OpcDaItemProperty.Value always return null

[AlexeyTipunin]

Hello. Why when i call var props = browser.GetProperties(new List() {element.ItemId}); Value for all prepertys is null?

[trkeast]

Hello Alexey!

a few questions:

1. what version of opcda has been used?
2. which opc server was used?

I tried to reproduce your situation to 'Matrikon.Simulation.Server.1' for opcda with version 1,2 and 3, GetProperties returned not empty Array of OpcDaItemProperties objects. Some opc servers may be different of matrikon behavior opc in realization

[AlexeyTipunin]

I use Kepware.KEPServerEX.V6 and enabled OPC 1,2,3

[trkeast]

i will try to reproduce this situation on keptware opc

[trkeast]

try set Culture property to InvariantCulture or en-US (1033) culture on created OpcDaServer object, similary this code:

OpcDaServer server = new OpcDaServer(UrlBuilder.Build("Kepware.KEPServerEX.V6"));
server.Culture = CultureInfo.InvariantCulture; //or CultureInfo.GetCultureInfo(1033);
server.connect();

OpcDaBrowser3 browser = new OpcDaBrowser(server);

OpcDaItemProperties[] properties = browser.GetProperties(new []{"ItemId"});

[AlexeyTipunin]

I can not find OpcDaBrowser data type. I try this:

OpcDaServer server = new OpcDaServer(UrlBuilder.Build("Kepware.KEPServerEX.V6"));

server.connect();
server.Culture = CultureInfo.GetCultureInfo(1033);

var browser = new OpcDaBrowserAuto(server);
OpcDaItemProperties[] properties = browser.GetProperties(new []{"Channel1.Device1.Tag1"});

but it is not work

[AlexeyTipunin]

How to make work unit tests? я get an error: CoCreateInstanceEx: Class not registered

[AlexeyTipunin]

MS tests works well, but nunit not.

[alexey-kachalov]

Hi there.

Check Opc Core Components (https://opcfoundation.org/developer-tools/developer-kits-classic/core-components) installed on your system first. It is possible you have not installed OPCEnum service.

Also to locate an exception point, try to use classes OpcDaBrowser1 (for OPC DA 1.0 browser), OpcDaBrowser2 (for OPC DA 2.05 browser) or OpcDaBrowser3 (for OPC DA 3.0 browser) instead of OpcDaBrowserAuto.

To run unit tests in NUnit, it should be configured with x86 envirenment.

Good luck!

[AlexeyTipunin]

Thank you, alexey-kachalov! Tests have earned.

[pranny]

I am also viewing empty values. In my case, I am using Matrikon OPC Simulator Server. The relevent part of code are as follows

                var browser = new OpcDaBrowserAuto(server);
                OpcDaItemProperties[] properties = browser.GetProperties(tags.ToArray());
                foreach(OpcDaItemProperties prop in properties)
                {
                    string msg2 = "";
                    foreach(OpcDaItemProperty _prop in prop.Properties)
                    {
                        msg2 += _prop.ToString() + "\n";
                    }
                    eventLog.WriteEntry(msg2);
                }

The log that I get is as follows

1 Item Canonical DataType (ItemId: Random.Int4, DataType System.Int16, Value: , ErrorId: S_OK: Success code)
2 Item Value (ItemId: Random.Int4, DataType TitaniumAS.Opc.Client.Common.IllegalType, Value: , ErrorId: S_OK: Success code)
3 Item Quality (ItemId: Random.Int4, DataType System.Int16, Value: , ErrorId: S_OK: Success code)
4 Item Timestamp (ItemId: Random.Int4, DataType System.DateTime, Value: , ErrorId: S_OK: Success code)
5 Item Access Rights (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)
6 Server Scan Rate (ItemId: Random.Int4, DataType System.Single, Value: , ErrorId: S_OK: Success code)
7 Item EU Type (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)
8 Item EUInfo (ItemId: Random.Int4, DataType System.String[], Value: , ErrorId: S_OK: Success code)
101 Item Description (ItemId: Random.Int4, DataType System.String, Value: , ErrorId: S_OK: Success code)
-5 Triangle Wave (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)
-4 Square Wave (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)
-3 Saw-toothed Wave (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)
-2 Random (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)
-1 Bucket Brigade (ItemId: Random.Int4, DataType System.Int32, Value: , ErrorId: S_OK: Success code)

I tried with OpcDaBrowser1, OpcDaBrowser2 and OpcDaBrowser3 as well. I got the error like below for 2 and 1

1 Item Canonical DataType (ItemId: , DataType TitaniumAS.Opc.Client.Common.IllegalType, Value: , ErrorId: OPC_E_INVALID_PID: The specified property ID is not valid for the item.)

I am using CultureInfo.GetCultureInfo(1033) and also tried with InvariantCulture or en-US (1033) culture without any success.

Any ideas?

[pranny]

I found a workaround for this. The workaround gets the value of OPC Datatype. Here is the code. P.S. I only needed the canonical data type for the tags.

OpcDaItemProperties[] properties = browser.GetProperties(tags.ToArray(), new OpcDaPropertiesQuery(true, new int[] { 1 }));

...

 foreach (OpcDaItemProperty _prop in prop.Properties)
                {
                    if (_prop.PropertyId == 1)
                    {
                        if (_prop.Value == null)
                        {
                            tag_data_types[_prop.ItemId] = "na";
                        }
                        else
                        {
                            tag_data_types[_prop.ItemId] = _prop.Value.ToString();
                        }
                    }
                }

Update:

This workaround does not work always. In an instance, I found that I was still getting INVALID_PID error. In order to verify, I installed and tried with OpenOPC. The OpenOPC gave me correct values for Canonical Data Type.

@alexey-kachalov Any help greatly appreciated. Is there a way to read the properties of elements without creating or group?

[gtan14]

@pranny were you able to find a permanent solution to this? I'm getting all empty values as well for my items