6. REDUNDANCY WITH NX3030 CPU
ATTENTION
When the Active PLC goes out from the Run mode and goes to Not-Configured, if the other
PLC was forgotten in Stand-by state, it takes over as Active and switches off the PLC which
has just gone from Active to Not-Configured. In this case, thus, the offline download can’t
be completed because the PLC connected to MasterTool is off.
When the offline download finishes, it’s possible to restart the PLC program execution where the application was down-
loaded (put in Run again). After a few seconds, this PLC takes over again the Active state.
After this PLC takes the Active state again, the other PLC can go out from the Inactive state, e.g. pressing the PX2612
STAND-BY button on it. This causes the transition of this PLC to the Not-Configured state. This PLC remains in the Not-
Configured state until the automatic project synchronization finishes. Then, it goes to Starting state and back to Stand-by state
afterwards.
6.5.7. Previous Planning for Offline Modifications without Process Control Interruption
The following subsection – Previous Planning for Hot Modifications in Redundant PROFIBUS Networks – describes a very
important procedure which allows the offline modifications download without interrupting the process control. Even though
this procedure doesn’t apply to any modification that demand offline download, it applies to the most used modifications.
However, in order to apply this procedure, the projects must be developed with a previous planning, especially for modifi-
cation that affects the PROFIBUS network. The following subsections describe such previous planning for modifications that
affect the PROFIBUS network and also other modifications.
6.5.7.1. Previous Planning for Hot Modifications in Redundant PROFIBUS Networks
Among the modifications that affect a PROFIBUS network and demand an offline download, the following are supported
by the procedure which allows executing offline downloads without interrupt the process control, if the PROFIBUS network is
redundant:
Insert a new PROFIBUS network
Insert a new Ponto Series remote
Insert a new I/O module in a Ponto Series remote
Modify parameters in Ponto Series remotes or in I/O modules in Ponto Series remotes
ATTENTION
It’s possible to insert non-redundant remotes under a redundant PROFIBUS network, us-
ing the AL-2433 module (ProfiSwitch), as the example shown on Figure 164. However,
such non-redundant remotes will suffer discontinuities (output deactivation) when the of-
fline download is executed.
Next, the planning steps that must start at the creation of a new redundant PROFIBUS network are described.
6.5.7.1.1. Step 1 – Plan Future Expansion of the Remotes Inserted in the PROFIBUS Network Initial Version
At first, a list must be made of the I/O modules which compose each redundant PROFIBUS remote from the Ponto Series,
in the PROFIBUS network initial version. The list must have the position where each I/O module is inserted in the remote
rack.
Next, the future expansion of each remote must be planned. For that, a complementary list must be made, consisting in I/O
modules which might be inserted in the future. In it, the position where each I/O module might be inserted in the remote rack
must be listed.
ATTENTION
At the physical construction of these remotes (electric panels), it’s strongly recommended to
insert compatible bases with the future I/O modules in the respective positions. This way,
when the I/O module insertion is necessary in this remote, there’s no need for switching
off the remote to insert the base. In case this detail isn’t observed, it will be necessary to
switch off the specific remote, as it’s not possible a base hot insertion in the remote. It can
be observed that the remote stopping in some cases can be tolerable, but not always.
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