snap ethernet-based i/o units protocols and programming guide

CHAPTER 3: USING THE SNAP ETHERNET I/O DRIVER TOOLKIT
other specific brain models. See page 6 for features that apply to each model. For example, SNAP
Simple I/O does not do high-speed digital counting. Methods such as GetStreamReadArea
normally read and write data on active counters; you can still use these methods for SNAP
Simple I/O, but disregard any data in the areas that don’t apply.
A Note on Multithreading
The components and classes in this toolkit do not have internal synchronization. If you wish to
access a single instance of an object from multiple threads, you must provide your own external
synchronization.
Installing the Driver Toolkit
The SNAP Ethernet I/O Driver Toolkit consists of examples and all source code. It is included on
the CD that came with the brain and is also available from our Web site at www.opto22.com.
Two installations are available:
For Windows, use SnapENETDTK_R20a.exe. It will copy all files and register the ActiveX
components.
If you have difficulty using the toolkit, make sure you have installed OptoEnetUtilities.exe,
which updates certain system files.
For Linux, use snapenetdtk_R20a.tar. It contains just the files needed for a Linux system.
Overview of the ActiveX Components
You can use the OptoSnapIoMemMapX and OptoSnapIoStreamX ActiveX components from
Windows programming environments that support ActiveX components, such as Borland Delphi,
Microsoft Visual Basic®, Visual Basic for Applications, VBScript, and Visual C++. See “Important
ActiveX Client Issues” on page 47 for more details on suitable clients.
ActiveX is an umbrella term for many technologies based on COM (Component Object Model, a
Microsoft technology allowing binary code reuse). Different programming environments use
different terminology; in this chapter, we use terms as follows:
An interface is a set of related functions (not a user interface).
A component is an implementation of one or more interfaces.
A control is a component that also has user interface elements.
An object is an instance of a component.
A type library is a description of a library’s exposed classes, interfaces, methods, and
properties. In this toolkit, the type library is contained in the OptoSnapIoMemMapX.dll file.
46 SNAP Ethernet-Based I/O Units Protocols and Programming Guide