Configuring Software Redundancy

New Functions in Version V4.02

The configuration of a ªwarm standbyº system consists of:

Two S7 stations with one PROFIBUS-DP master interface each (each of these interfaces forms its own subnet).

One or more ET 200M devices with IM 153-3 which are connected to both subnets.

This configuration ensures that the ªstandby stationº takes over the processing of the user program if one station (one of the two DP masters fails) fails.

Two stations, each with one PROFIBUS-DP master interface

Station A	Station B
	ET 200 M with IM 153-3
DP Master 1	DP Master 2
PROFIBUS

To set up this configuration with STEP 7, proceed as follows:

1.Configure the first station (station A) with all the ET 200M devices (IM 153-3).

2.Configure the second station (station B) without I/Os.

3.Copy the ET 200M in station A and paste these DP slaves in the DP master system of station B (menu command Edit Redundant Paste); see also Page 4 (Improved Copy Function).

In contrast to the ªnormalº Paste function, ªRedundant Pasteº preserves the existing PROFIBUS and I/O addresses. Inconsistencies in addresses are thus avoided. You should follow step 3 very carefully; if the addresses overlap, this may cause the ªRedundant Pasteº to fail.

4.Complete the configuration of station B with central and distributed I/Os.

Important: The DP slaves with IM 153-3 must be configured in each of the two stations, which means they appear as two separate objects, although they are physically one and the same slave. If you change settings for one of the DP slaves, you must also copy this modified DP slave to the other station again to ensure consistency.

8	Supplement to the STEP 7 User Manual V4.0
	C79000-Z7076-C552-01