Devices > Placement of a Device or Ground Device in a Slot

Optimized

Ground Placement

This is licensed functionality. If you do not have the appropriate license, optimized ground placement is not available. It occurs when there are multiple slots with “Place by Attribute/Property” constraints that match a ground device and at least one attached, non-ground device has been placed. Optimized Ground Placement takes into account variant placement of the attached non-ground devices as well as options on the ground slots, which may result in a single ground device being placed multiple times.

Considering this functionality at a high-level, when a device is variantly placed in the vehicle, it may be desirable to ground it at different points in each variant. In addition, some ground points may only be available in certain vehicle configurations (controlled by putting an option on a slot).

The following is a low-level, detailed description of the steps that optimized ground placement follows:

Identifies the number of placement contexts that are required This is done by considering the variant placement expressions on the attached devices as well as the options on all slots that match the ground device. Each placement context is a unique combination of the variant placement expressions, but unsupported combinations (exclusive options or options that cannot appear together) are ignored. If there are no variantly-placed, attached devices and no options on the matching ground slots, there is a single placement context.
Variant placement of ground devices For each placement context, it is necessary to place the ground device once at most: The activeness of the attached device pins is determined by applying the placement context. The system assumes any unconsidered options on the functional device pins to be true. For example, options not in variant placement expressions or on the ground slots. In other words, a device pin is considered active unless it has been explicitly set as inactive by one of the options in the placement context. If none of the attached devices is active, the placement context is skipped.

The optimal ground position is determined using wiring synthesis. However, since there is a context for this, no routing through non-applicable bundles occurs and the ground device is not placed in a non-applicable slot. Exclusive option relationships are used to determine this applicability.

Once the optimal ground slot is found, the ground device is placed using the placement context as its variant placement expression.

Placement then moves on to the next placement context. If the ground device is placed in a slot where it has already been placed for a previous context, the placement Option Expressions are combined using OR and are simplified.

For example:

Ground device G1 is connected to a non-ground device DEV1. DEV1 has a logical option expression of ABS.

DEV1 is variantly placed as LHD and RHD. LHD and RHD are marked as mandatory exclusive.

There are three matching ground slots with options LHD, RHD and ‘none’ (that is, a slot with no option expression).

The placement contexts are calculated as unique, supported combinations of the variant placements and ground slot options. Therefore, the contexts are LHD and RHD.

Placement places the ground device once at most for each context LHD and RHD.

For the first placement context LHD:

The placement of the ground device is determined using the lowest cost algorithm. However, the system must use the placement context (so it must not route through a RHD bundle for example).

The optimal ground slot might either be LHD or ‘none’. In either case, the ground device is placed and tagged with the variant placement expression LHD.

For the second placement context RHD:

The optimal ground slot might either be RHD or ‘none’. There are several possibilities depending on where the ground device was originally placed:

If the optimal slot is RHD, the ground device is placed and tagged with the variant placement expression RHD.
If the optimal slot is ‘none’ and the original placement was in the LHD slot, the ground device is placed and tagged with the variant placement expression RHD.
If the optimal slot is ‘none’ and the original placement was also in this slot, the ground device variant placement expression is changed from LHD to LHD||RHD.

Parent Topic:

Placement of a Device or Ground Device in a Slot