Management of missing variables in a signal bus

It is possible for users to extract signals (by typing their names in) which do not currently exist within the bus entering into a Bus selector component:

Figure 417: Missing inputs in bus selector

As shown in the figure above, the missing signals Ttyres, Hamb and Tcabin-rear are missing in the input bus. This scenario is usually undesirable to users, as it is equivalent to a system attempting to access data which does not exist. Consequently, a means of informing the user of cases where this arises in the sketch has been devised.

Indeed, when the user looks at the sketch, this component is now highlighted in yellow, signifying that missing signals are being extracted from the bus.

Figure 418: Selectors which are attempting to extract non-existent signals are highlighted in yellow

This highlighting will be applied to all components in the sketch which attempt to select non-existent signals:

Figure 419: Most subsystems in the sketch are attempting to extract missing signals from a non-existent controls bus.

The most common case where this occurs is that of library supercomponents containing Bus selector components. When this type of library supercomponent is shared and re-used in new models, the input bus with which the supercomponent is provided may not contain the signals expected at the selector.

An easy way of visualizing which signals are consumed by a given supercomponent (or any bus component) is to display its external variables. The External variables view has been adjusted specifically for buses, and now displays the text identifiers of their signals, as well as their status - whether they are used, unused or missing in any given case.

Warning

In the current version of Simcenter Amesim, it is not possible to encrypt supercomponents which contain signal bus ports.

Figure 420: A supercomponent containing bus selectors which are extracting missing signals

In the image above, the TCU component contains a signal bus selector, but its input bus does not contain some of the signals. The color code for the text identifiers is as follows:

• Black, normal: signal is consumed by the selector.

• Grey, italic: signal is not extracted by the selector.

• Red, bold: signal is extracted but is missing from the input bus.

Therefore, in the image above we can infer that all of the signals in the DriverCommands bus are available, of which DrivingCycleVSpeedMode1 and AccelCommand are extracted, whereas the entirety of the Commands bus is missing, in which members of the CAN and GUI sub-buses are currently being extracted.

Users can act on this information by either adjusting the input buses, or by adapting selector components so as to avoid extracting missing signals.

Note

It is currently possible to simulate models containing selectors which extract missing signals. This is highly inadvisable, and will result in the extracted signal taking a fixed constant value in the order of 10308. Please use extreme caution when simulating models containing missing signal extractions.