Devices

Combining Ground Devices in Selected Ground Slots

After you have placed some ground devices in ground slots and before you have routed signals, you can automatically combine ground devices located together in selected ground slots. This action enables the sharing of wiring between ground devices (that is, creating a “ground tree” of spliced wires).

If multiple harnesses are connected to ground devices, via unique slot connectors, you can combine the ground devices if they connect to the same harnesses.

Note

If you have placed ground devices in equipment slots instead of ground slots, then you must combine ground devices manually. See Combining Normal Devices in a Slot. If a ground device has a library part, it is not combined with other devices.

You can set the following constraints for slots so that the automatic combination of ground devices and the creation of multiple terminations follow rules: Ground Device Combination, Max Ground Slot Connector Cavities, Max multitermed Ground Signals and Multiterm Ground Devices. See Overview of Rules and Constraints for descriptions of these constraints. You must set a Ground Device Combination constraint before combining ground devices.

When the system combines ground devices automatically, the following points apply:

Ground devices with multiple signals do not merge their signals on a combined device but they can form multiple terminations.
Devices with part numbers are never combined.
If some ground devices are already combined before you perform this action, they stay combined regardless of any constraints that exist on any object in the design. You must unplace a device to un-combine it.
Slot connectors that are de-populated due to the combination of signals (multiple terminations) are not deleted.
Bundle connectivity is never changed.
The option expression on the combined device is the logical OR of the option expressions on the constituent logical devices. Also, the device is considered to be variantly placed using the logical OR option expression of the constituent placement option expressions. If at least one of the devices has no option expression or no variant placement, the resulting combined device is considered to have no option expression or no variant placement.

Note

The ‘Generate separate ground wiring for each combination structure’ project preference enables intelligent ground wiring synthesis that respects partial ground device combinations across variant configurations. When enabled (the default), it prevents unwanted wiring reuse between combined and non-combined ground devices. If disabled, the system reuses wiring regardless of ground combination status. See Handling of Ground Device Combinations in Wiring Synthesis for an example.

Procedure

Having placed ground devices in ground slots, select the slots in which you want to combine ground devices in the Design Browser (Design tab), press Space Bar and enter Auto-Refine Grounds. The system combines the ground devices automatically and displays the combined devices in the Design Browser (Design tab) with the original devices listed below the combined device. Signal mappings are re-balanced across existing slot connectors and their cavities taking into account the Max multitermed Ground Signals constraint. New cavities may be generated on existing slot connectors as a result of the constraint as long as the new cavity does not violate a Max Ground Slot Connector Cavities constraint. Once the maximum number of cavities is reached on a slot connector, the remaining signal are multi-termed regardless of any Max multitermed Ground Signals constraint. This may result in cavities having too many terminations because you cannot add more cavities to a slot connector.
Run the Ground device that breaks placement rule design rule check, this informs you of any cavities with too many terminations. Make changes to the design to fix these.

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Devices