Installation manual

REDUNDANT SYSTEMS
39
6
6 REDUNDANT SYSTEMS
6.1 GENERAL DESCRIPTION
The REDS function replicates the SC6000 controller, PWO power supply, presence sensor
and encoder devices. The scanner network is not replicated as it already implements a form
of redundancy.
6.1.1 Basic Concepts
REDS is based on the following:
The redundant station can be logically seen as the combination of two separate stand-
alone stations connected through a “redundancy cable” (Lonworks + serial). The
redundancy cable connects the two Lonworks network halves and allows controller-to-
controller communication to exchange data that will be used to supervise and manage
the role the controllers play in the system.
The companion controllers run the same software and configuration, except for one
parameter that assigns their topology role (Working/Protecting).
The supported operating mode is “PackTrack”.
The scanner network is fully managed by the Active controller. At initialization time the
scanners are informed about which controller they have to communicate with.
Both controllers distribute their own encoder to all the controlled scanners, however the
scanners only use the encoder from the Active controller and only send their data to it.
The scanner replacement is always managed by the Active controller.
6.1.2 System Components
Controller
Two controllers are present in the Lonworks network. One of them acts as an Active unit and
the other as a Standby. In the event of failure, of either the active unit or of its local resources
(presence sensor, encoder), or of Parcel error count conditions, a Standby-Active “switch
over” is performed that guarantees system service after a short off-duty interval.
Lonworks Network
A single Lonworks network (split into two halves) is present that interconnects all the
scanners to both the controllers. The network is fully managed by the active controller.
Presence Sensor and Encoder
Each controller has its own presence sensor and encoder. The scanners use the active
controller’s encoder signal. No presence sensor signal is used by the scanners (only
PackTrack mode is supported).
Redundancy Cable
A dedicated cable (Lonworks + Serial) is used both to interconnect the two halves of the
Lonworks network and exchange redundancy data.