Codec-encoded scalars ("True", "42.5") reached RealOpcUaClient.WriteValuesAsync
as strings and were sent as String Variants, so a Boolean/Double node answered
BadTypeMismatch (0x80740000).
RealOpcUaClient now reads each written node's DataType attribute once per
session (batched, cached, cleared on connect/disconnect; derived types and
enumerations resolved via the supertype chain) and converts non-null scalar
values with the new OpcUaWriteCoercion table: Boolean, SByte..UInt64, Float,
Double, String, DateTime, Guid, all culture-invariant. Overflow, fractional
values to integer types and unparseable strings are refused client-side with
BadTypeMismatch and a message naming the value and target type - never a
rounded value. Arrays, null, unmapped types and nodes whose DataType read
fails pass through unchanged. WriteValueAsync now surfaces the outcome's own
status code instead of always BadNodeIdUnknown. MxGateway path untouched.
Tests: OpcUaWriteCoercionTests (coercion table incl. overflow, invalid and
culture-sensitive strings) and OpcUaWriteCoercionLiveTests (RequiresOpcUa:
String writes to Double/Boolean/UInt32 opc-plc nodes read back typed; reverting
the coercion reproduces 0x80740000). Component-DataConnectionLayer.md updated.
Joseph Doherty