TrakHound · ottobolyos · Apr 30, 2026
diff --git a/MTConnect.NET.sln b/MTConnect.NET.sln
@@ -119,6 +119,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Agent", "templates\mtconnec
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MTConnect.NET.Builder", "build\MTConnect.NET.Builder\MTConnect.NET.Builder.csproj", "{FC9965F9-63B4-3BE9-FD8E-28B7C8E19A19}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MTConnect.NET-JSON-cppagent-Tests", "tests\MTConnect.NET-JSON-cppagent-Tests\MTConnect.NET-JSON-cppagent-Tests.csproj", "{07AB00DA-2D48-4089-8F19-203F39B4DC99}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -423,6 +425,14 @@ Global
 		{FC9965F9-63B4-3BE9-FD8E-28B7C8E19A19}.Package|Any CPU.Build.0 = Debug|Any CPU
 		{FC9965F9-63B4-3BE9-FD8E-28B7C8E19A19}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{FC9965F9-63B4-3BE9-FD8E-28B7C8E19A19}.Release|Any CPU.Build.0 = Release|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Docker|Any CPU.ActiveCfg = Debug|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Docker|Any CPU.Build.0 = Debug|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Package|Any CPU.ActiveCfg = Debug|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Package|Any CPU.Build.0 = Debug|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -468,6 +478,7 @@ Global
 		{24C98CF3-CC93-4696-A036-8FD1E16F2E7E} = {FFF032D3-7446-4CAF-A3E3-CF9C4E1A5DCC}
 		{FF3FACB1-C470-4C7F-9A4B-F364BE1E32B3} = {D7873DF2-16DB-4B19-A100-C0089DF37488}
 		{FC9965F9-63B4-3BE9-FD8E-28B7C8E19A19} = {BBF53739-168D-4635-8595-083AC0C65E4C}
+		{07AB00DA-2D48-4089-8F19-203F39B4DC99} = {14375E03-6BF8-45E6-B868-D2399368992B}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {CC13D3AD-18BF-4695-AB2A-087EF0885B20}

diff --git a/libraries/MTConnect.NET-JSON-cppagent/Streams/JsonConditions.cs b/libraries/MTConnect.NET-JSON-cppagent/Streams/JsonConditions.cs
@@ -9,6 +9,7 @@
 
 namespace MTConnect.Streams.Json
 {
+    [System.Text.Json.Serialization.JsonConverter(typeof(JsonConditionsConverter))]
     public class JsonConditions
     {
         [JsonIgnore]
@@ -113,5 +114,5 @@ public JsonConditions(IEnumerable<IObservationOutput> observations)
                 }
             }
         }
-    }  
+    }
 }
diff --git a/libraries/MTConnect.NET-JSON-cppagent/Streams/JsonConditionsConverter.cs b/libraries/MTConnect.NET-JSON-cppagent/Streams/JsonConditionsConverter.cs
@@ -0,0 +1,177 @@
+// Copyright (c) 2023 TrakHound Inc., All Rights Reserved.
+// TrakHound Inc. licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace MTConnect.Streams.Json
+{
+    // Serializes JsonConditions in the cppagent JSON v2 wire shape: an
+    // ordered array of single-key wrapper objects, one per Condition entry
+    // (e.g. [{"Normal": {...}}, {"Warning": {...}}]). The XSD
+    // ConditionListType is <xs:sequence><xs:choice maxOccurs='unbounded'>
+    // of Normal|Warning|Fault|Unavailable, so the wire shape preserves
+    // observation order. The legacy MTConnect JSON v1 object-keyed shape
+    // ({"Fault": [...], "Warning": [...], ...}) is still accepted on the
+    // read path for back-compat.
+    internal sealed class JsonConditionsConverter : JsonConverter<JsonConditions>
+    {
+        private const string FaultLevel = "Fault";
+        private const string WarningLevel = "Warning";
+        private const string NormalLevel = "Normal";
+        private const string UnavailableLevel = "Unavailable";
+
+        public override JsonConditions Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
+        {
+            switch (reader.TokenType)
+            {
+                case JsonTokenType.Null:
+                    return null;
+
+                case JsonTokenType.StartArray:
+                    return ReadArrayShape(ref reader, options);
+
+                case JsonTokenType.StartObject:
+                    return ReadObjectShape(ref reader, options);
+
+                default:
+                    throw new JsonException(
+                        $"Unexpected token '{reader.TokenType}' when reading JsonConditions; expected array, object, or null.");
+            }
+        }
+
+        public override void Write(Utf8JsonWriter writer, JsonConditions value, JsonSerializerOptions options)
+        {
+            if (value == null)
+            {
+                writer.WriteNullValue();
+                return;
+            }
+
+            writer.WriteStartArray();
+
+            WriteLevel(writer, FaultLevel, value.Fault, options);
+            WriteLevel(writer, WarningLevel, value.Warning, options);
+            WriteLevel(writer, NormalLevel, value.Normal, options);
+            WriteLevel(writer, UnavailableLevel, value.Unavailable, options);
+
+            writer.WriteEndArray();
+        }
+
+        private static void WriteLevel(Utf8JsonWriter writer, string levelName, IEnumerable<JsonCondition> entries, JsonSerializerOptions options)
+        {
+            if (entries == null) return;
+
+            foreach (var entry in entries)
+            {
+                writer.WriteStartObject();
+                writer.WritePropertyName(levelName);
+                JsonSerializer.Serialize(writer, entry, options);
+                writer.WriteEndObject();
+            }
+        }
+
+        private static JsonConditions ReadArrayShape(ref Utf8JsonReader reader, JsonSerializerOptions options)
+        {
+            var faults = new List<JsonCondition>();
+            var warnings = new List<JsonCondition>();
+            var normals = new List<JsonCondition>();
+            var unavailables = new List<JsonCondition>();
+
+            while (reader.Read())
+            {
+                if (reader.TokenType == JsonTokenType.EndArray) break;
+
+                if (reader.TokenType != JsonTokenType.StartObject)
+                {
+                    throw new JsonException(
+                        $"Unexpected token '{reader.TokenType}' inside JsonConditions array; expected object wrapper.");
+                }
+
+                if (!reader.Read() || reader.TokenType != JsonTokenType.PropertyName)
+                {
+                    throw new JsonException("Expected property name inside JsonConditions wrapper object.");
+                }
+
+                var levelName = reader.GetString();
+                reader.Read();
+                var entry = JsonSerializer.Deserialize<JsonCondition>(ref reader, options);
+
+                if (!reader.Read() || reader.TokenType != JsonTokenType.EndObject)
+                {
+                    throw new JsonException("Expected end of JsonConditions wrapper object after entry.");
+                }
+
+                switch (levelName)
+                {
+                    case FaultLevel:
+                        faults.Add(entry);
+                        break;
+                    case WarningLevel:
+                        warnings.Add(entry);
+                        break;
+                    case NormalLevel:
+                        normals.Add(entry);
+                        break;
+                    case UnavailableLevel:
+                        unavailables.Add(entry);
+                        break;
+                    default:
+                        throw new JsonException(
+                            $"Unknown Condition level '{levelName}' in JsonConditions array; expected Fault, Warning, Normal, or Unavailable.");
+                }
+            }
+
+            return new JsonConditions
+            {
+                Fault = faults.Count > 0 ? faults : null,
+                Warning = warnings.Count > 0 ? warnings : null,
+                Normal = normals.Count > 0 ? normals : null,
+                Unavailable = unavailables.Count > 0 ? unavailables : null,
+            };
+        }
+
+        private static JsonConditions ReadObjectShape(ref Utf8JsonReader reader, JsonSerializerOptions options)
+        {
+            var result = new JsonConditions();
+
+            while (reader.Read())
+            {
+                if (reader.TokenType == JsonTokenType.EndObject) break;
+
+                if (reader.TokenType != JsonTokenType.PropertyName)
+                {
+                    throw new JsonException(
+                        $"Unexpected token '{reader.TokenType}' inside JsonConditions object; expected property name.");
+                }
+
+                var levelName = reader.GetString();
+                reader.Read();
+                var entries = JsonSerializer.Deserialize<List<JsonCondition>>(ref reader, options);
+
+                switch (levelName)
+                {
+                    case FaultLevel:
+                        result.Fault = entries;
+                        break;
+                    case WarningLevel:
+                        result.Warning = entries;
+                        break;
+                    case NormalLevel:
+                        result.Normal = entries;
+                        break;
+                    case UnavailableLevel:
+                        result.Unavailable = entries;
+                        break;
+                    default:
+                        throw new JsonException(
+                            $"Unknown Condition level '{levelName}' in JsonConditions object; expected Fault, Warning, Normal, or Unavailable.");
+                }
+            }
+
+            return result;
+        }
+    }
+}
diff --git a/tests/MTConnect.NET-JSON-cppagent-Tests/MTConnect.NET-JSON-cppagent-Tests.csproj b/tests/MTConnect.NET-JSON-cppagent-Tests/MTConnect.NET-JSON-cppagent-Tests.csproj
@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <RootNamespace>MTConnect.NET_JSON_cppagent_Tests</RootNamespace>
+    <Nullable>disable</Nullable>
+
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.11.0" />
+    <PackageReference Include="NUnit" Version="3.13.2" />
+    <PackageReference Include="NUnit3TestAdapter" Version="4.0.0" />
+    <PackageReference Include="coverlet.collector" Version="3.1.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\libraries\MTConnect.NET-JSON-cppagent\MTConnect.NET-JSON-cppagent.csproj" />
+  </ItemGroup>
+
+</Project>