User`s guide

Introduction
Microsoft Windows 3.1x supports access to DOS drivers through an interface layer
called DOS Protected Mode Interface (DPMI). This interface standard defines the
requirements to switch the processor between protected (Windows) and Real (DOS)
mode operation, and also the mechanisms for proper data transfer between code
running in these operating environments. Using DPMI, the same driver may be used
in DOS, Windows 3.1x, and Windows 95198 without modification.
The DPMI layer that allows access to the LDVSLTA.SYS and other DOS drivers
provided by Echelon is contained in the Windows 3. lx DLL, WLDV.DLL. This DLL is
part of the LonManager@ API for Windows, and the LonManager DDE Server. It is
also supplied on the Windows 3.1x DLL diskette. The LonManager API provides high
level functions for network installation, maintanence, monitoring, and control. The
LonManager DDE Server provides a simple Dynamic Data Exchange (DDE) interface
for other client Windows applications to access to a LONWORKS based network for
monitoring and control.
Programs specify a logical network driver name when first requesting access to the
network. The WLDV.DLL supports simultaneous access to a maximum of eight (8)
DOS drivers. The functions provided by WLDV.DLL are described in the following
section.
A-2
Appendix A