OPC UA (RealOpcUaClient):
- Append 5 new SelectClauses at indices 13–17 (never renumber 0–12):
- 13: AlarmConditionType/ActiveState/TransitionTime → OriginalRaiseTime
- 14–17: LimitAlarmType HighHighLimit/HighLimit/LowLimit/LowLowLimit → LimitValue
- New OpcUaAlarmMapper.PickLimitValue helper: first non-null in HiHi→Hi→Lo→LoLo
priority order, InvariantCulture-formatted; empty string for non-limit alarm types.
- HandleAlarmEvent reads new indices with fields.Count > N guards; hard minimum (6)
unchanged so base ConditionType events still process without the limit fields.
- Document unavailable-by-protocol fields (Category, Description, OperatorUser,
CurrentValue) inline in BuildAlarmEventFilter and HandleAlarmEvent.
MxGateway (MxGatewayAlarmMapper):
- MapTransition: CurrentValue and LimitValue now populated via MxValueToString
(uses MxValueExtensions.ToClrValue + InvariantCulture) from OnAlarmTransitionEvent
proto fields current_value/limit_value.
- MapSnapshot: same — populated from ActiveAlarmSnapshot.current_value/limit_value.
- MxValueToString helper (internal): null-safe MxValue → string conversion.
Tests (17 new, 40 total pass):
- OpcUaAlarmMapperTests: PickLimitValue priority, InvariantCulture, all-null case.
- MxGatewayAlarmMapperTests: CurrentValue/LimitValue populate from double/string
MxValue; absent fields yield empty strings.
- RealOpcUaClientAlarmFilterTests: index alignment assertions (count=18, per-index
TypeDefinitionId+BrowsePath), regression guard on existing indices 0–12.
Adds IAlarmSubscribableConnection to MxGatewayDataConnection (shared session-less
feed, ref-counted), IMxGatewayClient.RunAlarmStreamAsync over the package
StreamAlarmsAsync with internal reconnect, and MxGatewayAlarmMapper
(AlarmFeedMessage/OnAlarmTransitionEvent -> NativeAlarmTransition). Behavior
verified against a live gateway in Task 28; mapper unit-tested.
Joseph Doherty