The extension object cannot be (de)serialized because the data type id is not recognized. StatusBadDataTypeIDUnknown

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I'm writing an example to read and deserialize a node value of Extension Object, but it didn't work at all for me. I reviewed similar threads and examples, and still have no idea how to make it working. Any advice or information are greatly appreciated.

From the UaExpert, the node and its data type is:

Then I created an testing program to read and process that ndoe:

package main

import (
	"context"
	"log"
	"time"

	"github.com/gopcua/opcua"
	"github.com/gopcua/opcua/ua"
)

const (
	endpoint   = "opc.tcp://192.168.70.22:4840"
	nodeID     = "ns=4;s=|var|WAGO 750-8212 PFC200 G2 2ETH RS.Application.ControllerTags.SCADA_R_Tx"
	nodeTypeID = "ns=4;s=|dtd|WAGO 750-8212 PFC200 G2 2ETH RS.Application.SCADA_R_TRAIN_UDT"
	timeout    = 30
)

func main() {
	ctx, cancel := func() (context.Context, context.CancelFunc) {
		if timeout > 0 {
			return context.WithTimeout(context.Background(), time.Duration(timeout)*time.Second)
		}
		return context.WithCancel(context.Background())
	}()
	defer cancel()

	opts := []opcua.Option{
		opcua.AuthAnonymous(),
		opcua.AutoReconnect(true),
		opcua.ReconnectInterval(time.Duration(10) * time.Minute),
		opcua.RequestTimeout(300 * time.Second),
	}
	log.Println("creating OPCUA client")
	c, err := opcua.NewClient(endpoint, opts...)
	if err != nil {
		log.Fatal(err)
	}

	log.Println("connecting")
	if err := c.Connect(ctx); err != nil {
		log.Fatal(err)
	}
	defer c.Close(ctx)

	log.Println("requesting value of node:", nodeID)
	v, err := c.Node(ua.MustParseNodeID(nodeID)).Value(ctx)
	if err != nil {
		log.Fatal(err)
	}
	log.Printf("Value: %#v", v)
}

type SCADA_R_TRAIN_UDT struct {
	T_Dint [21]int32
	T_REAL [56]float32
}

func init() {
	log.Println("init - registering object")
	ua.RegisterExtensionObject(ua.MustParseNodeID(nodeTypeID), new(SCADA_R_TRAIN_UDT))
	log.Printf("init - object registered: %#v", ua.ExtensionObjectTypeID(new(SCADA_R_TRAIN_UDT)).String())
}

From the logs, the program run well but still failed to read the node:

$ go build test.go
$ ./test 
2024/07/23 07:26:01 init - registering object
2024/07/23 07:26:01 init - object registered: "ns=4;s=|dtd|WAGO 750-8212 PFC200 G2 2ETH RS.Application.SCADA_R_TRAIN_UDT"
2024/07/23 07:26:01 creating OPCUA client
2024/07/23 07:26:01 connecting
2024/07/23 07:26:02 requesting value of node: ns=4;s=|var|WAGO 750-8212 PFC200 G2 2ETH RS.Application.ControllerTags.SCADA_R_Tx
2024/07/23 07:26:02 The extension object cannot be (de)serialized because the data type id is not recognized. StatusBadDataTypeIDUnknown (0x80110000)

Any suggestions or comments are greatly appreciated.