6. REDUNDANCY WITH NX3030 CPU
Disable the Project Synchronization through the Online/Redundancy Configuration menu
Download the updated Project into the Half-Cluster that’s in Stand-by state. A message will be displayed indicating the
PersistentVars object memory area reorganization. The procedure must continue and by the end of the project download
the Half-Cluster will remain in STOP with a redundancy state as Not-Configured
Put the CPU in RUN. The Half-Cluster will change to Starting state and then to Stand-by. The Half-Cluster will syn-
chronize its data with the one that’s in Active state
The data from the PersistentVars object must be copied from the Active Half-Cluster to the Stand-by manually or the
receipt resource must be used
Put the Active Half-Cluster to Stand-by. With this action, the other Half-Cluster will go to Active
Enable the Project Synchronization through the Online/Redundancy Configuration menu. After this, the Half-Cluster in
Stand-by state will go into Not-Configured state and will receive the project from the Half-Cluster in Active state. By
the end of this process, the Half-Cluster state will go to Starting and then back to Stand-by
Change the Project of the Half-Cluster in Active state marking the PersistentVars object inside the Redundancy Config-
uration object. This download must be done as an Online change, and for this to happen, another change in the project
must be done, e.g. removing the variable declared at the beginning of this process
After this, the Half-Cluster that was in Stand-by will pass to Not-Configured and will receive the Project from the
Half-Cluster in Active state. By the end of this process the Half-Cluster state will change to Starting and then back to
Stand-by
6.5.8. Exploring the Redundancy for Offline downloading of Modifications without Interruption of the Process control
In the section Offline and Online Modifications Download, it was informed that some modifications demand offline load-
ing in the PLC where such modifications must be loaded. In these cases, the user has the option to interrupt the process control,
according to the procedure defined in the section Offline Download of Modifications with Process Control Interruption. There-
fore, it is usually necessary to program a process stop in advance, which is not always possible when an urgent modification is
needed.
Thanks to the redundancy of the PLCs and, in some cases, thanks to the redundancy of the PROFIBUS network, it is
possible to carry out offline loads without interrupting the process control for most of the usually necessary modifications. To
achieve this goal, it is necessary to carefully follow a procedure, whose steps are described in the following subsections.
6.5.8.1. Step 1 – Verify Basic Requirements Attending
For the offline downloading with no interruption of the process control to be possible, the following basic requirements
must be attended:
The original project must have been created according to the recommendations of the Previous Planning for Offline
Modifications without Process Control Interruption section
The PLC must be redundant
In case the modification affects the PROFIBUS network, it’s necessary this network to be redundant. Such modifications
may be:
• New remotes insertion
• I/O modules insertion in existent remotes, in previously reserved positions for correspondent virtual modules. For
the remote not have to be switched off, there’s the need of a base compatible with the new I/O module in the
position reserved for it
• Parameters modifications in remotes or existent I/O modules
Both PLCs projects must be equalized and the Redundant Data Synchronization and Redundant Forcing List services
must be working properly with no failure diagnostics. It can be stated these conditions are satisfied when there’s a PLC in
Active state and another in Stand-by state. In case the Non-Active PLC isn’t in Stand-by state, the following diagnostics
can be observed:
• DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.bRedDataSync = TRUE, indicates the success of the Re-
dundant Data Synchronization service
• DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.bRedForceSync = TRUE, indicates the success of the Re-
dundant Forcing List service
• DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.dwApplicationCRC = DG_NX4010.tRedundancy.RedDgnRem
.dwApplicationCRC, indicates both PLCs projects are equal
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