vs | plus in the control unit
A control unit is required for vs | plus to run. This can be a control unit in the conventional sense, i.e. a control unit on the road that regulates a intersection. However, there are also software control units that run on a PC. For vs | plus, the environment in which it runs is irrelevant. The following description is valid for a control unit on the roadside or a control unit that works together with a simulation programme.
Figure 1: vs | plus and the controller
vs | plus core: The vs | plus core is the control centre. The core communicates with the control unit via a defined interface (1). This interface is tested and certified by vs | verkehrssysteme ag. This ensures that every vs | plus delivers the same result with the same data, regardless of its environment.
vs | plus param: The vs | plus core requires parameters in order to control (2). These parameters are decisive for control with vs | plus. It is not necessary to be able to programme. To get a vs | plus control system up and running, you need the knowledge of a traffic engineer and not a degree in computer science. To extend the standardised and parameterised control system created with vs | plus, there is a special interface to the vs | plus core, called open vs | plus. This enables vs | plus to intervene in the standardised process.
Module: The vs | plus core is supported by various modules (3). These modules have the task of preparing data so that it can be processed in the core. An example of such a module is the evaluation of serial telegrams.
In a control unit in which vs | plus is running, the tasks are clearly organised. Each part does what it does best.
Control unit: It evaluates the detectors and receives the serial message points (4). The raw data is processed at the detectors. For example, the number of rising edges is counted, how long the detector has been occupied, how long the gap is (no longer occupied), etc. These aggregated values are transferred to vs | plus via the interface. The switching commands for the signal groups are sent from vs | plus to the control unit via the interface (5). In this case, vs | plus only sends the commands for free (green) and close (red). The transitions are switched by the control device according to the existing definition.
vs | plus core: In most cases, the vs | plus core is called once per second. With powerful control units, the call can also be made several times per second. The observer uses the information from the control unit to analyse what is currently running at the intersection. Are there new requests, is the green light extended, are the switched signals already in the desired state, etc.? After this situation assessment, the vs | plus control unit decides what should happen next. If something needs to be changed, the control unit sends commands (switching commands for the outputs) to the control device.
Analysing the inputs
Figure 2: Inputs and their processing for vs | plus
The parallel detectors connected to the control unit must be processed for vs | plus, as explained above. The required data is generated from the rising and falling slopes. The data is tracked in real time and made available to vs | plus. The same applies to the receipt of serial telegrams from public transport vehicles.
Figure 3: Switching the outputs after a vs | plus command
There are no signal groups or digital outputs in vs | plus. All outputs are modelled in vs | plus by display elements. When the control device receives a switching command, it must decide whether it is a digital output. In this case, the command is executed without a check. If it is a signal group, however, further checks are necessary. vs | plus sends the switching commands to the device at the correct time. This means that if the switching command comes from vs | plus, the signal can also be switched. This is checked again on the control unit and compared with the intergreen time matrix, which is supplied in the control unit. The set transition times must also be controlled. The signals are only switched when everything is correct. This additional check of the intergreen times at the control unit level provides a second level of safety when switching the signal groups.