ETHWAY Service

Introduction

The ETHWAY profile offers the following data exchange capabilities:

data exchanges synchronized on the MAST task
or data exchanges in:
- asynchronous server mode
- asynchronous client mode
or common data exchanges (common words)

Common data exchanges are described below. For a description of synchronous and asynchronous exchanges, see UNI-TE on TCP/IP.

Common Words

All common words represent a database distributed among all or part of the devices on the same network.

The maximum number of common words on a network depends on the number of stations issuing common words:

4 common words per station for 64 active stations
8 common words per station for 32 active stations
16 common words per station for 16 active stations
32 common words per station for 8 active stations
64 common words per station for 4 active stations

NOTE: Common words can take up a large part of the module's messaging bandwidth if there are many stations connected and if the configured PLC cycle time is very short. Common words are issued:

on each PLC cycle if there are changes in status
every 10 cycles if their value is not changed

You must not exceed the maximum capacity of the module.

Common words (%NW) are updated automatically. The application program simply involves writing or reading these words. For example:

%NW1.7.0:= %MW10 (writing a value for sending)
%MW50:=%NW1.8.2 (receiving a value)