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eplanbridge

Tovex Dev project - README

csharp · 2026 · Active

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csharp · eplan · eplan-pro-panel · industrial-automation · mcp

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Readme

Drive EPLAN Pro Panel 2022.0.3 from outside the application — and build a 6-axis robot-arm control schematic with it.

A programmable control surface for EPLAN Pro Panel, shaped like the existing gxbridge MCP server, plus the project it was built to produce: RoboArm_6DOF_FX5U, a 20-page schematic for an FX5U-controlled 6-axis arm — 273 symbols and 129 connections, all placed by script.

Read these first

Each records what was measured and what is still a guess. Read the relevant one before changing anything.

Why

EPLAN has no supported way to build a schematic in bulk from outside the GUI. Drawing 273 symbols and wiring them by hand is slow and unrepeatable; doing it from a script makes the drawing a build artefact that can be rebuilt, diffed, and corrected. This project works out what that takes and records the parts that are not obvious — chiefly that placement alone connects nothing.

Why it is built this way

EPLAN's remoting channel exposes exactly one useful verb: ExecuteAction. The interesting API — DataModel, DataModel.E3D, HEServices — is in-process only. The bridge between them is EPLAN's ExecuteScript action.

But EPLAN's script compiler carries no reference to Eplan.EplApi.DataModelu.dll. Any compile-time mention of that namespace fails the whole script, and a failed compile is reported as Succeed=False with an empty message — no error text anywhere. That single fact dictates the design.

  PowerShell / MCP server           (out of process, net48)
        |  EplanRemoteClient.ExecuteAction
        v
  ExecuteScript /ScriptFile:EplanBridgeStub.cs
        |  (the ONLY reflection in the system)
        v
  EplanBridge.Core.dll              (in process, typed C#, full API access)

EplanBridgeStub.cs names no EPLAN API type, so it always compiles. It loads EplanBridge.Core.dll and calls Bridge.Invoke(command, argument). Everything below that boundary is ordinary typed C# — which means the compiler checks the API usage instead of mistakes surfacing at runtime.

The stub loads the DLL from a byte array, not Assembly.LoadFrom. That leaves the file unlocked, so EplanBridge.Core can be rebuilt without restarting EPLAN. Verified working.

Layout

Build

cd src\EplanBridge.Core
dotnet build -c Release -o ..\..\bin

Targets net48 because the EPLAN API is .NET Framework. The only SDK installed is .NET 10, which cannot load Framework assemblies in-process — but it builds net48 fine, since the targeting pack is present. EPLAN references use false so its DLLs are never copied; the process already has them loaded.

Use

.\tools\Invoke-EplanBridge.ps1 -Command ping
.\tools\Invoke-EplanBridge.ps1 -Command project.info `
    -Argument 'C:\Users\Kishor\Tovex-Work\eplan-propanel-bridge\projects\RoboArm_6DOF_FX5U.elk'

-Port defaults to 57315 (the dedicated instance). Start a dedicated instance with an explicit port rather than an ephemeral one:

Eplan.exe /Variant:"Pro Panel" EplanServer /EPLANSERVERPORT:<port>

Verify

With a dedicated EPLAN instance running on port 57315:

.\tools\Get-ProjectAudit.ps1

Success is the last three lines reading exactly:

total functions   = 273
total connections = 129
untagged (=+)     = 273

and every page =RA1+CAB/2 through /17 reporting a non-zero function count. The audit reopens the project from disk, so a passing run is also the persistence proof — there is no Save in this API, only Project.Close().

untagged = 273 is the expected value, not a failure to investigate: device numbering does not work yet (FINDINGS §3). It will drop to 0 when it does.

Parts allocation

.\tools\Invoke-EplanBridge.ps1 -Command project.parts `
    -Argument 'C:\Users\Kishor\Tovex-Work\eplan-propanel-bridge\projects\RoboArm_6DOF_FX5U.elk'

Success is withoutPart reading 0:

{"totalFunctions":169,"withPart":144,"withoutPart":0,
 "cannotCarryArticle":25,"distinctParts":9}

totalFunctions is 169 here and 273 in the audit above, and both are correct. The audit sums 16 page-filtered queries; this is one project-wide query, and GetFunctions(null) does not return the 104 PLC connection points. Do not "fix" either number to match the other.

Rebuild from scratch and re-verify

.\tools\Build-RoboArmSchematic.ps1
.\tools\Invoke-EplanAction.ps1 -Actions 'generate /TYPE:CONNECTIONS /PROJECTNAME:"C:\Users\Kishor\Tovex-Work\eplan-propanel-bridge\projects\RoboArm_6DOF_FX5U.elk" /REBUILDALLCONNECTIONS:1'
.\tools\Invoke-EplanBridge.ps1 -Command project.close -Argument 'C:\Users\Kishor\Tovex-Work\eplan-propanel-bridge\projects\RoboArm_6DOF_FX5U.elk'
.\tools\Get-ProjectAudit.ps1

Commands

Page types accepted by page.create: Circuit, TitlePage, TableOfContents, PLCDiagram, PLCCardOverview, TerminalDiagram, PanelLayout, Overview, and the rest of DocumentTypeManager.DocumentType.

Rules for adding a command

• One command, one verb, one effect. Never "create or update".
• Return JSON always. Never throw across the boundary; never show a dialog — a modal

dialog blocks every later remote call, since EPLAN only services remote calls when idle.

• Data-model writes must be wrapped in a LockingStep, or EPLAN throws

NoLockingStepException (S063110).

• A project already open cannot be re-opened. Use GetProject first (returns null

when not open), then OpenProject.

• State in the command's docs what it cannot do.

API gotchas found the hard way

There is no Save. The only persistence trigger is Project.Close(). Verified: after creating 19 pages, Page.eod was still 1,134 bytes at its original timestamp; after project.close it became 22,680 bytes, and reopening from disk (wasAlreadyOpen:false) returned all 20 pages. Never report a write as done before closing — an in-memory read-back proves nothing.

Placing symbols does not connect them. EPLAN auto-connects connection points that share an X coordinate and face each other, but only when generate /TYPE:CONNECTIONS /REBUILDALLCONNECTIONS:1 is run. Place → generate → close. Skip the middle step and you get a drawing that looks right and is electrically empty.

Place symbols with SymbolVariant.Create(page), never Function.Create. Function.Create only builds generic Functions. For a symbol backed by a specialised class (terminals, cables, PLC boxes) it creates the object and then throws NotImplementedException — leaving a half-initialised object on the page while reporting failure. Observed exactly: four terminals reported FAIL yet all appeared in page.contents. SymbolVariant.Create returns the correct subclass; set SymbolReference.Location afterwards.

Device tags cannot be set as a property. FUNC_DEVICETAG_FULL throws NotImplementedException; NameParts has no FUNC_DEVICETAG_MAINNAME; there are no IDENTLETTER/COUNTER name-part properties on FunctionBasePropertyList. EPLAN assigns device tags with its own renumber action — place first, number after.

The page description property is PAGE_NOMINATIOMN — EPLAN's own misspelling, documented as "Page description # 11011". There is no PAGE_DESCRIPTION. PAGE_SUPPLEMENTARYFIELD is a different, indexed property (11901) and is the wrong choice.

Read the full README on GitHub →

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