Each sequential function chart can be configured to use one of the following Execution Modes :

• Callable
  This chart can be started via scripting or another chart's enclosing step on-demand. Any number of instances of this chart can be simultaneously running.

• RunAlways
  This chart can be started by the Gateway upon startup. It can not be executed in any other way. It is probable that this chart be designed to never end, the idea being that there will always be exactly one instance of this chart running.

• Disabled
  This chart is not available for execution.