All ribbon buttons in P8 are connected to an action. This means when calling a ribbon button, the respective action is executed. In order to execute an action via EPLAN API, you have to create an Action object and execute the action with the Execute method. 

In order to create an action object, you need to know the action by its name. You have to create a new ActionManager object call the findAction function, which takes the name of the action as parameter. 

For passing and evaluating action parameters, you need the ActionCallingContext class: 

String strAction = "TestAction";
ActionManager oAMnr= new ActionManager();
Action oAction= oAMnr.FindAction(strAction);
if (oAction != null)
{
    ActionCallingContext ctx = new ActionCallingContext();
    bool bRet=oAction.Execute(ctx);
    if (bRet)
    {               
    new Decider().Decide(EnumDecisionType.eOkDecision, "The Action " + strAction + " ended successfully!", "", EnumDecisionReturn.eOK, EnumDecisionReturn.eOK);
    }
    else
    {
    new Decider().Decide(EnumDecisionType.eOkDecision, "The Action " + strAction + " ended with errors!", "", EnumDecisionReturn.eOK, EnumDecisionReturn.eOK);
    }
}

Dim strAction As String = "TestAction"
Dim oAMnr As New ActionManager()
Dim oAction As Action = oAMnr.FindAction(strAction)
Dim dec As Decider = New Decider
If Not (oAction Is Nothing) Then
   Dim ctx As New ActionCallingContext()
   Dim bRet As Boolean = oAction.Execute(ctx)
   If bRet Then
      dec.Decide(EnumDecisionType.eOkDecision, "The Action " + strAction + " ended successfully!", "", EnumDecisionReturn.eOK, EnumDecisionReturn.eOK)              
   Else
      dec.Decide(EnumDecisionType.eOkDecision, "The Action " + strAction + " ended with errors!", "", EnumDecisionReturn.eOK, EnumDecisionReturn.eOK)
   End If
End If

To find out, which action is connected to which ribbon button, you can evaluate the "onActionStart.String.*" event. Alternatively, after clicking the ribbon button, press [Ctrl]+[VK_OEM_5] to show the "Diagnose Dialog". [VK_OEM_5] corresponds to the [^] key on a German keyboard or to the [\] on a United States 101 keyboard. 

For a list of automatic actions refer to the topic Automatic Actions 

Important: 

Please mind, that an Action may modify the ActionCallingContext dureing its execution. Sometimes e.g. project Ids are added to the context and are passed to an inner action. Re-using the same ActionCallingContext for a further Action call may lead to unexpected results. So in most cases, it is advisable to create a new ActionCallingContext for a new Action call. 

Command line call

In order to enhance the EPLAN command line with new commands and parameters, you need to implement an action. The action can have its own parameters and can call other API functions. 

This way an action is executed just after starting EPLAN, for example: 

EPLAN.EXE /Variant:"Electric P8" /NoLoadWorkspace action /Param1:value1 /Param2:value2 /Param3:value3 

The parameter without flag (/ or -) is interpreted as name of an action to be executed. All following parameters are passed to the action. Only one action per command line call is possible. 

A script can also contain and register an action. This means it can also evaluate action parameters. 

It is necessary to pass further general command line parameters before the action name. 

List of general command line parameters evaluated by EPLAN:

Every command line parameter behind the name of the action thus is passed as parameters to the action. The parameters are wrapped into an ActionCallingContext as string parameters and can be extracted by the Action. Please pay attention to spell the parameter names in command line and ActionCallingContext in exactly the same way: 

EPLAN.EXE /Variant:"Electric P8" action /Param1:value1 /Param2:value2 /Param3:value3 

public bool Execute(ActionCallingContext ctx )
{
   String strParamValue1=null;
   ctx.GetParameter("Param1", ref strParamValue1);
   String strParamValue2=null;
   ctx.GetParameter("Param2", ref strParamValue2);
   String strParamValue3=null;
   ctx.GetParameter("Param3", ref strParamValue3);
   return true;
}

Public Function Execute(ctx As ActionCallingContext) As Boolean Implements IEplAction
   Dim strParamValue1 As String = Nothing
   ctx.GetParameter("Param1", strParamValue1)
   Dim strParamValue2 As String = Nothing
   ctx.GetParameter("Param2", strParamValue2)
   Dim strParamValue3 As String = Nothing
   ctx.GetParameter("Param3", strParamValue3)
   Return True
End Function 'Execute

 Warning: when starting EPLAN from command line with an action, then no previously opened projects are opened at the beginning of the session.