Requirements

Two PCs are necessary for SCADA logic redundancy. The both PCs are connected via Ethernet TCP/IP (100MBit, recommended 1GBit).

Attention

The SCADA logic redundancy demands that both systems, zenon and straton, are installed on one PC.

We recommend to set the cycle time of the straton project to twice the cycle time of a single project, but at least to 50 ms.

Since SCADA logic implies that straton and zenon communicate with each other using the shared memory driver (straton to zenonRT connection), it must be guaranteed that the zenon server and the active straton Runtime run on the same PC.

In order to prevent a one-sided switching from straton or zenon, a synchronization between the straton Runtime and the zenon Runtime must be engineered.

For this we recommend the use of a watchdog. This watchdog is implemented in straton as a counter incremented (counted up by one) with each cycle. This counter is allocated to a second variable in zenon. In the straton application the change of this second variable has to be checked in each cycle. If the variable does not change in n cycles, either the redundancy switch in straton (function block:ActiveRTSwitch) is executed or straton is closed (fuction: terminate).
On the side of zenon the change of the watchdog should be checked with a VBA script, which then executes a redundancy switch of the zenon Runtime or closes it.

Attention

The start of the zenon Runtime must not be performed from the zenon Editor but with a direct call from the zenon Runtime!

The zenon redundancy must be set up. Details: See help chapter Network.