User guide

C
-
Bus OPC installation
User Guide
20
© Schneider Electric 2011
Event and alarm conditions
The OPC Server receives Error Reporting messages from C-Bus, then
processes them as OPC events that may change alarm condition states.
The OPC Server also processes OPC acknowledgment messages from the
OPC Client. The OPC events and alarm conditions are defined below:
Events
An event condition represents a change of state for an error condition of
an output unit channel. For example, an error condition can be the
overheating of an Architectural dimmer channel. If an Architectural
dimmer channel begins to overheat, there is a change of state of the error
condition from inactive to active. If the event is configured to be sent to
OPC Clients, then the C-Bus OPC Server will pass it on with an associated
severity level that ha been configured between 1 (minimum severity) and
1000 (maximum severity).
Alarm conditions
An alarm condition reflects the current stat of an error condition. It also
has an associated severity level that has been configured between 1
(minimum severity) and 1000 (maximum severity), and a possible
requirement for acknowledgement by an OPC Client.
Alarm condition states
If an alarm condition has been configured not to require
acknowledgement, it has two states: inactive and active. When an event is
received from an output unit channel that has a different state, the alarm
condition state will be updated internally and broadcast to the OPC
Clients.
If an error condition has been configured to require acknowledgement, it
has four states:
 inactive, acknowledged
 active, acknowledged
 active, unacknowledged
 and inactive, unacknowledged.
Change of states are always associated with a message. The state machine
exists as part of the C-Bus OPC Server. The OPC Server maintains the
status of error conditions by receiving Error Reporting messages from C-
Gate for updating data from the C-Bus units and alarm
acknowledgements from the OPC Client.
When an event is received from an output unit channel that has a
different active state, the alarm condition state will be updated internally
according to a state machine and broadcast to the OPC Clients. If the
acknowledged state is unacknowledged and an OPC Client acknowledges
the alarm condition, the state will be updated internally according to a
state machine and broadcast to the OPC Clients. The state diagram
(below) shows the OPC Alarms and Events states for managing error
conditions.