mapper.Map(railData, new UAMappingContext
 {
   EndpointDescriptor = endpointDescriptor,
   NodeDescriptor = new UANodeDescriptor
   {
     BrowsePath = UABrowsePath.Parse("[ObjectsFolder]/Application/PersistentVars/Application&.PersistentVars&.astFrontRailPositions.Application&.PersistentVars&.astFrontRailPositions[1]", "urn:Schneider:M262:customprovider")
   }
 });;

class PersistentVars
{
  [UANode(BrowsePath = ".Application&.PersistentVars&.astFrontRailPositions[1]&")]
  public Rail _rail = new();
}
 
[UAType]
class Rail
{
 
  [UAData(Operations = UADataMappingOperations.Read)]
  public Boolean InUse { get; set; }
 
  [UAData(Operations = UADataMappingOperations.Read)]
  public Int16 InUseType { get; set; }
 
  [UAData(Operations = UADataMappingOperations.Read, Kind = UADataMappingKind.Exception)]
  public Exception? Master { get; set; }
 
  [UAData(Operations = UADataMappingOperations.Read)]
  public Int32 Slave { get; set; }
}
 

OpcLabs.EasyOpc.UA.UAServiceException: OPC UA service result - {BadNoMatch}. The requested operation has no match to return.
+ The client method called (or event/callback invoked) was 'ReadMultiple[4]'.
......

 UAEndpointDescriptor endpointDescriptor =
             "opc.tcp://10.151.251.100:4840/UADiscovery";
 
 var mapper = new UAClientMapper();
 var LiveMappingTest = new PersistentVarsTest();
 mapper.Map(LiveMappingTest, new UAMappingContext
 {
     EndpointDescriptor = endpointDescriptor,   
 
     NodeDescriptor = new UANodeDescriptor
         {
             BrowsePath = UABrowsePath.Parse("[nsu=urn:Schneider:M262:customprovider;i=85]/Application/PersistentVars/Application", "urn:Schneider:M262:customprovider")
     },
     MonitoringParameters = 1000,
 });

[UANamespace("urn:Schneider:M262:customprovider")]
 
 [UAType]
 
class PersistentVarsTest
 
 {
 
// Specifying BrowsePath-s here only because we have named the class members differently from OPC node names.
 
 [UANode(BrowsePath = ".PersistentVars")]
 
public CustomController CustomController = new CustomController();
 
 }
 
 
 
class CustomController
 
 {
 
 [UANode(BrowsePath = ".diHMIDrawerHomeAcc"), UAData(Operations = UADataMappingOperations.Read)]    // not readable
 
public int diHMIDrawerHomeAcc { get; set; }
 
}