Primary features of background task

The purpose of the background task is to monitor the status of the cell as a whole and to communicate with external devices.

Function BgMain, a function specified as the "Background task" will be automatically activated as task 65 when the controller starts and loads the project.

If another task is created within the background task using the XQT command, that created task will be assigned to task No.65 (and onward in the ascending order) and will also function as a background task. In addition, specifying a task type for an XQT command in a background task has no meaning.

An operator is not necessarily aware of the operating Background task which does not stop at the input of emergency stop or safeguard signal. The Background task will not stop when an operator inputs "PAUSE" or "ABORT".

In this sense, the background task functions for the application program to work as a part of the system.

On the other hand, the execution commands to operate the Manipulator, set-up commands for the Manipulator or the commands for image processing cannot be executed within the background task.

CAUTION

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• Specify Forced flags in I/O output commands operated from background tasks to enable On/Off of I/O outputs at the following times:

  During emergency stop, when safety door is open, in teach mode, or when an error occurs

• Do not connect external equipment that operates mechanically, such as actuators, to an I/O output that specifies a Forced flag. Doing so may cause external equipment to operate at the following times, which can be extremely dangerous:

  During emergency stop, when safety door is open, in teach mode, or when an error occurs

  Forced flag is designed to be specified for I/O outputs connected to external equipment without mechanical motion such as status display LEDs.