OPC DA to OPC UA pipeline: “uncertain” tags are becoming “BAD”

[_FIreDemon_]

I was trying to use Rapid-Scada Communicator to transfer tags from OPC DA server (Yokogawa Exaopc) to Linux client machine via OPC UA protocol. Everything works fine for tags with “GOOD” quality, however, tags with “uncertain” quality are transferred as “BAD” quality with now value in them. More strangely, I can write in these tags from Linux client with no errors but the quality will remain “BAD”.

[_FIreDemon_]

OPC DA
https://drive.google.com/file/d/1y8m5wg-oXUFpGq9bavAB-_p8a24wRZ0s/view?usp=sharing

Rapid-Scada
https://drive.google.com/file/d/1TCACIux7n7zkb4oDHjWiY51Z_hrItb5O/view?usp=sharing

OPC UA
https://drive.google.com/file/d/11GEcDLJRHR_lI0dfSCKKMhj1ejalNUvv/view?usp=sharing

• This reply was modified 4 months, 3 weeks ago by Mikhail.

[_FIreDemon_]

Sorry, don’t know why the images were not properly loaded, here is the link on imgur:
Images

[Mikhail]

Hello,
The OPC Classic driver requires GOOD quality to display data as valid. Otherwise, it marks the tag as undefined. Undefined tags are provided to OPC UA with BAD quality.

[_FIreDemon_]

Thank you for your answer, Mikhail. Is there any way to bypass this?

[Mikhail]

I suppose, it’s better to fix the OPC server to get GOOD values.
Alternatively, you can change the source code of the driver to solve this certain issue for your needs. There is no plan to change the driver for all users, because “uncertain” means that data is not good.

• This reply was modified 4 months, 3 weeks ago by Mikhail.

[_FIreDemon_]

As far as I know, this is an expected behavior for tags in manual mode.
Anyways, do you mind sharing a guide or a link for the already existing solution on how to compile a new driver with this bypass?

[Mikhail]

> As far as I know, this is an expected behavior for tags in manual mode.
May be you right.

1. Download and try to build the community part as described here.
2. Download and try to build the OPC Classic driver. Link
When the above is done, I’ll help to find the code to change.

[_FIreDemon_]

So, I’ve built everything. The only problem was that my NuGet couldn’t find
<PackageReference Include=”OpcComRcw” Version=”2.1.108″ />
<PackageReference Include=”OpcNetApi” Version=”2.1.108″ />
<PackageReference Include=”OpcNetApi.Com” Version=”2.1.108″ />
and I had to use “Quick.” version of these packages

[Mikhail]

You can find that DLLs in the Rapid SCADA installation folder.

[_FIreDemon_]

Ok, I’ve compiled everything using those DLLs

[_FIreDemon_]

I’ve changed condition in DevOpcClassicLogic.cs from

/// <summary>
/// Gets the tag status corresponding to the item quality.
/// </summary>
private static int GetTagStatus(Opc.Da.ItemValueResult itemValue)
{
 return itemValue.QualitySpecified && itemValue.Quality.QualityBits == Opc.Da.qualityBits.good ?
 CnlStatusID.Defined : CnlStatusID.Undefined;
}

to

private static int GetTagStatus(Opc.Da.ItemValueResult itemValue)
{
 return itemValue.QualitySpecified && itemValue.Quality.QualityBits == Opc.Da.qualityBits.good || itemValue.QualitySpecified && itemValue.Quality.QualityBits == Opc.Da.qualityBits.uncertain ?
 CnlStatusID.Defined : CnlStatusID.Undefined;
}

Then I’ve compiled DrvOpcClassic.Logic.csproj and swapped the driver logic DLL. Now “uncertain” tags are showing in OPC UA. Hope this is a somewhat safe change.
Thanks a lot for the help!

• This reply was modified 4 months, 2 weeks ago by _FIreDemon_.

[Mikhail]

🙂

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