ALTUS Nexto NX3004 User Manual

6. Redundancy with NX3030 CPU
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 After this, the Half-Cluster that was in Stand-by will pass to Non-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.
Exploring the Redundancy for Off-Line downloading of Modifications without Interruption of
the Process control
In the Off-Line and On-Line Modifications Download section, it was informed that some
modifications demand an off-line download in the PLC.
In these cases the user has the option to interrupt the process control, according to the procedure
defined in the Off-Line Download of Modifications with Process Control Interruption section. For
that, usually it’s necessary to previously program a process stopping, what isn’t always possible at
the moment the modification is needed.
Fortunately, the PLCs redundancy, and in some cases, the PROFIBUS network redundancy make
possible to execute the off-line download without interrupting the process control, for most of the
modifications needed. For reaching this objective it’s necessary to follow carefully a procedure,
which the steps are described in the following sub-sections.
Step 1 – Verify Basic Requirements Attending
For the off-line 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 Off-Line 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:
o New remotes insertion
o 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
o 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:
o DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.bRedDataSync = TRUE, indicates the
success of the Redundant Data Synchronization service
o DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.bRedForceSync = TRUE, indicates
the success of the Redundant Forcing List service
o DG_NX4010.tRedundancy.RedDgnLoc.sGeneral_Diag.dwApplicationCRC =
DG_NX4010.tRedundancy.RedDgnRem.dwApplicationCRC, indicates both PLCs projects
are equal
Step 2 – Don’t Download in Group Modifications which can be downloaded On-Line
Modifications which can be downloaded on-line must not be downloaded together with modifications
which must be downloaded off-line 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.

ALTUS Nexto NX3004 Specifications

General

Brand	ALTUS
Model	Nexto NX3004
Category	Processor
Language	English