u90ladder.dll specs

[cautbaia]

Hello everyone.I am very new to plc programming and i stumbled upon a problem that i can't manage to work out. I work in a cinema as a projectionist and the entire booth is automated through a CAN network through consisting of 7 plcs. We control the projectors with the help of a program written by someone who never provided no specs about it and since it offers little flexibility we are in need of figuring out how the dynamic link library on which the program is built , actually works. I tried communicating through a set of Win32 api (c++) functions but it doesn't seem to work. I made a dump on the u90ladder.dll and can see that there is a whole interface in the format U90COM_func but searching on the internet i just can't find any documentation avalable. I am to write a program that extends the functionality of the already available one and i need some tips on how to use the u90ladder.dll api or the win32 api for serial communications , if it conforms to the standards of course.Lots of thanks to everyone and i hope someone can sprinkle a bit of clarity upon me.

[Emil]

What exactly you want ot program? M90/91 itself or PC to communicate with it?

If it's the PLC:

U90Ladder is a programming environment by itself. you don't need to work with a part of it. The programming language is Ladder diagram.

If you want to communicate with PC:

In Unitronics web site www.unitronics.com > Support page > Downloads > PC to PLC communication tools you can find some DLL and .NET driver, winch I hope will be useful.

[cautbaia]

Sorry for replying after such a long time .I had given up then since i couldn't find any resource but now i'm at it again so the question is: Is there an API with function calls for building a program to communicate with the PLC?I know there are dynamic link libraries containing such functions but there is no documentation anywhere .. Help me out please and thanks