ADS interface

The TwinCAT SMS Server is a software driver that can send SMS messages over a connected GSM modem. For this reason, it makes a Beckhoff ADS (Automation Device Specification) interface available to other communication partners (e.g. the PLC or Visual Basic programs). The use of the ADS standardizes access to the TwinCAT SMS device, placing it in the group of available virtual field devices.

The READ and WRITE operations to and from the interface are implemented, as specified by ADS, using two numbers: the index group and the index offset.
A more detailed description of the group and offset indexes in relation to the SMS Server's ADS interface is given on the following pages.

Specifications of the PLC's "Index Group"

The two global areas of an ADS device are represented for the SMS Server in the index groups as follows: