User manual

Hot Standby
316
33002479 06 07/2008
NOE Operating Modes and Modicon Quantum Hot Standby with Unity
The NOE Modes The NOE module modes are:
z Primary CPU Mode
The Hot Standby state is primary CPU, and all client/server services are active.
z Secondary Mode
The Hot Standby state is standby, and all server services are active except
DHCP.
z Standalone Mode
The NOE is in a non-redundant system, or the HE CPU module is not present or
is not healthy.
z Offline Mode
The CPU is stopped.
The Modicon Quantum Hot Standby with Unity and the NOE operating modes are
synchronized by the conditions described in the following table:
Any 1 of 4 events will affect the NOE operating mode. These 4 events occur when:
z the NOE is powered up
z an NOE executes a Hot Standby switch over
z an NOE goes to offline mode
z a new application is downloaded to the NOE
HE CPU Module Status HSBY State NOE Operating Mode
Present and Healthy Primary CPU Primary CPU
Present and Healthy Standby CPU Secondary
Present and Healthy Offline Offline
Present and Healthy Unassigned Standalone
Not present or unhealthy N/A Standalone