Help Please

vanvanero

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Is it possible to read/write data from a PLC without connecting to it using the libnodave library? If so, how can I accomplish this? I am using one of the test programs that I have running with a s-300 PLC. The reason for this, is that I want to make sure that in the event the connection crashes, that I still have a way to read/write to the PLC. Sort of a fail-safe method. Thank you
 
without a second physical connection? i think this is not possible. if the libnodave library chrashes then this means often the way to the plc is gone. so, a second application with the same physical connection as libnodave uses, will crash also...

instead using the libnodave, especially in a .net enviroment, you can use the s7.net library. there you can also understand in an easy way how the connection and the communication works.
 
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In actuality, my libnodave program doesn't crash. I am only trying to recreate an instance of a crash that I am experiencing in another type of program similar to libnodave. If I can fail-proof the connection in libnodave, I can fail proof the connection in my other program.
 
In actuality, my libnodave program doesn't crash. I am only trying to recreate an instance of a crash that I am experiencing in another type of program similar to libnodave. If I can fail-proof the connection in libnodave, I can fail proof the connection in my other program.

ok, so check out the s7.net http://s7net.codeplex.com/
it make the same like libnodave (connect an application to a free number of PLC) but is written in c# and uses the .net framework
 
...an instance of a crash that I am experiencing in another type of program similar to libnodave. If I can fail-proof the connection in libnodave, I can fail proof the connection in my other program.
Who did program that "other program"? If it's commercial, then there should be support. If you wrote it, you should know it better than you know Libnodave, so you should try to "fail proof" it first.
P.S. Didn't I comment in another thread on "communicate without connection"?
 
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About your requests I am going to to get a Problem.
For you and us it would be helpful to tell what you want to do.

If a connection crashes, there must be a reason why this happens.
If this happens you have to react in your program in the right way.
It makes no sense to have another programm in the back that should continue your communication.

Could you expain what you want to do?


bike
 
I will try to be more straight-forward about what I need to do. As you probably already know, I am a beginner programmer. I go to college and currently, I am working in an internship. My task is to learn libnodave as much as I can. The other part of my task is to use a program and modify it to where it can read and/or write a PLC without being connected. (the current program used to connect PLCs sometimes crashes at the connection, but this program is written in VB) My boss is the person who wrote the VB code that he uses. However, he is not very knowledgeable in C++. I only have one or two basic courses in C++, but am trying to find a way to complete my task. It is very rare for the connection to crash, but we want to make the read and write method safe from ever being interrupted. This is the reason for my question. Again, I don't mean to clutter with my questions, just looking for a little help.

@Zottel, I did see your response at the other thread but was a little confused and looking for a little more detail, hence my other thread.

Thank you
 
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