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AR# 15429

6.1i Floorplanner - The net interconnect (Rubberband/Ratsnest) for IOB DFFs and DIFF BUFG is not displayed in the Floorplanner window


Keywords: Floorplanner, Ratsnest, rats nest, Rubberband, rubber band, IOB, DFF, flip flop, flip-flop, FF, differential, I/O, IO, connect, 5.1i

Urgency: Standard

General Description:
When I open a placed design in Floorplanner and select a component, the net interconnect (Rubberband/Ratsnest) is not displayed in the Floorplanner window.



The net interconnect is not displayed because the initial setting for the Rubberband/Ratsnest display property is turned off. To turn on the Rubberband/Ratsnest display:

1. Go to Edit -> Preferences and select the Ratsnest tab.
2. Select the "Rubberbands" option to turn on the Ratsnest display.


Floorplanner cannot show the connection between the component and the IOB if the IOB contains any of the following components:
- A differential buffer
- Registers

To view the connection, you must first place the components that cannot be placed by the Floorplanner. This occurs because of a bug that affects the Floorplanner's ability to display components in the IOB; only the pad component is placed.

Floorplanner displays differential buffers and DDRs in IOBs in the latest 5.2i Service Pack available at:
The first service pack containing the fix is 5.2i Service Pack 2.

NOTE: Displaying registers in IOBs is scheduled to be available in a future software release.
AR# 15429
Date Created 08/19/2002
Last Updated 02/21/2007
Status Archive
Type General Article