ContactPanels can be used to interact with the bus as well as display streaming data from the bus for a multitude of purposes. For example, a dashboard can be designed that will report engine speed, gear position, and temperatures within the engine compartment. Additionally, through toggles and incremental sliders, you can make changes to the signal data on the bus to simulate real-time changes in conditions. To do this, panel elements have the ability to interact with both Signal data and a panel specific Environmental Variable.
Signals are a part of the CAN message and relay specific information pertaining to the message in which it is stored. Environmental Variables are data types that are not dependant on CAN messages and can be freely updated and changed in order to pass data between the Panel and the CAN bus.
To use an Environmental Variable, first one must be created in a CANoe database file through CANdb++. Once an EV has been created it can be associated to a Panel element. This element can now make changes to the value of the EV, and in turn through CAPL programming, the EV can be used to update Signal data and transmit back onto the bus.
While it is possible to assign a Signal to a Panel element in a similar manner to an EV, it is not recommended. Without specific Interaction Layer DLLs and database attributes, direct manipulation of Signals is not possible. It is, however, possible to use Signal data from the bus with Display Only Panel elements such as gauges and numerical outputs.