Data logging in labview table wont proceed to next line
Hi,
I have managed to read the data from Visa read and display to a graph. Now, I need to put it into excel file but the problem is that, it is always on the first line in the excel like table i generated in labview. I hope someone can help. Thanks in advance!
Solved!
Go to Solution.
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Dataloggerv2.vi 32 KB
I tried this. But, it's still not working
Attachments:
Dataloggerv2.vi 32 KB
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Plc data logging using Labview
I am trying to communicate with PACSystem RX3i using Labview in order to log
data from PLC. Is this possible?
If it is possible, how could I implement it?Hi mber,
Thanks for posting at NI forums. I looked into the supported device & driver plug-in list for NI OPC Servers, and the PACSystem RX3i is supported. To configure the OPC server to communicate with this PLC, you can follow the steps given in this article. In the LabVIEW side, you can configure an I/O server as an OPC client to communicate with the server.
In order to configure the I/O server you will require the Datalogging and Supervisory Control (DSC) module installed for LabVIEW. In the article I just referenced, it shows how to configure bound variables to communicate with the PLC tags to retrieve data. The DSC module installs a Citadel database, so when you are configuring the bound variable, you can choose to log data depending on events, alarms or a historical log. This article describes the data logging options using the DSC module. You can also choose to read and display the data in a VI by dragging the bound variables to the block diagram and then log to a file using logging functions.
Best Regards,
Alina M
Applications Engineering
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How to select the data efficiently from the table
hi every one,
i need some help in selecting data from FAGLFLEXA table.i have to select many amounts from different group of G/L accounts
(groups are predefined here which contains a set of g/L account no.).
if i select every time for each group then it will be a performance issue, in order to avoid it what should i do, can any one suggest me a method or a smaple query so that i can perform the task efficiently.Hi ,
1.select and keep the data in internal table
2.avoid select inside loop ..endloop.
3.try to use for all entries
check the below details
Hi Praveen,
Performance Notes
1.Keep the Result Set Small
You should aim to keep the result set small. This reduces both the amount of memory used in the database system and the network load when transferring data to the application server. To reduce the size of your result sets, use the WHERE and HAVING clauses.
Using the WHERE Clause
Whenever you access a database table, you should use a WHERE clause in the corresponding Open SQL statement. Even if a program containing a SELECT statement with no WHERE clause performs well in tests, it may slow down rapidly in your production system, where the data volume increases daily. You should only dispense with the WHERE clause in exceptional cases where you really need the entire contents of the database table every time the statement is executed.
When you use the WHERE clause, the database system optimizes the access and only transfers the required data. You should never transfer unwanted data to the application server and then filter it using ABAP statements.
Using the HAVING Clause
After selecting the required lines in the WHERE clause, the system then processes the GROUP BY clause, if one exists, and summarizes the database lines selected. The HAVING clause allows you to restrict the grouped lines, and in particular, the aggregate expressions, by applying further conditions.
Effect
If you use the WHERE and HAVING clauses correctly:
There are no more physical I/Os in the database than necessary
No unwanted data is stored in the database cache (it could otherwise displace data that is actually required)
The CPU usage of the database host is minimize
The network load is reduced, since only the data that is required by the application is transferred to the application server.
Minimize the Amount of Data Transferred
Data is transferred between the database system and the application server in blocks. Each block is up to 32 KB in size (the precise size depends on your network communication hardware). Administration information is transported in the blocks as well as the data.
To minimize the network load, you should transfer as few blocks as possible. Open SQL allows you to do this as follows:
Restrict the Number of Lines
If you only want to read a certain number of lines in a SELECT statement, use the UP TO <n> ROWS addition in the FROM clause. This tells the database system only to transfer <n> lines back to the application server. This is more efficient than transferring more lines than necessary back to the application server and then discarding them in your ABAP program.
If you expect your WHERE clause to return a large number of duplicate entries, you can use the DISTINCT addition in the SELECT clause.
Restrict the Number of Columns
You should only read the columns from a database table that you actually need in the program. To do this, list the columns in the SELECT clause. Note here that the INTO CORRESPONDING FIELDS addition in the INTO clause is only efficient with large volumes of data, otherwise the runtime required to compare the names is too great. For small amounts of data, use a list of variables in the INTO clause.
Do not use * to select all columns unless you really need them. However, if you list individual columns, you may have to adjust the program if the structure of the database table is changed in the ABAP Dictionary. If you specify the database table dynamically, you must always read all of its columns.
Use Aggregate Functions
If you only want to use data for calculations, it is often more efficient to use the aggregate functions of the SELECT clause than to read the individual entries from the database and perform the calculations in the ABAP program.
Aggregate functions allow you to find out the number of values and find the sum, average, minimum, and maximum values.
Following an aggregate expression, only its result is transferred from the database.
Data Transfer when Changing Table Lines
When you use the UPDATE statement to change lines in the table, you should use the WHERE clause to specify the relevant lines, and then SET statements to change only the required columns.
When you use a work area to overwrite table lines, too much data is often transferred. Furthermore, this method requires an extra SELECT statement to fill the work area. Minimize the Number of Data Transfers
In every Open SQL statement, data is transferred between the application server and the database system. Furthermore, the database system has to construct or reopen the appropriate administration data for each database access. You can therefore minimize the load on the network and the database system by minimizing the number of times you access the database.
Multiple Operations Instead of Single Operations
When you change data using INSERT, UPDATE, and DELETE, use internal tables instead of single entries. If you read data using SELECT, it is worth using multiple operations if you want to process the data more than once, other wise, a simple select loop is more efficient.
Avoid Repeated Access
As a rule you should read a given set of data once only in your program, and using a single access. Avoid accessing the same data more than once (for example, SELECT before an UPDATE).
Avoid Nested SELECT Loops
A simple SELECT loop is a single database access whose result is passed to the ABAP program line by line. Nested SELECT loops mean that the number of accesses in the inner loop is multiplied by the number of accesses in the outer loop. You should therefore only use nested SELECT loops if the selection in the outer loop contains very few lines.
However, using combinations of data from different database tables is more the rule than the exception in the relational data model. You can use the following techniques to avoid nested SELECT statements:
ABAP Dictionary Views
You can define joins between database tables statically and systemwide as views in the ABAP Dictionary. ABAP Dictionary views can be used by all ABAP programs. One of their advantages is that fields that are common to both tables (join fields) are only transferred once from the database to the application server.
Views in the ABAP Dictionary are implemented as inner joins. If the inner table contains no lines that correspond to lines in the outer table, no data is transferred. This is not always the desired result. For example, when you read data from a text table, you want to include lines in the selection even if the corresponding text does not exist in the required language. If you want to include all of the data from the outer table, you can program a left outer join in ABAP.
The links between the tables in the view are created and optimized by the database system. Like database tables, you can buffer views on the application server. The same buffering rules apply to views as to tables. In other words, it is most appropriate for views that you use mostly to read data. This reduces the network load and the amount of physical I/O in the database.
Joins in the FROM Clause
You can read data from more than one database table in a single SELECT statement by using inner or left outer joins in the FROM clause.
The disadvantage of using joins is that redundant data is read from the hierarchically-superior table if there is a 1:N relationship between the outer and inner tables. This can considerably increase the amount of data transferred from the database to the application server. Therefore, when you program a join, you should ensure that the SELECT clause contains a list of only the columns that you really need. Furthermore, joins bypass the table buffer and read directly from the database. For this reason, you should use an ABAP Dictionary view instead of a join if you only want to read the data.
The runtime of a join statement is heavily dependent on the database optimizer, especially when it contains more than two database tables. However, joins are nearly always quicker than using nested SELECT statements.
Subqueries in the WHERE and HAVING Clauses
Another way of accessing more than one database table in the same Open SQL statement is to use subqueries in the WHERE or HAVING clause. The data from a subquery is not transferred to the application server. Instead, it is used to evaluate conditions in the database system. This is a simple and effective way of programming complex database operations.
Using Internal Tables
It is also possible to avoid nested SELECT loops by placing the selection from the outer loop in an internal table and then running the inner selection once only using the FOR ALL ENTRIES addition. This technique stems from the time before joins were allowed in the FROM clause. On the other hand, it does prevent redundant data from being transferred from the database.
Using a Cursor to Read Data
A further method is to decouple the INTO clause from the SELECT statement by opening a cursor using OPEN CURSOR and reading data line by line using FETCH NEXT CURSOR. You must open a new cursor for each nested loop. In this case, you must ensure yourself that the correct lines are read from the database tables in the correct order. This usually requires a foreign key relationship between the database tables, and that they are sorted by the foreign key. Minimize the Search Overhead
You minimize the size of the result set by using the WHERE and HAVING clauses. To increase the efficiency of these clauses, you should formulate them to fit with the database table indexes.
Database Indexes
Indexes speed up data selection from the database. They consist of selected fields of a table, of which a copy is then made in sorted order. If you specify the index fields correctly in a condition in the WHERE or HAVING clause, the system only searches part of the index (index range scan).
The primary index is always created automatically in the R/3 System. It consists of the primary key fields of the database table. This means that for each combination of fields in the index, there is a maximum of one line in the table. This kind of index is also known as UNIQUE.
If you cannot use the primary index to determine the result set because, for example, none of the primary index fields occur in the WHERE or HAVING clause, the system searches through the entire table (full table scan). For this case, you can create secondary indexes, which can restrict the number of table entries searched to form the result set.
You specify the fields of secondary indexes using the ABAP Dictionary. You can also determine whether the index is unique or not. However, you should not create secondary indexes to cover all possible combinations of fields.
Only create one if you select data by fields that are not contained in another index, and the performance is very poor. Furthermore, you should only create secondary indexes for database tables from which you mainly read, since indexes have to be updated each time the database table is changed. As a rule, secondary indexes should not contain more than four fields, and you should not have more than five indexes for a single database table.
If a table has more than five indexes, you run the risk of the optimizer choosing the wrong one for a particular operation. For this reason, you should avoid indexes with overlapping contents.
Secondary indexes should contain columns that you use frequently in a selection, and that are as highly selective as possible. The fewer table entries that can be selected by a certain column, the higher that columns selectivity. Place the most selective fields at the beginning of the index. Your secondary index should be so selective that each index entry corresponds to at most five percent of the table entries. If this is not the case, it is not worth creating the index. You should also avoid creating indexes for fields that are not always filled, where their value is initial for most entries in the table.
If all of the columns in the SELECT clause are contained in the index, the system does not have to search the actual table data after reading from the index. If you have a SELECT clause with very few columns, you can improve performance dramatically by including these columns in a secondary index.
Formulating Conditions for Indexes
You should bear in mind the following when formulating conditions for the WHERE and HAVING clauses so that the system can use a database index and does not have to use a full table scan.
Check for Equality and Link Using AND
The database index search is particularly efficient if you check all index fields for equality (= or EQ) and link the expressions using AND.
Use Positive Conditions
The database system only supports queries that describe the result in positive terms, for example, EQ or LIKE. It does not support negative expressions like NE or NOT LIKE.
If possible, avoid using the NOT operator in the WHERE clause, because it is not supported by database indexes; invert the logical expression instead.
Using OR
The optimizer usually stops working when an OR expression occurs in the condition. This means that the columns checked using OR are not included in the index search. An exception to this are OR expressions at the outside of conditions. You should try to reformulate conditions that apply OR expressions to columns relevant to the index, for example, into an IN condition.
Using Part of the Index
If you construct an index from several columns, the system can still use it even if you only specify a few of the columns in a condition. However, in this case, the sequence of the columns in the index is important. A column can only be used in the index search if all of the columns before it in the index definition have also been specified in the condition.
Checking for Null Values
The IS NULL condition can cause problems with indexes. Some database systems do not store null values in the index structure. Consequently, this field cannot be used in the index.
Avoid Complex Conditions
Avoid complex conditions, since the statements have to be broken down into their individual components by the database system.
Reduce the Database Load
Unlike application servers and presentation servers, there is only one database server in your system. You should therefore aim to reduce the database load as much as possible. You can use the following methods:
Buffer Tables on the Application Server
You can considerably reduce the time required to access data by buffering it in the application server table buffer. Reading a single entry from table T001 can take between 8 and 600 milliseconds, while reading it from the table buffer takes 0.2 - 1 milliseconds.
Whether a table can be buffered or not depends its technical attributes in the ABAP Dictionary. There are three buffering types:
Resident buffering (100%) The first time the table is accessed, its entire contents are loaded in the table buffer.
Generic buffering In this case, you need to specify a generic key (some of the key fields) in the technical settings of the table in the ABAP Dictionary. The table contents are then divided into generic areas. When you access data with one of the generic keys, the whole generic area is loaded into the table buffer. Client-specific tables are often buffered generically by client.
Partial buffering (single entry) Only single entries are read from the database and stored in the table buffer.
When you read from buffered tables, the following happens:
1. An ABAP program requests data from a buffered table.
2. The ABAP processor interprets the Open SQL statement. If the table is defined as a buffered table in the ABAP Dictionary, the ABAP processor checks in the local buffer on the application server to see if the table (or part of it) has already been buffered.
3. If the table has not yet been buffered, the request is passed on to the database. If the data exists in the buffer, it is sent to the program.
4. The database server passes the data to the application server, which places it in the table buffer.
5. The data is passed to the program.
When you change a buffered table, the following happens:
1. The database table is changed and the buffer on the application server is updated. The database interface logs the update statement in the table DDLOG. If the system has more than one application server, the buffer on the other servers is not updated at once.
2. All application servers periodically read the contents of table DDLOG, and delete the corresponding contents from their buffers where necessary. The granularity depends on the buffering type. The table buffers in a distributed system are generally synchronized every 60 seconds (parameter: rsdisp/bufreftime).
3. Within this period, users on non-synchronized application servers will read old data. The data is not recognized as obsolete until the next buffer synchronization. The next time it is accessed, it is re-read from the database.
You should buffer the following types of tables:
Tables that are read very frequently
Tables that are changed very infrequently
Relatively small tables (few lines, few columns, or short columns)
Tables where delayed update is acceptable.
Once you have buffered a table, take care not to use any Open SQL statements that bypass the buffer.
The SELECT statement bypasses the buffer when you use any of the following:
The BYPASSING BUFFER addition in the FROM clause
The DISTINCT addition in the SELECT clause
Aggregate expressions in the SELECT clause
Joins in the FROM clause
The IS NULL condition in the WHERE clause
Subqueries in the WHERE clause
The ORDER BY clause
The GROUP BY clause
The FOR UPDATE addition
Furthermore, all Native SQL statements bypass the buffer.
Avoid Reading Data Repeatedly
If you avoid reading the same data repeatedly, you both reduce the number of database accesses and reduce the load on the database. Furthermore, a "dirty read" may occur with database tables other than Oracle. This means that the second time you read data from a database table, it may be different from the data read the first time. To ensure that the data in your program is consistent, you should read it once only and then store it in an internal table.
Sort Data in Your ABAP Programs
The ORDER BY clause in the SELECT statement is not necessarily optimized by the database system or executed with the correct index. This can result in increased runtime costs. You should only use ORDER BY if the database sort uses the same index with which the table is read. To find out which index the system uses, use SQL Trace in the ABAP Workbench Performance Trace. If the indexes are not the same, it is more efficient to read the data into an internal table or extract and sort it in the ABAP program using the SORT statement.
Use Logical Databases
SAP supplies logical databases for all applications. A logical database is an ABAP program that decouples Open SQL statements from application programs. They are optimized for the best possible database performance. However, it is important that you use the right logical database. The hierarchy of the data you want to read must reflect the structure of the logical database, otherwise, they can have a negative effect on performance. For example, if you want to read data from a table right at the bottom of the hierarchy of the logical database, it has to read at least the key fields of all tables above it in the hierarchy. In this case, it is more efficient to use a SELECT statement.
Work Processes
Work processes execute the individual dialog steps in R/3 applications. The next two sections describe firstly the structure of a work process, and secondly the different types of work process in the R/3 System.
Structure of a Work Process
Work processes execute the dialog steps of application programs. They are components of an application server. The following diagram shows the components of a work process:
Each work process contains two software processors and a database interface.
Screen Processor
In R/3 application programming, there is a difference between user interaction and processing logic. From a programming point of view, user interaction is controlled by screens. As well as the actual input mask, a screen also consists of flow logic. The screen flow logic controls a large part of the user interaction. The R/3 Basis system contains a special language for programming screen flow logic. The screen processor executes the screen flow logic. Via the dispatcher, it takes over the responsibility for communication between the work process and the SAPgui, calls modules in the flow logic, and ensures that the field contents are transferred from the screen to the flow logic.
ABAP Processor
The actual processing logic of an application program is written in ABAP - SAPs own programming language. The ABAP processor executes the processing logic of the application program, and communicates with the database interface. The screen processor tells the ABAP processor which module of the screen flow logic should be processed next. The following screen illustrates the interaction between the screen and the ABAP processors when an application program is running.
Database Interface
The database interface provides the following services:
Establishing and terminating connections between the work process and the database.
Access to database tables
Access to R/3 Repository objects (ABAP programs, screens and so on)
Access to catalog information (ABAP Dictionary)
Controlling transactions (commit and rollback handling)
Table buffer administration on the application server.
The following diagram shows the individual components of the database interface:
The diagram shows that there are two different ways of accessing databases: Open SQL and Native SQL.
Open SQL statements are a subset of Standard SQL that is fully integrated in ABAP. They allow you to access data irrespective of the database system that the R/3 installation is using. Open SQL consists of the Data Manipulation Language (DML) part of Standard SQL; in other words, it allows you to read (SELECT) and change (INSERT, UPDATE, DELETE) data. The tasks of the Data Definition Language (DDL) and Data Control Language (DCL) parts of Standard SQL are performed in the R/3 System by the ABAP Dictionary and the authorization system. These provide a unified range of functions, irrespective of database, and also contain functions beyond those offered by the various database systems.
Open SQL also goes beyond Standard SQL to provide statements that, in conjunction with other ABAP constructions, can simplify or speed up database access. It also allows you to buffer certain tables on the application server, saving excessive database access. In this case, the database interface is responsible for comparing the buffer with the database. Buffers are partly stored in the working memory of the current work process, and partly in the shared memory for all work processes on an application server. Where an R/3 System is distributed across more than one application server, the data in the various buffers is synchronized at set intervals by the buffer management. When buffering the database, you must remember that data in the buffer is not always up to date. For this reason, you should only use the buffer for data which does not often change.
Native SQL is only loosely integrated into ABAP, and allows access to all of the functions contained in the programming interface of the respective database system. Unlike Open SQL statements, Native SQL statements are not checked and converted, but instead are sent directly to the database system. Programs that use Native SQL are specific to the database system for which they were written. R/3 applications contain as little Native SQL as possible. In fact, it is only used in a few Basis components (for example, to create or change table definitions in the ABAP Dictionary).
The database-dependent layer in the diagram serves to hide the differences between database systems from the rest of the database interface. You choose the appropriate layer when you install the Basis system. Thanks to the standardization of SQL, the differences in the syntax of statements are very slight. However, the semantics and behavior of the statements have not been fully standardized, and the differences in these areas can be greater. When you use Native SQL, the function of the database-dependent layer is minimal.
Types of Work Process
Although all work processes contain the components described above, they can still be divided into different types. The type of a work process determines the kind of task for which it is responsible in the application server. It does not specify a particular set of technical attributes. The individual tasks are distributed to the work processes by the dispatcher.
Before you start your R/3 System, you determine how many work processes it will have, and what their types will be. The dispatcher starts the work processes and only assigns them tasks that correspond to their type. This means that you can distribute work process types to optimize the use of the resources on your application servers.
The following diagram shows again the structure of an application server, but this time, includes the various possible work process types:
The various work processes are described briefly below. Other parts of this documentation describe the individual components of the application server and the R/3 System in more detail.
Dialog Work Process
Dialog work processes deal with requests from an active user to execute dialog steps.
Update Work Process
Update work processes execute database update requests. Update requests are part of an SAP LUW that bundle the database operations resulting from the dialog in a database LUW for processing in the background.
Background Work Process
Background work processes process programs that can be executed without user interaction (background jobs).
Enqueue Work Process
The enqueue work process administers a lock table in the shared memory area. The lock table contains the logical database locks for the R/3 System and is an important part of the SAP LUW concept. In an R/3 System, you may only have one lock table. You may therefore also only have one application server with enqueue work processes.
Spool Work Process
The spool work process passes sequential datasets to a printer or to optical archiving. Each application server may contain several spool work process.
The services offered by an application server are determined by the types of its work processes. One application server may, of course, have more than one function. For example, it may be both a dialog server and the enqueue server, if it has several dialog work processes and an enqueue work process.
You can use the system administration functions to switch a work process between dialog and background modes while the system is still running. This allows you, for example, to switch an R/3 System between day and night operation, where you have more dialog than background work processes during the day, and the other way around during the night.
ABAP Application Server
R/3 programs run on application servers. They are an important component of the R/3 System. The following sections describe application servers in more detail.
Structure of an ABAP Application Server
The application layer of an R/3 System is made up of the application servers and the message server. Application programs in an R/3 System are run on application servers. The application servers communicate with the presentation components, the database, and also with each other, using the message server.
The following diagram shows the structure of an application server:
The individual components are:
Work Processes
An application server contains work processes, which are components that can run an application. Work processes are components that are able to execute an application (that is, one dialog step each). Each work process is linked to a memory area containing the context of the application being run. The context contains the current data for the application program. This needs to be available in each dialog step. Further information about the different types of work process is contained later on in this documentation.
Dispatcher
Each application server contains a dispatcher. The dispatcher is the link between the work processes and the users logged onto the application server. Its task is to receive requests for dialog steps from the SAP GUI and direct them to a free work process. In the same way, it directs screen output resulting from the dialog step back to the appropriate user.
Gateway
Each application server contains a gateway. This is the interface for the R/3 communication protocols (RFC, CPI/C). It can communicate with other application servers in the same R/3 System, with other R/3 Systems, with R/2 Systems, or with non-SAP systems.
The application server structure as described here aids the performance and scalability of the entire R/3 System. The fixed number of work processes and dispatching of dialog steps leads to optimal memory use, since it means that certain components and the memory areas of a work process are application-independent and reusable. The fact that the individual work processes work independently makes them suitable for a multi-processor architecture. The methods used in the dispatcher to distribute tasks to work processes are discussed more closely in the section Dispatching Dialog Steps.
Shared Memory
All of the work processes on an application server use a common main memory area called shared memory to save contexts or to buffer constant data locally.
The resources that all work processes use (such as programs and table contents) are contained in shared memory. Memory management in the R/3 System ensures that the work processes always address the correct context, that is the data relevant to the current state of the program that is running. A mapping process projects the required context for a dialog step from shared memory into the address of the relevant work process. This reduces the actual copying to a minimum.
Local buffering of data in the shared memory of the application server reduces the number of database reads required. This reduces access times for application programs considerably. For optimal use of the buffer, you can concentrate individual applications (financial accounting, logistics, human resources) into separate application server groups.
Database Connection
When you start up an R/3 System, each application server registers its work processes with the database layer, and receives a single dedicated channel for each. While the system is running, each work process is a user (client) of the database system (server). You cannot change the work process registration while the system is running. Neither can you reassign a database channel from one work process to another. For this reason, a work process can only make database changes within a single database logical unit of work (LUW). A database LUW is an inseparable sequence of database operations. This has important consequences for the programming model explained below.
Dispatching Dialog Steps
The number of users logged onto an application server is often many times greater than the number of available work processes. Furthermore, it is not restricted by the R/3 system architecture. Furthermore, each user can run several applications at once. The dispatcher has the important task of distributing all dialog steps among the work processes on the application server.
The following diagram is an example of how this might happen:
1. The dispatcher receives the request to execute a dialog step from user 1 and directs it to work process 1, which happens to be free. The work process addresses the context of the application program (in shared memory) and executes the dialog step. It then becomes free again.
2. The dispatcher receives the request to execute a dialog step from user 2 and directs it to work process 1, which is now free again. The work process executes the dialog step as in step 1.
3. While work process 1 is still working, the dispatcher receives a further request from user 1 and directs it to work process 2, which is free.
4. After work processes 1 and 2 have finished processing their dialog steps, the dispatcher receives another request from user 1 and directs it to work process 1, which is free again.
5. While work process 1 is still working, the dispatcher receives a further request from user 2 and directs it to work process 2, which is free.
From this example, we can see that:
A dialog step from a program is assigned to a single work process for execution.
The individual dialog steps of a program can be executed on different work processes, and the program context must be addressed for each new work process.
A work process can execute dialog steps of different programs from different users.
The example does not show that the dispatcher tries to distribute the requests to the work processes such that the same work process is used as often as possible for the successive dialog steps in an application. This is useful, since it saves the program context having to be addressed each time a dialog step is executed.
Dispatching and the Programming Model
The separation of application and presentation layer made it necessary to split up application programs into dialog steps. This, and the fact that dialog steps are dispatched to individual work processes, has had important consequences for the programming model.
As mentioned above, a work process can only make database changes within a single database logical unit of work (LUW). A database LUW is an inseparable sequence of database operations. The contents of the database must be consistent at its beginning and end. The beginning and end of a database LUW are defined by a commit command to the database system (database commit). During a database LUW, that is, between two database commits, the database system itself ensures consistency within the database. In other words, it takes over tasks such as locking database entries while they are being edited, or restoring the old data (rollback) if a step terminates in an error.
A typical SAP application program extends over several screens and the corresponding dialog steps. The user requests database changes on the individual screens that should lead to the database being consistent once the screens have all been processed. However, the individual dialog steps run on different work processes, and a single work process can process dialog steps from other applications. It is clear that two or more independent applications whose dialog steps happen to be processed on the same work process cannot be allowed to work with the same database LUW.
Consequently, a work process must open a separate database LUW for each dialog step. The work process sends a commit command (database commit) to the database at the end of each dialog step in which it makes database changes. These commit commands are called implicit database commits, since they are not explicitly written into the application program.
These implicit database commits mean that a database LUW can be kept open for a maximum of one dialog step. This leads to a considerable reduction in database load, serialization, and deadlocks, and enables a large number of users to use the same system.
However, the question now arises of how this method (1 dialog step = 1 database LUW) can be reconciled with the demand to make commits and rollbacks dependent on the logical flow of the application program instead of the technical distribution of dialog steps. Database update requests that depend on one another form logical units in the program that extend over more than one dialog step. The database changes associated with these logical units must be executed together and must also be able to be undone together.
The SAP programming model contains a series of bundling techniques that allow you to group database updates together in logical units. The section of an R/3 application program that bundles a set of logically-associated database operations is called an SAP LUW. Unlike a database LUW, a SAP LUW includes all of the dialog steps in a logical unit, including the database update.
Happy Reading...
shibu -
How to data log graphs using front panel data logging?
Hello I have a VI that collects data from DAQmx thermocouple readings and graphs the temperature vs time using a while loop to collect data and graph. I have 9 control operators that define the correction factor of the thermocouples.
I want to create a datalogging using the option under Operations>Data Logging
When I retrieve the data the only information that is present are the control operators correction factors that I defined. The graphed data that was created is not retrieved.
Is there a solution to show the graphed data plots that were created on the front panel? They remain unchanged from the last run of the VI or blank if I open the VI without having ran the program.
Thank you.This is expected for the Data Logging in LabVIEW. If you want to record the signla data, use the Write to Measurement File Express VI. Here's a link with a walk-through:
http://www.ni.com/academic/students/learn-daq/data-logging/
The Data Logging from the Operate Menu is for recording front panel control(s), as you have observed.
Mark P.
Applications Engineer
National Instruments
www.ni.com/support -
How to populate data in dynamic internal table
Hi Expert,
fyi. My dynamic internal table field is created base on data selected. Eg. select table qpcd has 5 records. These 5 recods will become fieldname to my dynamic internal table. My dynamic internal table will be
...itab
01
02
03
04
05
The 5 records from qpcd is populated in another table call viqmel. I need to find the occurance of each code in viqmel and populate the number of occurance in itab in each of column. The final dynamic itab will be like this
table itab
01 02 03 04 05 -
> field name
2 0 1 0 1 -
> data
my source code like below
Report ZPLYGRND2.
TABLES: mara, makt.
TYPE-POOLS: slis, sydes.
DATA:it_fcat TYPE slis_t_fieldcat_alv,
is_fcat LIKE LINE OF it_fcat,
ls_layout TYPE slis_layout_alv.
DATA: it_fieldcat TYPE lvc_t_fcat,
is_fieldcat LIKE LINE OF it_fieldcat.
DATA: new_table TYPE REF TO data,
new_line TYPE REF TO data,
ob_cont_alv TYPE REF TO cl_gui_custom_container,
ob_alv TYPE REF TO cl_gui_alv_grid,
vg_campos(255) TYPE c,
i_campos LIKE TABLE OF vg_campos,
vg_campo(30) TYPE c,
vg_tables(60) TYPE c.
types : begin of t_qpcd,
codegruppe like qpcd-codegruppe,
code like qpcd-code,
end of t_qpcd.
data:wa_qpcd type t_qpcd,
i_qpcd type standard table of t_qpcd initial size 0.
FIELD-SYMBOLS: <l_table> TYPE table,
<l_line> TYPE ANY,
<l_field> TYPE ANY.
select * into corresponding fields of wa_qpcd from qpcd
where katalogart = 'D'
and codegruppe = 'OOT01'.
append wa_qpcd to i_qpcd.
endselect.
loop at i_qpcd into wa_qpcd.
is_fcat-fieldname = wa_qpcd-code.
APPEND is_fcat TO it_fcat.
endloop.
LOOP AT it_fcat INTO is_fcat.
is_fieldcat-fieldname = is_fcat-fieldname.
is_fieldcat-ref_field = is_fcat-ref_fieldname.
is_fieldcat-ref_table = is_fcat-ref_tabname.
APPEND is_fieldcat TO it_fieldcat.
ENDLOOP.
*... Create the dynamic internal table
CALL METHOD cl_alv_table_create=>create_dynamic_table
EXPORTING
it_fieldcatalog = it_fieldcat
IMPORTING
ep_table = new_table.
if sy-subrc = 0.
endif.
*... Create a new line
ASSIGN new_table->* TO <l_table>.
CREATE DATA new_line LIKE LINE OF <l_table>.
ASSIGN new_line->* TO <l_line>.
LOOP AT <l_table> INTO <l_line>.
ENDLOOP.hello dear i m giving u a code in this a dynamic table is made on the basis of table in database , and u can download this data correct it , see it, or even change it....and upload in tht table help full if u dont know the table name...in advance.
also the code to populate data in dynamic table is in this code like:
SELECT * FROM (MTABLE_N)
INTO CORRESPONDING FIELDS OF TABLE <FS_ITAB> .
look at the whole program .hope this solve ur problem thanks.
REPORT ZTESTA MESSAGE-ID ZIMM .
TYPES : DATA_OBJECT TYPE REF TO DATA.
DATA : MITAB TYPE REF TO DATA .
TYPE-POOLS : SLIS .
DATA : IT_FIELDCAT TYPE STANDARD TABLE OF SLIS_FIELDCAT_ALV
WITH HEADER LINE .
DATA : IT_FIELDCATALOG TYPE LVC_T_FCAT .
DATA : WA_FIELDCATALOG TYPE LVC_S_FCAT .
DATA : I_STRUCTURE_NAME LIKE DD02L-TABNAME .
DATA : I_CALLBACK_PROGRAM LIKE SY-REPID .
DATA : DYN_LINE TYPE DATA_OBJECT .
FIELD-SYMBOLS : <FS_ITAB> TYPE STANDARD TABLE .
DATA : TABLE_NAME_IS_VALID TYPE C .
DATA : DYNAMIC_IT_INSTANTIATED TYPE C .
CONSTANTS BUTTONSELECTED TYPE C VALUE 'X' .
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 5(29) T_TABL.
PARAMETERS : MTABLE_N LIKE RSRD1-TBMA_VAL
MATCHCODE OBJECT DD_DBTB_16 OBLIGATORY .
DATA CHECKTABLED.
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 5(29) T_FILE.
PARAMETERS : MFILENAM LIKE RLGRAP-FILENAME .
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 5(29) T_DOWN.
PARAMETERS : P_DOWNLD RADIOBUTTON GROUP GRP1
USER-COMMAND M_UCOMM .
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 5(29) T_CHKF.
PARAMETERS : P_CHKFIL RADIOBUTTON GROUP GRP1 .
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 5(29) T_UPLD.
PARAMETERS : P_UPLOAD RADIOBUTTON GROUP GRP1 .
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 5(29) T_SHOW.
PARAMETERS : P_SHOW_T RADIOBUTTON GROUP GRP1 .
SELECTION-SCREEN END OF LINE.
AT SELECTION-SCREEN OUTPUT .
PERFORM CHECK_FILENAME .
AT SELECTION-SCREEN.
IF SY-UCOMM = 'ONLI'.
CHECKTABLED = MTABLE_N+0(1).
IF CHECKTABLED NE 'Z'.
MESSAGE I017.
LEAVE TO SCREEN 1000.
ENDIF.
IF SY-UNAME NE 'KAMESH.K'.
MESSAGE I023 WITH SY-UNAME.
LEAVE TO SCREEN 1000.
ENDIF.
ENDIF.
IF SY-UCOMM = 'PRIN'.
CHECKTABLED = MTABLE_N+0(1).
IF CHECKTABLED NE 'Z'.
MESSAGE I017.
LEAVE TO SCREEN 1000.
ENDIF.
IF SY-UNAME NE 'KAMESH.K'.
MESSAGE I023 WITH SY-UNAME.
LEAVE TO SCREEN 1000.
ENDIF.
ENDIF.
AT SELECTION-SCREEN ON VALUE-REQUEST FOR MFILENAM .
PERFORM F4_FOR_FILENAME .
INITIALIZATION .
T_TABL = 'Table Name' .
T_FILE = 'File Name' .
T_DOWN = 'Download Table' .
T_CHKF = 'Check File to Upload' .
T_UPLD = 'Upload File' .
T_SHOW = 'Show Table Contents' .
START-OF-SELECTION .
PERFORM CHECK_TABLE_NAME_IS_VALID .
END-OF-SELECTION .
IF TABLE_NAME_IS_VALID EQ ' ' .
MESSAGE I398(00) WITH 'INVALID TABLE NAME' .
ELSE .
PERFORM INSTANTIATE_DYNAMIC_INTERNAL_T .
CHECK DYNAMIC_IT_INSTANTIATED = 'X' .
CASE BUTTONSELECTED .
WHEN P_DOWNLD .
PERFORM SELECT_AND_DOWNLOAD .
WHEN P_CHKFIL .
PERFORM CHECK_FILE_TO_UPLOAD .
WHEN P_UPLOAD .
PERFORM UPLOAD_FROM_FILE .
WHEN P_SHOW_T .
PERFORM SHOW_CONTENTS .
ENDCASE .
ENDIF .
FORM CHECK_TABLE_NAME_IS_VALID.
DATA MCOUNT TYPE I .
TABLES DD02L .
CLEAR TABLE_NAME_IS_VALID .
SELECT COUNT(*) INTO MCOUNT FROM TADIR
WHERE PGMID = 'R3TR'
AND OBJECT = 'TABL'
AND OBJ_NAME = MTABLE_N .
IF MCOUNT EQ 1 .
CLEAR DD02L .
SELECT SINGLE * FROM DD02L WHERE TABNAME = MTABLE_N .
IF SY-SUBRC EQ 0.
IF DD02L-TABCLASS = 'TRANSP' .
TABLE_NAME_IS_VALID = 'X' .
ENDIF .
ENDIF.
ENDIF .
ENDFORM. " CHECK_TABLE_NAME_IS_VALID
FORM SELECT_AND_DOWNLOAD.
CLEAR : <FS_ITAB> .
SELECT * FROM (MTABLE_N)
INTO CORRESPONDING FIELDS OF TABLE <FS_ITAB> .
PERFORM CHECK_FILENAME.
CALL FUNCTION 'WS_DOWNLOAD'
EXPORTING
FILENAME = MFILENAM
FILETYPE = 'DAT'
TABLES
DATA_TAB = <FS_ITAB>
EXCEPTIONS
FILE_OPEN_ERROR = 1
FILE_WRITE_ERROR = 2
INVALID_FILESIZE = 3
INVALID_TYPE = 4
NO_BATCH = 5
UNKNOWN_ERROR = 6
INVALID_TABLE_WIDTH = 7
GUI_REFUSE_FILETRANSFER = 8
CUSTOMER_ERROR = 9
OTHERS = 10.
IF SY-SUBRC EQ 0.
MESSAGE I398(00) WITH 'Table' MTABLE_N
'successfully downloaded to '
MFILENAM .
ENDIF.
ENDFORM. " SELECT_AND_DOWNLOAD
FORM UPLOAD_FROM_FILE.
DATA : ANS TYPE C .
DATA : LINES_OF_ITAB TYPE I .
DATA : MSY_SUBRC TYPE I .
CALL FUNCTION 'POPUP_TO_CONFIRM_STEP'
EXPORTING
TEXTLINE1 = 'Are you sure you wish to upload'
TEXTLINE2 = 'data from ASCII File to DB table '
TITEL = 'Confirmation of Data Upload'
IMPORTING
ANSWER = ANS.
IF ANS = 'J' .
PERFORM CHECK_FILENAME.
CLEAR MSY_SUBRC .
CALL FUNCTION 'WS_UPLOAD'
EXPORTING
FILENAME = MFILENAM
FILETYPE = 'DAT'
TABLES
DATA_TAB = <FS_ITAB>
EXCEPTIONS
CONVERSION_ERROR = 1
FILE_OPEN_ERROR = 2
FILE_READ_ERROR = 3
INVALID_TYPE = 4
NO_BATCH = 5
UNKNOWN_ERROR = 6
INVALID_TABLE_WIDTH = 7
GUI_REFUSE_FILETRANSFER = 8
CUSTOMER_ERROR = 9
OTHERS = 10.
MSY_SUBRC = MSY_SUBRC + SY-SUBRC .
IF SY-SUBRC EQ 0.
DESCRIBE TABLE <FS_ITAB> LINES LINES_OF_ITAB .
IF LINES_OF_ITAB GT 0 .
MODIFY (MTABLE_N) FROM TABLE <FS_ITAB> .
MSY_SUBRC = MSY_SUBRC + SY-SUBRC .
ENDIF .
ENDIF.
IF MSY_SUBRC EQ 0 .
MESSAGE I398(00) WITH LINES_OF_ITAB
'Record(s) inserted in table'
MTABLE_N .
ELSE .
MESSAGE I398(00) WITH
'Errors occurred No Records inserted in table'
MTABLE_N .
ENDIF .
ENDIF .
ENDFORM. " UPLOAD_FROM_FILE
FORM F4_FOR_FILENAME.
CALL FUNCTION 'WS_FILENAME_GET'
EXPORTING
DEF_PATH = 'C:\'
MASK = ',.,..'
MODE = '0'
IMPORTING
FILENAME = MFILENAM
EXCEPTIONS
INV_WINSYS = 1
NO_BATCH = 2
SELECTION_CANCEL = 3
SELECTION_ERROR = 4
OTHERS = 5.
ENDFORM. " F4_FOR_FILENAME
FORM CHECK_FILENAME.
IF MFILENAM IS INITIAL
AND NOT ( MTABLE_N IS INITIAL )
AND P_SHOW_T NE BUTTONSELECTED.
CONCATENATE 'C:\'
MTABLE_N '.TXT' INTO MFILENAM.
ENDIF .
ENDFORM. " CHECK_FILENAME
FORM INSTANTIATE_DYNAMIC_INTERNAL_T.
CLEAR DYNAMIC_IT_INSTANTIATED .
I_STRUCTURE_NAME = MTABLE_N .
CLEAR IT_FIELDCAT[] .
CALL FUNCTION 'REUSE_ALV_FIELDCATALOG_MERGE'
EXPORTING
I_STRUCTURE_NAME = I_STRUCTURE_NAME
CHANGING
CT_FIELDCAT = IT_FIELDCAT[]
EXCEPTIONS
INCONSISTENT_INTERFACE = 1
PROGRAM_ERROR = 2
OTHERS = 3.
IF SY-SUBRC EQ 0.
LOOP AT IT_FIELDCAT .
CLEAR WA_FIELDCATALOG .
MOVE-CORRESPONDING IT_FIELDCAT TO WA_FIELDCATALOG .
WA_FIELDCATALOG-REF_FIELD = IT_FIELDCAT-FIELDNAME .
WA_FIELDCATALOG-REF_TABLE = MTABLE_N .
APPEND WA_FIELDCATALOG TO IT_FIELDCATALOG .
ENDLOOP .
CALL METHOD CL_ALV_TABLE_CREATE=>CREATE_DYNAMIC_TABLE
EXPORTING
IT_FIELDCATALOG = IT_FIELDCATALOG
IMPORTING
EP_TABLE = MITAB .
ASSIGN MITAB->* TO <FS_ITAB> .
DYNAMIC_IT_INSTANTIATED = 'X' .
ENDIF.
ENDFORM. " INSTANTIATE_DYNAMIC_INTERNAL_T
FORM SHOW_CONTENTS.
CLEAR : <FS_ITAB> .
SELECT * FROM (MTABLE_N)
INTO CORRESPONDING FIELDS OF TABLE <FS_ITAB> .
I_CALLBACK_PROGRAM = SY-REPID .
CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
EXPORTING
I_CALLBACK_PROGRAM = I_CALLBACK_PROGRAM
IT_FIELDCAT = IT_FIELDCAT[]
TABLES
T_OUTTAB = <FS_ITAB>
EXCEPTIONS
PROGRAM_ERROR = 1
OTHERS = 2.
ENDFORM. " SHOW_CONTENTS
FORM CHECK_FILE_TO_UPLOAD.
PERFORM CHECK_FILENAME.
CALL FUNCTION 'WS_UPLOAD'
EXPORTING
FILENAME = MFILENAM
FILETYPE = 'DAT'
TABLES
DATA_TAB = <FS_ITAB>
EXCEPTIONS
CONVERSION_ERROR = 1
FILE_OPEN_ERROR = 2
FILE_READ_ERROR = 3
INVALID_TYPE = 4
NO_BATCH = 5
UNKNOWN_ERROR = 6
INVALID_TABLE_WIDTH = 7
GUI_REFUSE_FILETRANSFER = 8
CUSTOMER_ERROR = 9
OTHERS = 10.
IF SY-SUBRC EQ 0.
I_CALLBACK_PROGRAM = SY-REPID .
CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
EXPORTING
I_CALLBACK_PROGRAM = I_CALLBACK_PROGRAM
IT_FIELDCAT = IT_FIELDCAT[]
TABLES
T_OUTTAB = <FS_ITAB>
EXCEPTIONS
PROGRAM_ERROR = 1
OTHERS = 2.
ENDIF .
ENDFORM. " CHECK_FILE_TO_UPLOAD
Message was edited by:
SAURABH SINGH
SENIOR EXECUTIVE
SAMSUNG INDIA ELECTRONICS LTD.,NOIDA -
Custom delta extractor: All data deleted in source table in R/3
Hi everyone,
I have made a custom delta extractor from R/3 to a BW system. The setup is the following:
The source table in R/3 holds a timestamp, which is used for the delta. The data is afterwards loaded to a DSO in the BW system. The extractor works as expected with delta capability. Furthermore if I delete a record in the source table, this is not transmitted to the DSO, which is also as expected.
The issue is this however: If we delete all data in the source table, then on the next load there is a request showing 1 record transfered to the DSO. This request does, however, not show up in the PSA, and afterwards all data fields in the DSO is set to initial.
Does anyone know why this happens?
Thank you in advance.
Philip R. JarnhusHi Philip,
As you have used generic extractor I am not sure how the ROCANCEL will work but you can check the below link for more information,
[0RECORDMODE;
Regards,
Durgesh. -
Not getting data into 3rd int table
Hi all,
here i ve data in 2 internal tables. this data i want store into 3rd internal table, here am adding with inner join but am not getting data into 3rd one.
plz check my logic.
REPORT ZEXCHANGE_RETES .
TABLES : tcurr, " Exchange Rates
/msg/rabr. " Account (Posting Headers)
DATA : l_date type datum.
TYPES : begin of t_tcurr,
kurst like tcurr-kurst, " Exchange Rate type
fcurr like tcurr-fcurr, " From Currrency
gdatu like tcurr-gdatu, " Date as of which
end of t_tcurr.
TYPES : begin of t_rabr,
OW_WHGNR like /msg/rabr-OW_WHGNR,
bil_dat like /msg/rabr-bil_dat,
abrnr like /msg/rabr-abrnr,
end of t_rabr.
TYPES : begin of t_output,
kurst like tcurr-kurst,
fcurr like tcurr-fcurr,
gdatu like tcurr-gdatu,
OW_WHGNR like /msg/rabr-OW_WHGNR,
bil_dat like /msg/rabr-bil_dat,
abrnr like /msg/rabr-abrnr,
end of t_output.
DATA : it_output TYPE STANDARD TABLE OF t_output WITH HEADER LINE,
wa_output TYPE t_output.
DATA : it_rabr TYPE STANDARD TABLE OF t_rabr WITH HEADER LINE,
wa_rabr TYPE t_rabr.
DATA : it_tcurr TYPE STANDARD TABLE OF t_tcurr WITH HEADER LINE,
wa_tcurr TYPE t_tcurr.
getting data into 1st itab
SELECT kurst fcurr gdatu
from tcurr into table it_tcurr
where kurst EQ 'M'.
SORT it_tcurr by fcurr GDATU DESCENDING.
delete adjacent duplicates from it_tcurr comparing fcurr.
getting data into 2nd itab
SELECT * FROM /msg/rabr into CORRESPONDING FIELDS OF TABLE it_rabr.
SORT it_rabr BY OW_WHGNR bil_dat abrnr.
getting data into 3rd itab
SELECT t~kurst
t~fcurr
t~gdatu
r~OW_WHGNR
r~bil_dat
r~abrnr
FROM tcurr as t INNER JOIN
/msg/rabr as r on tfcurr EQ rOW_WHGNR into table it_output
WHERE rabrnr BETWEEN '00000000000000800251' AND '00000000000000800300' AND rbil_dat < wa_tcurr-gdatu.
printing output
LOOP at it_output into wa_output.
WRITE: /10 wa_output-kurst,
15 wa_output-fcurr,
25 wa_output-gdatu,
50 wa_output-OW_WHGNR,
60 wa_output-bil_dat,
80 wa_output-abrnr.
ENDLOOP.
here am not getting data into 3rd i tab.
Thanks & Regards,
sudharsan.Hi,
The select command is the most fundamental function of writing ABAP programs allowing the retrieval of data from SAP database tables.
Try filling the 3rd internal table with Loop ... Endloop.
Loop at t_tcurr.
Read table t_rabr with key field1 = t_tcurr-field1.
If sy-subrc = 0.
Move t_tcurr-field1 = itab_final-field1.
Move t_tcurr-field2 = itab_final-field2.
Move t_rabr -field3 = itab_final-field3.
Move t_rabr -field4 = itab_final-field4.
Append itab_final.
Endloop.
Hope this helps you.
Regards,
Ruthra -
Data logging optimization function in LabVIEW and SignalExpress
Hello, everyone! I and a colleague have assembled the attached VI,
which is used to control a plant growth chamber, and I could use some advice.
I would like to add data logging capabilities, ideally to note (1)
environmental conditions, such as temp and CO2 level and (2) when certain
situations occur, such as high CO2 or low pressure (which results in a change
to the “Case Structure for CO2 and Pressure”).
The chamber runs for weeks at a time, though, so I have a constraint.
Instead of continuously logging all the environmental data (which would yield
giant file sizes), I want to be able to take “snapshots”, say every 5 minutes,
so I can examine the chamber’s condition over a long period of time.
I attempted to use the Time Delay function to control the Write Measurements
function (as in LabVIEW’s Cycle Analysis example, which I’ve also attached),
but Time Delay halted my entire program.
I also tried the Wait (ms) function, but had no success.
I recently discovered the powerful data review and reporting tools that
SignalExpress has to offer. Ideally, I
would like to use a SignalExpress express VI to record the measurements instead of the more primative Write Measurements, but, I’m not sure how to implement this in my VI. For example, would I make a data acquisition VI in SignalExpress for all my sensors, export to LabVIEW, and use that to replace the current DAQ structure in my VI? (Because the chamber VI is interactive, I'm pretty sure that porting the LabVIEW VI to SignalExpress wouldn't work out well.) And I’m
still not sure how to control how often it records measurements.
Any advice would be much appreciated!
Attachments:
Chamber VI.vi 789 KB
Cycle Analysis.vi 300 KBHi, Sarah. Yes I definitely plan to use LabVIEW for the majority of my data acquisition and logging. I apologize, I think I probably should have broken my post into two separate posts for clarity, as my major concern is being able to set how often LabVIEW logs the environmental data (viewing the logged data in SignalExpress would be nice, but not a requirement).
As I explained before, I'd really like to be able to set up a system that records the environmental condtions at regular time intervals, say every 30 minutes, or if my "Case Structure for CO2 and Pressure" status changes (such as from "Normal Conditions" to "High CO2".
As an example, attached is a boolean structure (TimedWritedMeasurements.vi) that I came up with to record a simulated signal every 5 seconds (5000 ms). Once I can get it to work, I would connect the boolean to my environmental sensor outputs and CO2 and Pressure case structure in my Chamber VI.vi that I attached in my first post.
My problem is I can't seem to get the Trigger and Gate function to work the way I'd like. I'd like the Wait (ms) function to trigger the Trigger and Gate function every 5 seconds to change the case structure in the TimedWriteMeasurements.vi to "True", thereby causing the Write Measurement function to record the environmental conditions. Then I'd like the case structure reset to false, until it's triggered to true in another five seconds. Can anyone point me in the right direction?
Attachments:
TimedWriteMeasurements.vi 84 KB -
Can any one please tell me how to write labview program for data logging in electric motor bike.
Can any one please tell me how to write labview program for data logging in electric motor bike. I am going to use CompactRIO for getting wide range of data from various sensors in bike. I need to write labview program for data logging of temperature, voltage and speed of the bike. Can any one help me?
Yes, we can.
I think the best place for you to start for this is the NI Developer Zone. I recommend beginning with these tutorials I found by searching on "data log rio". There were more than just these few that might be relevant to your project but I'll leave that for you to decide.
NI Compact RIO Setup and Services -> http://zone.ni.com/devzone/cda/tut/p/id/11394
Getting Started with CompactRIO - Logging Data to Disk -> http://zone.ni.com/devzone/cda/tut/p/id/11198
Getting Started with CompactRIO - Performing Basic Control -> http://zone.ni.com/devzone/cda/tut/p/id/11197
These will probably give you links to more topics/tutorials/examples that can help you design and implement your target system.
Jason
Wire Warrior
Behold the power of LabVIEW as my army of Roomba minions streaks across the floor! -
How can I perform data logging for a specific time??
hello everyone,
I am quite new in labview and I have a basic question regarding data logging. Currently I am using a cRIO9074 and doing some data logging for my test. The data logging it self works ok so far.
But my problem is I would like to write my datas in a text file either for a specific time interval (ex)10 seconds) or for a specific amounts of data (ex)500 Samples). Can anyone give me some help regarding my problem?? Attached you can find my RT.vi
I would appreciate for anyhelp!
Regards
Yun
Attachments:
BP250 Encoder Position & Velocity (Host).vi 92 KBRun your loggging program for that time. When your program terminates then it will write all the logged data so far in text file.
Kudos are always welcome if you got solution to some extent.
I need my difficulties because they are necessary to enjoy my success.
--Ranjeet -
How do I control a data log session with period and sample time?
I need a data logging system where the operator can select 2 logging parameters: Log Period and Sample Time. I also need a START and STOP button to control the logging session. For example, set the log period for 1 hour and the sampling time for 1 second. (I may be using the wrong jargon here.) In this case when the START button is clicked, the system starts logging for 1 second. An hour later, it logs data for another second, and so on until the operator clicks the STOP button. (I will also include a time limit so the logging session will automatically stop after a certain amount of time has elapsed.)
It’s important that when the STOP button is clicked, that the system promptly stops logging. I cannot have the operator wait for up to an hour.
Note that a logging session could last for several days. The application here involves a ship towing a barge at sea where they want to monitor and data log tow line tension. While the system is logging, I need the graph X-axis (autoscaled) to show the date and time. (I’m having trouble getting the graph to show the correct date and time.) For this application, I also need the system to promptly start data logging at a continuous high rate during alarm conditions.
Of course I need to archive the data and retrieve it later for analysis. I think this part I can handle.
Please make a recommendation for program control and provide sample code if you can. It’s the program control concepts that I think I mostly need help here. I also wish to use the Strip Chart Update Mode so the operator can easily view the entire logging session.
DAQ Hardware: Not Selected Yet
LabVIEW Version: 6.1 (Feel free to recommend a v7 solution because I need to soon get it anyway.)
Operating System: Win 2000
In summary:
How do I control a graphing (data log) session for both period and sample time?
How do I stop the session without having to wait for the period to end?
How do I automatically interrupt and control a session during alarm conditions?
Does it make a difference if there is more than one graph (or chart) involved where there are variable sample rates?
Thanks,
DaveHello Dave,
Sounds like you have quite the system to set up here. It doesn�t look like you are doing anything terribly complicated. You should be able to modify different examples for the different parts of your application. Examples are always the best place to start.
For analog input, the �Cont Acq&Chart (buffered).vi� example is a great place to start. You can set the scan rate (scans/second) and how many different input channels you want to acquire. This example has its own stop button; it should be a simple matter to add a manual start button. To manually set how long the application runs, you could add a 100 ms delay to each iteration of the while loop (recommended anyway to allow processor to multi-task) and add a control that sets the number
of iterations of the while loop.
For logging data, a great example is the �Cont Acq to File (binary).vi� example.
For different sample rate for different input lines, you could use two parallel loops both running the first example mentioned above. The data would not be able to be displayed on the same graph, however.
If you have more specific questions about any of the different parts of your application, let me know and I�ll b happy to look further into it.
Have a nice day!
Robert M
Applications Engineer
National Instruments
Robert Mortensen
Software Engineer
National Instruments -
How to input data in a database table without knowing in advance table and column configurations
Hi,
I have a problem using LabVIEW for input data (manually) in a SQL database. I have about 40 tables in the database, each of them is related to a specific engine component. I need to create a user interface (maybe visualizing the table with a table control) where the users can insert data in the database table fields. Could someone give me some suggestion on how to do it?
Using the DB tools insert data.vi I need to know in advance the column configuration of the table, but in my database each table has its own structure! So do I have to create 40 different masks, one for every different table?
Thanks in advance.
MichelaI have not actually used the LV SQL Toolkit, but I will try and offer high level ideas :-)
when you have retrieved the construction data for a table, you should be able to use array and cluster indexing to aquire the names of the fieds, enough to create a labelled table on the LV Front panel.
After completing a new entry you can INSERT the entry into the database using the same data.
Is the SQL toolkit an additional purchase, or included in newer versions as standard? If you post a sample of the cluster/array that you retrieve, I could give you a sample VI to give you some pointers in creating the User Interface table
- Cheers, Ed -
How to load the data from a staging table to interface table
Hi..
I have a staging table having these many columns
invoice_number,invoice_date,vendor_name,vendor_site_code,description,line-amount,line-description,segment1,segment2,segment3,segment4,segment5
I want to insert data into oracle interface tables
1st table is ap_invoices_interface which is primary
and 2nd is ap_invoice_lines_interfaces.
According to the invoice_id I have to insert the sum of amount in the amount column of primary table
can anyone plz give the codes .
any help appreciateHi,
you need to write pl/sql procedure or package for validiating the data and inserting.
first u need to know wat r the mandatory colums. and write the code igiving here a simple example
Create or replace procedure xxstg_po_vendors_int(errbuf out varchar2,retcode out number) IS
Cursor po_cur IS Select sno,VENDOR_NAME,SUMMARY_FLAG,ENABLED_FLAG From xxstg_po_vendor;
l_SUMMARY_FLAG Varchar(1);
l_ENABLED_FLAG varchar(1);
l_VENDOR_NAME varchar2(240);
l_err_msg varchar2(240);
l_flag varchar2(2);
l_err_flag varchar2(2);
Begin
Delete from Ap_suppliers_INT;
commit;
for rec_cur in po_cur loop
l_flag :='A';
l_err_flag:= 'A';
Begin
select summary_flag into l_SUMMARY_FLAG from po_vendors
where summary_flag = rec_cur.summary_flag;
Exception
when others then
l_summary_flag:= null;
l_flag:='E';
l_err_msg:= 'Summary_flag Does not Exist';
END;
FND_FILe.PUT_LINE(FND_FILE.LOG,'Inserting data into interface table'||l_flag);
Begin
Select enabled_flag into l_enabled_flag from po_vendors
where enabled_flag = rec_cur.enabled_flag;
exception
when others then
l_enabled_flag:=null;
l_flag :='E';
L_err_msg:='Enabled_flag Does not Exist';
End;
FND_FILE.PUT_LINE(FND_FILE.log,'Inserting data into interface table'||l_flag);
FND_FILE.PUT_LINE(FND_FILE.log,'Inserting data into interface table'||l_flag);
INSERT INTO AP_SUPPLIERS_INT
( VENDOR_INTERFACE_ID,VENDOR_NAME,SUMMARY_FLAG,ENABLED_FLAG )
values(rec_cur.sno,rec_cur.VENDOR_NAME,rec_cur.SUMMARY_FLAG,rec_cur.ENABLED_FLAG);
l_flag :=null;
l_err_msg:=null;
end loop;
commit;
end;
Regards
Goutham -
How to find out when data was deleted from table in oracle and Who deleted that
HI Experts,
Help me for below query:
how to find out when data was deleted from table in oracle and Who deleted that ?
I did that to fidn out some data from dba_tab_modifications, but I m not sure that what timestamp shows, wether it shows for update,insert or delete time ?
SQL> select TABLE_OWNER,TABLE_NAME,INSERTS,UPDATES,DELETES,TIMESTAMP,DROP_SEGMENTS,TRUNCATED from dba_tab_modifications where TABLE_NAME='F9001';
TABLE_OWNER TABLE_NAME INSERTS UPDATES DELETES TIMESTAMP DROP_SEGMENTS TRU
PRODCTL F9001 1683 46 2171 11-12-13 18:23:39 0 NO
Audit is enable in my enviroment?
customer is facing the issue and data missing in the table and I told him that yes there is a delete at 11-12-13 18:23:39 in table after seeing the DELETS column and timestamp in dba_tab_modifications, but not sure I am right or not
SQL> show parameter audit
NAME TYPE VALUE
audit_file_dest string /oracle/admin/pbowe/adump
audit_sys_operations boolean TRUE
audit_syslog_level string
audit_trail string DB, EXTENDED
please help
Thanks
SamLOGMiner --> Using LogMiner to Analyze Redo Log Files
AUDIT --> Configuring and Administering Auditing -
I am trying to import data characters from a tab delimited file into a table in labview. After I import the strings, I want to be able to select individual strings from the table and put into another table. I want the item that I am selecting to appear in a text box labeled 'selected step'. After I put all of the selected data in the new table, I want to be able to save that table in another tab delimited file (spreadsheet). This is what I have so far. Any help given will be GREATLY appreciated.
Attachments:
Selector.zip 30 KBHi,
Here are modifications to your vi to do what you are describing. It helps, when trying to work through issues like these on this forum to not start a new thread with each iteration of your question. Those of us that are trying to help can follow it better if you just "Reply" to your previous thread with the new, related question. If the question is for a totally new issue then a new thread is best, but when you are working through the details of essentially the same problem it really helps us follow it if you stay in one thread, and that usually means faster answers.
We also like it if, when an answer helps, you give us a rating (the more stars the better) as it is about all we get out of it!
P.M.
Putnam
Certified LabVIEW Developer
Senior Test Engineer
Currently using LV 6.1-LabVIEW 2012, RT8.5
LabVIEW Champion
Attachments:
SelectorV2.zip 30 KB
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