Command Login

Symbol: Command Login 1:

Function: This command connects the programming system (the selected PLC project) with the target system (controller) and thus establishes online operation. An instance of the PLC project is created on the target system and loaded.

Call: PLC menu or TwinCAT PLC toolbar options or context menu of the PLC project object (<PLC project name>Project) in the Solution Explorer

Requirement: The PLC project is error-free and the target system is in Run mode.

Possible login situations:

Compiling the project before logging in

If a PLC project has not been compiled since its last change, TwinCAT compiles the project before logging in. This operation corresponds to the command Compile in logged-out state.

If errors occur during the compilation, a message dialog appears. The errors are displayed in the Error List view. You can then decide whether you want to log in without loading the program onto the controller.

See also:

Error on login

If an error occurs while logging on to the controller, TwinCAT interrupts the loading process with an error message. The error dialog allows you to display the error details. If an exception error has occurred and the text *SOURCEPOSITION* is contained in the log message, you can use the command Display in Editor to display the relevant function in the editor. The cursor jumps to the line causing the error.

Output of information on the loading process

If TwinCAT loads the project onto the controller when logging in, the following information is displayed in the message window:

Command Login 2:

In online mode, you cannot change the settings of devices or modules. To change device parameters, you must log the PLC project out. Depending on the bus system, there may, however, be some special parameters that you can change in online mode.

Command Login 3:

TwinCAT stores the view configuration separately for online and offline mode. In addition, views that cannot be used in an operation mode are closed. For this reason, the view may change automatically when you log in.