I need a long term solution for interfacing various equipment to my applications in such way that the main program will not be changed (at least in short term) but the equipment interfaces can change/added upon needs. The typical equipment are generally (but not limited to);
- Image grabber boards or network cameras
- Serial communication based data transmission equipment
- RFID readers (ETH or Serial connected)
- Hardware I/O devices (relay output, signal input) that works on serial ports
- PLC interfaces
Each equipment provider has its own rules and methods to communicate with their devices.
My main reason for the needed solution is;
- I have many main applications that are registered by a certain authority and making changes to the applications is not easy because I have to register the software everytime I change the software and this costs too much.
- I have many equipment options doing similar functions (with performance and cost difference). The preference of equipment is depended on how the system will be applied and even the communication protocols of the equipment are developing continuously.
One solution is developing a COM based solution, for example, a DLL library for each group of equipment. Each compiled DLL will obey to same library documentation but will communicate with its own equipment. The related DLL will be installed to related system. In this way followings are possible;
- The main applications can be registered and distributed regardless of what the equipment is
- A DLL for each newcoming or changed equipment can be prepared and installed upon need
I have some limitations for using ordinary DLL because of the nature of the equipment; I need the interface must stay in memory and stay working because I need to make work timers and events because;
- The equipment sends it message anytime, an awake thread will need to capture it (such as serial or TCP/IP socket)
- The data need to be made ready before it is asked by the library using application (such as pooling data from more than one resource)
- There are timings required by equipment protocols
- Some initializations takes time (such as serial/Socket/board/Camera etc.) and not possible to initialize it anytime before a data poll.
I was using ActiveX Exe previously (VB6) for this purpose, and that was a real "miracle solution" for the problem. But the ActiveX Exe is not supported by VB.NET. VB6 ActiveX Exe still can be used by VB.NET applications by Object creation methods but VB6 is getting obsolete both by Microsoft and also by equipment providers interface support.
Is there any long term technology that can be used for this purpose, i.e. directly replace to behaviour of "ActiveX Executable".
The target OS is Windows XP/Vista/7 Clients or Windows Server platforms (2003/2008) in 32 or 64 bit modes.
Thanks in Advance...