ALTUS Nexto NX3004 User Manual

6. Redundancy with NX3030 CPU
290
Sometimes, the CPU goes to Not-Configured state when has already received an automatic
configuration request, when the new request for Starting state changing is not necessary. This
happens at the CPU energizing, for instance.
In other situations, the user must request manually this configuration, e.g. pressing a button on the
PX2612 redundancy command panel. Manually configuration requests typically aren’t necessary
when a user maintenance is needed before going out from the Not-Configured state, e.g. if the CPU
hasn’t reached the Not-Configured state due to some failure.
After getting out from the Not-Configured state, the PLC can go back to this state, due to events such
as:
 Restarting (reset warm, cold or origin)
 PLC switch off
 Different projects between this PLC and the Active PLC
Starting State
Different from all other 4 states which can last indefinitely, the Starting state is temporary, taking
only a few seconds. This state is always reached from the Not-Configured state, through a
configuration request.
At the beginning of the Starting state, several actions, tests and verifications are executed, in order to
decide which will be the next state:
 PROFIBUS masters are enabled in a passive state. The passive mode is used to test the
transmission and reception PROFIBUS circuits and the physical layer, to avoid an occult failure
to happen;
 Verify if the CPU identification is correct (must be PLCA or PLCB);
 Verify if there are problems in the configuration parameters extracted from MasterTool project;
 Verify the NX4010 module integrity;
 The cyclic synchronization services are executed (see Cyclic Synchronization Services through
NETA and NETB section), if the conditions for its execution are true;
 Verify the firmware compatibility version between both CPUs;
 Verify if the projects from both CPUs are equal, if the project automatic synchronization is
enabled (see Project Synchronization Disabling section).
 In case the other CPU is in Active state, verify the possibility to establish a passive PROFIBUS
communication with it. The passive mode is used to test the transmission and reception
PROFIBUS circuits and the physical layer, to avoid an occult failure to happen;
 In case the other CPU is in unknown state due to failures in NETA and NETB, verify the
possibility of establishing a passive PROFIBUS communication with it. If there is no
PROFIBUS network in the project and it neither has the PX2612 Panel, check if CPU’s
NET1/NET2 are receiving Keep Alive packages from the other half-cluster.
Depending on the results of these verifications and tests, the CPU can go from the Starting state to
any from the other four states.
Active State
In this state, the CPU controls the automated process, using the ActivePrg program, executed only in
this state. The Active CPU also updates the PROFIBUS remote I/O system, putting its PROFIBUS
masters in active state. The active state is used to establish communication with the PROFIBUS
remotes (slaves).
The Active CPU also verifies its internal diagnostic and user switchover requests to determine if a
switchover is necessary. The CPU goes out from the Active state only if it knows the other CPU is in
Stand-by mode, and able to assume as Active.
However, there are some situations where the Active CPU could go out from the Active state even
with no certainty that the other CPU is in Stand-by state (e.g. if the CPU is switched off).

ALTUS Nexto NX3004 Specifications

General

Brand	ALTUS
Model	Nexto NX3004
Category	Processor
Language	English