Installation manual

BHS AND REDS INSTALLATION MANUAL
50
6
6.4.2 Master Protecting Controller
Starting from the Default, complete the Protecting Controller configuration as follows:
1. Load the Configuration of the Working Controller from the PC.
2. Change only the parameter: > Redundancy Parameters> Topology Redundancy Role
= Master Protecting.
3. Send the configuration to the Protecting Controller: Send with Options + Environmental
Parameters.
6.5 REDUNDANCY SYSTEM FUNCTIONING
6.5.1 Diagnostic Procedures
The messages exchanged by the controllers over the redundancy cable are of two different
types:
Notification of the redundancy role
Diagnostic status (presence sensor and encoder status)
Notifications are used both at initialization time and runtime (cyclic notifications).
Diagnostic status exchange (cyclic) conveys diagnostic data and is used only by the Standby
controller to validate the status of the active controller.
In order to enhance system reliability, in the event the response to the diagnostic polling is
missing over the serial channel, the request is redirected to the Lonworks network.
Startup
The initial status is determined from a lookup table that summarizes the description of all the
possible startup scenarios. The status assigned at startup depends on the assigned topology
role, redundancy role notifications, status of each controller at the moment of the role
negotiation (startup, initialization, runtime).
If the controllers are rebooted, the role negotiation algorithm has no memory of the role each
controller played before being powered down.
Runtime
During normal operations the controllers cyclically exchange data over the redundancy cable
(cyclic role notifications, cyclic encoder and presence sensor diagnostics).
The Standby controller compares its own presence sensor and encoder diagnostics to
validate the role of the Active controller.
Also the Active controller monitors the status of the Standby controller in order to raise an
alarm that alerts about the unavailability of the back up system.
Switch Over
The decision to switch over is taken by the Standby controller when it is sure that taking over
improves the overall performance of the whole system.