Introduction

The basic idea behind the TwinCAT I/O interface is to grant Windows programs (Windows NT/2000/XP user mode and/or Windows CE application) access to the TwinCAT I/O subsystem without using ADS communication.
Therefore a user mode DLL is supplied which offers a set of interface functions to trigger the fieldbus I/O and to exchange the process data with the TwinCAT I/O subsystem.

The configuration is done in the standard TwinCAT way through the TwinCAT System Manager.

The interface DLL is optimized to access the process images as directly as possible. Through this interface a Windows NT user mode application is able to use all fieldbus types available for the TwinCAT system (Lightbus, Profibus, Interbus, CANOpen, DeviceNet, Ethernet,…).

There is an example for processing fieldbus I/O later in this document.