Redundancy

WinCC OA redundancy

The PROFIsafe driver can run in one of the following modes:

  • Standalone: The driver runs in a non-redundant WinCC OA project

  • Redu-Standby: The driver runs on the passive host of a redundant project

  • Redu-Active: The driver runs on the active host of a redundant project

For the WinCC OA redundancy, a PROFINET card is necessary for both drivers (on the active and the passive side) to be part of the PROFIsafe network. Both drivers represent independent F-devices in the network which means that an independent configuration and treatment in the user program of the F-PLC (F-host) as well as in WinCC OA is necessary for each driver.

You have to define a mode tag for each driver in order to transmit the driver's current operation mode (redu-active or redu-standby) to the F-host. This tag must be evaluated in the program of the F-PLC. The driver constantly writes the mode tag's value to the process image of the card and immediately updates it on status changes in WinCC OA (i.e. a redundancy switch-over).

PLC program

The PLC (F-host) must be programmed to transmit all signals from / to both PROFIsafe drivers. Therefor, both F-devices (each represented by one driver) must be configured identically. This means that the process image (same order, size and direction of defined transfer areas) and Media-Redundancy-Protocol settings must be identical. Only the safety parameters F-source address and F-destination address must be unique for each F-device and must not be the same.

The PLC program must consider the mode tags defined for the drivers to only react on commands and incoming values originating from the active WinCC OA host. If both drivers present the redu-active mode, the PLC programs considers an error and will not accept any values or commands.

Redundant connection

The Media-Redundancy-Protocol (MRP) handles redundant connections from the PROFINET card to the safety controller. The MRP must be enabled in the TIA Portal. No additional PLC programming or driver configuration is necessary for this functionality. A switch-over of physical connections is automatically executed and cannot be triggered manually or programmatically.