UDINT	Maximum size of JSON document taken from pData.
bDataRelease	BOOL	Delete cached data.

Return Value

Name	Type	Descirption
ReadAsString	BOOL	Method execution result: True=Method execution success.

Method:ReadAsStruct

This method can read a specified number of records from the buffered result data and store them in a TwinCAT Runtime structure or array of structures; the Validation function of the Function Block can detect and react to data deviations.

VAR_INPUTS

Name	Type	Descirption
nStartIndex	UDINT	Index of the first Record to be read.
nRecordCount	UDINT	Number of Records to be read.
pData	POINTER TO BYTE	Address of TwinCAT Runtime string array to which Record is written Offset
cbData	UDINT	Size of the TwinCAT Runtime string array to which the Record is written.
bValidate	BOOL	The returned data is compared with the pData structure array or adjusted as required.
pNoSQLValidation	POINTER TO FB_NoSQLValidationEvt	Address of the Function Block FB_NoSQLValidationEvt that provides the information to be validated.
nMaxDocumentSize	UDINT	Maximum size of JSON document taken from pData.
bDataRelease	BOOL	Delete cached data.

Return Value

Name	Type	Descirption
ReadAsStruct	BOOL	Method execution result: True=Method execution success.

METHOD:Release

This method can be used to release data cached by the TwinCAT Database Server.

Return Value

Name	Type	Descirption
Release	BOOL	Method execution result: True=Method execution success.

FB_NoSQLValidationEvt

This is a Function Block for reading the validation events and results generated when reading data in FB_NoSQLResultEvt. This Function Block is initialized in the CreateValidation method of NoSQLResult and finally refers to a call to the ReadAsStruct method.

VAR_INPUTS

Name	Type	Descirption
sNetID	T_AmsNetID	AMS Network ID, leave it Empty if Local
tTimeout	TIME	Time setting before the FB is canceled for execution.

VAR_OUTPUTS

Name	Type	Descirption
bBusy	BOOL	1 = FB is running
bError	BOOL	1 = FB has an error.
ipTcResult	Tc3_EventLogger.I_TcMessage	TwinCAT 3 EventLogger Interface for displaying FB execution results in Message.

Properties:eTraceLevel

Name	Type	Access	Descirption
eTraceLevel	TcEventSeverity	Get, Set	1=FB specifies the Severity of the events being performed. Only events with a weighting higher than this value are sent to the TwinCAT system. Specifies the importance of the Event. Only events with a Severity higher than this value are sent to the TwinCAT System.

Methods:GetIssues

Reads the validation events raised by the Function Block into an array of type T_MAXSTRING.

VAR_INPUTS

Name	Type	Descirption
pData	POINTER TO BYTE	Address of TwinCAT Runtime string array to which Record is written Offset
cbData	UDINT	Size of the TwinCAT Runtime string array to which the Record is written.
bDataRelease	BOOL	Delete cached data.

Return Value

Name	Type	Descirption
GetIssues	BOOL	Method execution result: True=Method execution success.

Methods:GetRemainingData

This method can be used to read the remaining data in JSON format after validation.

VAR_INPUTS

Name	Type	Descirption
pData	POINTER TO BYTE	Address of TwinCAT Runtime string array to which Record is written Offset
cbData	UDINT	Size of the TwinCAT Runtime string array to which the Record is written.
cbDocument	UDINT	Document array size
bDataRelease	BOOL	Delete cached data.

Return Value

Name	Type	Descirption
GetRemainingData	BOOL	Method execution result: True=Method execution success.

METHOD:Release

This method can be used to release data cached by the TwinCAT Database Server.

Return Value

Name	Type	Descirption
Release	BOOL	Method execution result: True=Method execution success.

Implementation

We will now use TwinCAT’s TF6420 Library to access MongoDB data.

Flow

Here is the Flow.

DUT

This is the structure of the Query data to be sent to MongoDB in the program.

ST_SubStrucure

TYPE ST_SubStrucure :
STRUCT
Speed:LREAL;
Position:LREAL;
ErrorCode:LINT;
END_STRUCT
END_TYPE

ST_MainStructure

TYPE ST_MainStructure :
STRUCT
Sensor1:LREAL;
r32Array:ARRAY[0..2]OF LREAL;
iArray:ARRAY[0..8]OF DINT;
MotorData:ST_SubStrucure;
END_STRUCT
END_TYPE

Program

This is the program.

PROGRAM MAIN

VAR
fbJson : FB_JsonSaxWriter;
jsonDoc :SJsonValue;
sJsonDoc :STRING(2000);
sDocument : STRING(2000);
END_VAR

VAR

nDBID: INT := 1;
sNetID : STRING := ”;

tTimer4SendQuery :TIME:=T#1S;
TONReflesh :TON;
r32SensorData :LREAL:=0.0;
bError:BOOL;
iStep:INT:=0;
iCount:INT:=0;
ArrayStuctureData : ARRAY [0..999] OF ST_MainStructure;
END_VAR

VAR

//NoSQLFunctionBlock
fbNoSQLQueryBuilder_DocumentDB: FB_NoSQLQueryBuilder_DocumentDB;
fbNoSQLQuery: FB_NoSQLQueryEvt(sNetID := sNetID, tTimeout := TIME#15S0MS);
fbNoSQLResult: FB_NoSQLResultEvt(sNetID := sNetID, tTimeout := TIME#15S0MS);
fbNoSqlValidation : FB_NoSQLValidationEvt(sNetID := sNetID, tTimeout := TIME#15S0MS);
//Optiotns
InsertQueryOptions: T_QueryOptionDocumentDB_Insert;
AggregationQueryOptions: T_QueryOptionDocumentDB_Aggregate;
//Others

InfoResult: I_TcMessage;
sPipeStages : STRING(1000);
END_VAR

CASE iStep OF

0:
InsertQueryOptions.pDocuments:= ADR(sDocument);
InsertQueryOptions.cbDocuments:= SIZEOF(sDocument);
fbNoSQLQueryBuilder_DocumentDB.eQueryType := E_DocumentDbQueryType.InsertOne;
fbNoSQLQueryBuilder_DocumentDB.sCollectionName := ‘myCollection22’;
fbNoSQLQueryBuilder_DocumentDB.pQueryOptions := ADR(InsertQueryOptions);
fbNoSQLQueryBuilder_DocumentDB.cbQueryOptions := SIZEOF(InsertQueryOptions);
iStep:=10;
bError:=FALSE;
10:
//
fbJson.StartObject();
r32SensorData:=r32SensorData+0.01;
IF r32SensorData > 99999.9 THEN
r32SensorData:=0.0;
END_IF
fbJson.AddKeyLreal(key:=’Sensor1′,value:=r32SensorData);

fbJson.AddKey(‘r32Array’);
fbJson.StartArray();
fbJson.AddRawArray(‘123.1,444.5,512.3’);
fbJson.EndArray();

fbJson.AddKey(‘iArray’);
fbJson.StartArray();
fbJson.AddRawArray(‘123,1,5,6,7,8,9,0,111’);
fbJson.EndArray();

fbJson.AddKey(‘MotorData’);
fbJson.StartObject();
fbJson.AddKeyLreal(key:=’Speed’,value:=567.12334);
fbJson.AddKeyLreal(key:=’Position’,value:=450.42);
fbJson.AddKeyNumber(key:=’ErrorCode’,value:=9872);

fbJson.EndObject();

fbJson.EndObject();

sJsonDoc := fbJson.GetDocument();
fbJson.ResetDocument();
iStep:=20;

20:
sDocument:=sJsonDoc;
IF fbNoSQLQuery.Execute(nDBID, fbNoSQLQueryBuilder_DocumentDB) THEN
IF fbNoSQLQuery.bError THEN
InfoResult := fbNoSQLQuery.ipTcResult;
bError:=TRUE;
iStep:=998;
ELSE
IF NOT fbNoSQLQuery.bBusy THEN
iStep:=30;
END_IF;
END_IF
END_IF

30:
AggregationQueryOptions.pPipeStages := ADR(sPipeStages);
AggregationQueryOptions.cbPipeStages := SIZEOF(sPipeStages);
fbNoSQLQueryBuilder_DocumentDB.eQueryType := E_DocumentDbQueryType.Aggregation;
fbNoSQLQueryBuilder_DocumentDB.sCollectionName := ‘myCollection22’;
fbNoSQLQueryBuilder_DocumentDB.pQueryOptions := ADR(AggregationQueryOptions);
fbNoSQLQueryBuilder_DocumentDB.cbQueryOptions := SIZEOF(AggregationQueryOptions);

sPipeStages :='{$$match :{}}’;

IF fbNoSQLQuery.ExecuteDataReturn(nDBID, fbNoSQLQueryBuilder_DocumentDB, pNoSqlResult:= ADR(fbNoSQLResult)) THEN
IF fbNoSQLQuery.bError THEN
InfoResult := fbNoSQLQuery.ipTcResult;
bError:=TRUE;
iStep:=997;
ELSE
iStep:=40;
END_IF
END_IF

40:
IF fbNoSQLResult.ReadAsStruct(1, 10, ADR(ArrayStuctureData), SIZEOF(ArrayStuctureData), bValidate := TRUE, ADR(fbNoSqlValidation), bDataRelease:= TRUE) THEN
IF fbNoSQLResult.bError THEN
InfoResult := fbNoSQLResult.ipTcResult;
bError:=TRUE;
ELSE
iStep:=50;
END_IF
END_IF
50:
TONReflesh(IN:=TRUE,pt:=tTimer4SendQuery);
IF TONReflesh.Q THEN
TONReflesh(IN:=FALSE);
iCount:=iCount+1;
iStep:=0;
END_IF

END_CASE

Result

Done!A new Collections called MyCollections22 has been created.

From Mongo

You can use this command to get the latest data from the MongoDB Shell.

db.myCollection22.find().sort({$natural:-1}).limit(10)

Done!You saw the data issued by TwinCAT.

> db.myCollection22.find().sort({$natural:-1}).limit(10)
{ “_id” : ObjectId(“64aa662bbfe68217dc626f99”), “Sensor1” : 14.549999999999734, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6629bfe68217dc626f98”), “Sensor1” : 14.539999999999734, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6628bfe68217dc626f97”), “Sensor1” : 14.529999999999735, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6627bfe68217dc626f96”), “Sensor1” : 14.519999999999735, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6625bfe68217dc626f95”), “Sensor1” : 14.509999999999735, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6624bfe68217dc626f94”), “Sensor1” : 14.499999999999735, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6623bfe68217dc626f93”), “Sensor1” : 14.489999999999736, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6622bfe68217dc626f92”), “Sensor1” : 14.479999999999736, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa6620bfe68217dc626f91”), “Sensor1” : 14.469999999999736, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }
{ “_id” : ObjectId(“64aa661fbfe68217dc626f90”), “Sensor1” : 14.459999999999736, “r32Array” : [ 123.1, 444.5, 512.3 ], “iArray” : [ 123, 1, 5, 6, 7, 8, 9, 0, 111 ], “MotorData” : { “Speed” : 567.12334, “Position” : 450.42, “ErrorCode” : 9872 } }