CIF 3

CIF 3 event disabler

The CIF 3 event disabler tool can be used to disable certain events of a CIF 3 specification, or even to disable events not currently present in a CIF 3 specification. The tool has various options that can be used to control the working of the tool, and influence its output.

Usage scenario

Assume a system with some sensors and actuators. From the view of the supervisor (or controller in general), the sensors are uncontrollable, and the actuators are controllable. Now assume a controller is being designed for this system, and it is to be merged with a simulation model of the uncontrolled system, that is being designed as well.

The situation may arise that the controller only controls a part of the uncontrolled system. This may for instance be the case if the designer of the controller starts with a small controller and incrementally extends it to cover more and more functionality of the system. The designer may have already made a full simulation model of the uncontrolled system beforehand. Alternatively, if one designer develops the controller and another develops the simulation model of the uncontrolled system, the simulation model may be finished well before the controller for the entire system is finished.

A problem arises when a controller that controls only part of the system, is merged with a simulation model of the entire uncontrolled system. In the uncontrolled system, the actuators can usually be turned on and off arbitrarily, as they are not yet controlled in any way. If the controller doesn’t control certain actuators, the behavior of those actuators is not restricted, and during simulation the events to turn the actuators on and off can happen at any time. Events are urgent, that is, they take precedence over passage of time, and thus happen ‘immediately’. Events that are always enabled thus prevent passage of time. The simulation will turn the actuators on, off, on again, off again, etc.

To solve this problem, the controllable events of the uncontrolled system that are not restricted in any way by the controller need to be disabled. The CIF 3 event disabler tool makes this possible.

This is however not the only usage scenario. The same controller may be used for implementation. For the implementation, a mapping from events to variables that represent the I/O ports may be needed. This mapping could be a CIF specification, with an automaton that performs the mapping. Similar to having a complete simulation model, a complete mapping specification for the implementation may be available. If in such mappings the actuator events are always enabled, this may lead to similar problems as for the simulation, if the controller only controls part of the system. Here too, the event disabler can be used to restrict such actuator events from causing trouble.

Starting the tool

The tool can be started in the following ways:

  • In Eclipse, right click a .cif file in the Project Explorer or Package Explorer and choose CIF miscellaneous tools –> Disable events of CIF specification....
  • In Eclipse, right click an open text editor for a .cif file and choose CIF miscellaneous tools –> Disable events of CIF specification....
  • Use the cif3evtdis tool in a ToolDef 2 script. See the scripting documentation and tools overview page for details.
  • Use the cif3evtdis command line tool.

Supported specifications

The event disabler supports a subset of CIF specifications. The following restrictions apply:

  • Component definitions and component instantiations are not supported.

Preprocessing

No preprocessing is currently performed by this CIF to CIF transformation. To increase the subset of specifications that can be transformed, apply the following CIF to CIF transformations (in the given order):

Options

Besides the general application options, this application has the following options:

  • Input file: The absolute or relative local file system path to the input CIF 3 specification. If we relate this to the above usage scenario, the input file should be the controller that only controls part of the system.
  • Output file: The absolute or relative local file system path to the output CIF 3 specification. If not specified, defaults to the input file path, where the .cif file extension is removed (if present), and a .disabled.cif file extension is added.
  • Event names: The absolute names of the events. How these supplied events are used depends on the Event usage option. Multiple events may be specified, separated by commas and/or spaces.
  • Event names file: The absolute or relative local file system path of a file with the absolute names of the events. How these supplied events are used depends on the Event usage option. Multiple events may be specified in the file, on separate lines. Empty lines are ignored. Lines starting with a # character are ignored as well, and can thus be used to add comments.
  • SVG input events: Enable this option to use the SVG input events. How the events are used depends on the Event usage option.
  • Event usage: This option can be used to specify how the supplied events are to be used. That is, it specifies which events to disable. See the Specifying the events to disable section for more information.
  • Include input specification: Should the output file contain only the new automaton that is created to disable the events, or should it include the input specification as well? See the Output section for more information.

At least one of the Event names, Event names file, or SVG input events options must be used to supply events to the tool. It is allowed to use multiple of these options, to combine events from multiple sources, and supply all of them to the tool.

Specifying the events to disable

The Event names, Event names file, and SVG input events options can be used to supply events to the tool. How these events are used (or interpreted) depends on the Event usage option. Several alternatives are available:

  • Disable the supplied events, regardless of the alphabet of the input specification (disable)
  • Disable all supplied events, that are not in the alphabet of the input specification (alphabet)

The texts between parentheses at the end of the alternatives indicate the command line option values that correspond with the alternatives. The default is alphabet.

The most straightforward alternative is to manually specify the events to disable (the first alternative in the above list). The supplied events are then disabled.

Manually specifying the events to disable can be cumbersome. Especially if the controller is developed incrementally, this can be a burden. The more events the controller does restrict, the less events should be disabled using the event disabler. In this case it may be easier to list the controllable events of the uncontrolled system that the controller may or may not restrict. That is, the alphabet (the second alternative in the above list) of controllable events of the uncontrolled system is specified. Supplied events that are not in the alphabet of any of the automata of the input specification, are disabled.

The following table summarizes which events get disabled by the tool:

Event usage Event supplied Event in alphabet Event is disabled by tool
disable yes yes/no yes
disable no yes/no no
alphabet yes yes no
alphabet yes no yes
alphabet no yes/no no

Output

If the Include input specification option is enabled, the output specification is a copy of the input specification, which is then modified to disable certain events. For events that are disabled by the tool, but did not exist in the input specification, an event declaration is added. If the option is disabled, the output specification starts empty. For all events are disabled, an event declaration is added. Event declarations are added in their proper scopes, based on their absolute names, by adding groups around them as needed.

By default, the Include input specification option is disabled. This ensures that the output specification is small. The typical scenario is to merge the input specification, event disabler output specification, and simulation model together using the CIF merger tool. Disabling the Include input specification specification option then gives the best performance for the tool chain.

If any events are disabled by the tool, a new automaton is created, and this automaton is added to the output specification. The automaton is named event_disabler, but may be renamed if it conflicts with an already existing object with the same name. The automaton has no supervisory kind, and has the disabled events as alphabet. It has a single nameless location, with a single self loop for all of the events that are disabled. The guard of the self loop is false, which results in the events being globally disabled.

If the Include input specification option is enabled, and events are disabled that did not exist in the input specification, event declarations are added to the output specification for those events. If the Include input specification option is disabled, event declarations are added for all events that are disabled. Event declarations that are added and existed in the input specification (in case the Include input specification option is disabled), inherit their controllability from the input specification. All other events that are added are declared as controllable events if their name starts with c_, are declared as uncontrollable events if their name starts with u_, and are declared as neither controllable nor uncontrollable otherwise.