6. REDUNDANCY WITH NX3030 CPU
6.5.8.2. Step 2 – Don’t Download in Group Modifications which can be downloaded Online
Modifications which can be downloaded online must not be downloaded together with modifications which must be down-
loaded offline without the process control interruption. When these two kinds of modifications are needed, they must always
be loaded separately.
For the current procedure to be successful, it’s absolutely necessary the modifications executed to don’t cause any changes
in the structure of the redundant variables exchanged between the Active and Non-Active PLC, through the Redundant Data
Synchronization and Redundant Forcing List services. These two services must continue to working properly even while there
are temporary differences between the PLCs. The modifications that must be loaded offline, and supported by this procedure
do not affect the structure of redundant variables.
However, some modifications which can be loaded online can change the structure of redundant variables, e.g.:
Insertion of symbolic variables (redundant or not) within a POU or GVL existing or in a new POU or GVL
Removal of symbolic variables (redundant or not) within a POU or within existing GVL. The removal of a POU or GVL
can also involve the removal of symbolic variables
Change in size/structure of symbolic variables (redundant or not) in an existing POU or GVL
6.5.8.3. Step 3 – Previous Project Backup
Before editing the modifications that must be loaded offline without interrupting the process control, for safety reasons a
backup of the project previous version must be run. It may be necessary to reinstall the previous version in case an error is
committed during this procedure executing.
ATTENTION
The backup recommendation for all loaded versions in the PLCs may not be followed only
in this specific procedure. It must be an usual practice.
6.5.8.4. Step 4 – Cares in Editing the Offline Downloaded Modifications
The offline downloaded modifications through this procedure, usually, are the following:
Insertion of new devices in the devices tree
Property or parameter change in devices existing in the devices tree
Such devices are normally the following:
Modules such as PROFIBUS master (NX5001) or Ethernet modules (NX5000)
Ponto Series PROFIBUS remotes
I/O modules inside Ponto Series PROFIBUS remotes
MODBUS communication I/O drivers
Mapping of MODBUS communication drivers
The following cares must be taken at editing these project modifications:
If a device existed in the previous project version, and continues existing in the modified version, the %I and %Q
variables allocated for it must remain the same (command, diagnostic, inputs and outputs). Care must be taken for the
inserted modifications don’t change such allocations
If a device was inserted in the modified project version, the %I and %Q variables allocated for it must not be allocated
in the previous project version (command, diagnostic, inputs and outputs)
6.5.8.5. Step 5 – Inactive PLC Project Synchronism Disabling
In the procedures described in the Online Download of Modifications and Offline Download of Modifications with Process
Control Interruption sections, the project is automatically synchronized from the Active PLC to the Non-Active PLC.
However, during the procedure of offline downloading without process control interruption, the project synchronism must
be temporarily disabled. The Project synchronization disabling is explained in the section Project Synchronization Disabling
and must be executed in the Non-Active PLC.
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