How write bytes in PLC #1372

sergeishugaev · 2025-02-03T13:53:14Z

sergeishugaev
Feb 3, 2025

Hello!
I try to write some variables to PLC use Milo 0.6.14, but not all variables are written.
In example below I write 4 variable: boolean control, byte index, byte output, int weight.
In PLC, these variables have the type: BOOL, BYTE, BYTE, DINT
boolean and int variable are being written successfully, but byte variables aren't.
I try changed type of variable in java to short, int, but it didn't help.
In PCL BYTE (0...255), in java byte (-128...127).
What am I doing wrong?
How do I write byte variables?

I'll notice, the reading byte variables was successful.

Please help me.
Thanks!

...
NodeId nodeId_astSiloParameters_xControl = NodeId.parse("ns=4;s=|var|SPK107 (M01).Application.GVL.astSiloParameters[1].xControl");
NodeId nodeId_astSiloParameters_byIndex = NodeId.parse("ns=4;s=|var|SPK107 (M01).Application.GVL.astSiloParameters[1].byIndex");
NodeId nodeId_astSiloParameters_byOutput = NodeId.parse("ns=4;s=|var|SPK107 (M01).Application.GVL.astSiloParameters[1].byOutput");
NodeId nodeId_astSiloParameters_diSetWeight = NodeId.parse("ns=4;s=|var|SPK107 (M01).Application.GVL.astSiloParameters[1].diSetWeight");

List<NodeId> nodeIds = new ArrayList<>();
List<DataValue> dataWriteValues = new ArrayList<>();
nodeIds.add(nodeId_astSiloParameters_xControl);
dataWriteValues.add(new DataValue(new Variant(control), null, null));
nodeIds.add(nodeId_astSiloParameters_byIndex);
dataWriteValues.add(new DataValue(new Variant(index), null, null));
nodeIds.add(nodeId_astSiloParameters_byOutput);
dataWriteValues.add(new DataValue(new Variant(output), null, null));
nodeIds.add(nodeId_astSiloParameters_diSetWeight);
dataWriteValues.add(new DataValue(new Variant(weight), null, null));

opcUaClient.writeValues(nodeIds, dataWriteValues);

kevinherron · 2025-02-05T17:48:32Z

kevinherron
Feb 5, 2025
Maintainer

"Byte" in OPC UA is an unsigned byte.

Try using the UByte type provided by Milo.

1 reply

sergeishugaev Feb 6, 2025
Author

Thank you very much!
I didn't know that Milo had corresponding data types.

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kevinherron Feb 5, 2025 Maintainer

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sergeishugaev Feb 6, 2025 Author

sergeishugaev
Feb 3, 2025

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kevinherron
Feb 5, 2025
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sergeishugaev Feb 6, 2025
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