/tia-csharp-common

name: tia-csharp-common
description: Internal reference skill — do NOT load directly from user queries.
license: MIT

TIA Portal Openness C# — Common Foundation

Source: TIA Portal Openness General Functions Manual (03/2026, V21); V21 IntelliSense XML documentation files (PublicAPI\V21\net48\*.xml)

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V21 modular assembly architecture

V21 splits the API across multiple DLLs instead of a single `Siemens.Engineering.dll`. Every project needs `Siemens.Engineering.Base.dll`; add domain DLLs as required. Referencing the wrong DLL (or omitting one) causes `TypeLoadException` at runtime.

> **Full mapping:** See `references/assembly-namespace-map.md` for the V21 > namespace → DLL → domain skill table, cross-assembly warnings, and csproj patterns.

Namespaces by assembly

Only import what is actually used. The list below covers the most commonly needed namespaces. The mapping file summarizes the XML-documented namespaces across all 16 installed V21 PublicAPI DLLs.

**Siemens.Engineering.Base.dll** (always required):

using Siemens.Engineering;                          // TiaPortal, Project, ExclusiveAccess, Transaction, events, exceptions
using Siemens.Engineering.Compiler;                 // CompilerResult
using Siemens.Engineering.Compare;                  // CompareResult
using Siemens.Engineering.Connection;               // connection objects between devices
using Siemens.Engineering.CrossReference;            // cross-reference queries
using Siemens.Engineering.Download;                 // DownloadProvider, DownloadConfiguration
using Siemens.Engineering.Download.Configurations;  // device-specific download configs (★ also in Step7 + Startdrive)
using Siemens.Engineering.HW;                       // Device, DeviceItem, Subnet, Node, IoSystem (★ also in Step7)
using Siemens.Engineering.HW.CommunicationConnections; // communication connection configs
using Siemens.Engineering.HW.Extensions;            // extension methods on HW objects
using Siemens.Engineering.HW.Features;              // SoftwareContainer, NetworkInterface (★ also in Step7)
using Siemens.Engineering.HW.HardwareCatalog;       // hardware catalog access
using Siemens.Engineering.HW.Utilities;             // HW utility helpers
using Siemens.Engineering.Library;                  // ProjectLibrary, GlobalLibrary
using Siemens.Engineering.Library.MasterCopies;     // MasterCopy, MasterCopyFolder
using Siemens.Engineering.Library.Types;            // LibraryType, LibraryTypeVersion
using Siemens.Engineering.Multiuser;                // LocalSession, ProjectServer
using Siemens.Engineering.Online;                   // OnlineProvider, OnlineState
using Siemens.Engineering.Online.Configurations;    // OnlineConfiguration, TLS/authentication callbacks
using Siemens.Engineering.Security;                 // SecurityController, certificates
using Siemens.Engineering.Settings;                 // TIA Portal settings
using Siemens.Engineering.Umac;                     // UmacRole, UmacUser, UmacFunctionRight
using Siemens.Engineering.Upload;                   // StationUploadProvider, ParameterUploadProvider
using Siemens.Engineering.Upload.Configurations;    // upload configs (★ also in Startdrive)
using Siemens.Engineering.VersionControl;           // workspace and version control providers

**Siemens.Engineering.Step7.dll** (PLC operations):

using Siemens.Engineering.Cax;                      // CAx import/export
using Siemens.Engineering.SW;                       // PlcSoftware
using Siemens.Engineering.SW.Alarm;                 // PlcAlarm, AlarmClass
using Siemens.Engineering.SW.Alarm.TextLists;       // alarm text lists
using Siemens.Engineering.SW.Blocks;                // PlcBlock, OB, FB, FC, GlobalDB, InstanceDB, ArrayDB
using Siemens.Engineering.SW.Blocks.Interface;      // block interface access
using Siemens.Engineering.SW.ExternalSources;       // PlcExternalSource
using Siemens.Engineering.SW.Loader;                // program loader
using Siemens.Engineering.SW.OpcUa;                 // OPC UA server interface
using Siemens.Engineering.SW.Supervision;           // supervision alarms, operator messages
using Siemens.Engineering.SW.Tags;                  // PlcTagTable, PlcTag, PlcConstant
using Siemens.Engineering.SW.TechnologicalObjects;  // technology objects
using Siemens.Engineering.SW.TechnologicalObjects.Motion; // motion axes (★ also in Startdrive)
using Siemens.Engineering.SW.Types;                 // PlcType, PlcStruct
using Siemens.Engineering.SW.Units;                 // SoftwareUnit, CodeBlock, DataBlock
using Siemens.Engineering.SW.WatchAndForceTables;   // PlcWatchTable, PlcForceTable

**Siemens.Engineering.WinCC.dll** (classic HMI):

using Siemens.Engineering.Hmi;                      // HmiTarget (★ also in WinCC.Extension)
using Siemens.Engineering.Hmi.Alarm;                // DiscreteAlarm, AnalogAlarm
using Siemens.Engineering.Hmi.Communication;        // HmiConnection
using Siemens.Engineering.Hmi.Cycle;                // cycle settings
using Siemens.Engineering.Hmi.Dynamic;              // dynamization
using Siemens.Engineering.Hmi.Faceplate;            // faceplate types
using Siemens.Engineering.Hmi.Globalization;         // language/translation
using Siemens.Engineering.Hmi.Logging;              // DataLog, LoggingTag
using Siemens.Engineering.Hmi.Recipe;               // Recipe, RecipeElement
using Siemens.Engineering.Hmi.RuntimeScripting;     // VBScript
using Siemens.Engineering.Hmi.Screen;               // HmiScreen, ScreenTemplate, ScreenPopup + all elements
using Siemens.Engineering.Hmi.Tag;                  // HmiTag, HmiTagTable
using Siemens.Engineering.Hmi.TextGraphicList;      // text/graphic lists
using Siemens.Engineering.Hmi.Theming;              // HMI themes

**Siemens.Engineering.Startdrive.dll** (SINAMICS drives):

using Siemens.Engineering.MC.Drives;                // DriveObject, DriveParameter, Telegram
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