Limitation of connection InTouch -> SQL ?

Hi all !

I'm working on an InTouch V9.5 application which has now 2 connections with a MS SQL data base (I mean using SQLConnect...)

I have to make some modifications on this application and want to add a lot of connections.

Do you know if it's possible to make a lot of different connections ? (50... 100 connections)
Is it OK for InTouch or it will really slow down the system ??

Thanks for answers !!

Why do you need so many connections? Do you have 50 - 100 different databases to connect to? You only need to create new connections when there is a possibility that two or more SQL statements (SQLInsert, SQLSelect, etc.) could be using the same connection ID simultaneously. Essentially, you could use a single connection ID for all your SQL statements as long as a.)your statements reference the same database, and b.)the statements are not executed simultaneously as mentioned above.

Good practice is to open your SQL connections in your application startup script and close them on your application shutdown script. This ensures they are open and available while the application is running and you are not consuming lots of resources creating a connection each time you run a SQL statement.

Jeff

I need so many connections because I have to make a lot of "process" running simultaneously.
In fact, for this part of application, I use InTouch as an interface between SQL and a PLC, not as a simple viewer.
InTouch has to read data in SQL and write it to PLC for 50...100 "objects". and it has to be done simultaneously (asynchronously to be exact). So I have to have one available connection for each "object".

So, creating so much different connections seems not be a good solution, isnt' it ?

I guess I don't understand why you would need to access a SQL database at such a high rate unless the data for the objects were being updated at a high rate by some other source. It almost sounds like you're trying to build your own version of Wonderware's Industrial Application server. For the time, effort, and headaches that will be involved in this process, it would seem justifiable to just buy the license and enjoy all the benefits of the Archestra framework. But that's just my opinion.

And to answer your question, I don't think creating all those connections is a good idea.

No...
Basically, I have some groups of machines which are controlled by a PLC and 2 main tasks have to be done :

1) "download" some parameters (recipes) from SQL to PLC, using InTouch.

2) "upload" some process values (LOG) from PLC to SQL, using InTouch.

And the system is already existing, I cannot change the architecture.

So... Then I have to limit the number of connection to SQL.

Thanks !

How often(transactions/hr) will you need to perform those tasks? In my experience, downloading recipe parameters is something that takes place very infrequently(1-3 times per shift). I would suspect a higher rate for the data logging.

Logs will be performed approx. every 10 seconds.

And the recipes have to be checked (if changes) approx. every 10 or 20 seconds..

But i think i will connect/disconnect each time I make an SQL action...

Thanks for the answers !