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AR# 22658

XST - "ERROR:Xst:2035 - Port <signal> has illegal connection. Port is connected to input buffer and following ports Port <pin> of instance <instance> with type <typename>"

Description

Keywords: XST, IBUF, OBUF, netlist

When attempting to instantiate a netlist, the following error occurs in XST:

"ERROR:Xst:2035 - Port <signal> has illegal connection. Port is connected to input buffer and following ports:
Port <pin> of instance <instance> with type FDCEC"

Solution

This error will occur if the instantiated netlist contains I/O ports. There are two ways to fix this error:

1. Generate the instantiated netlist without I/O ports.
2. Instruct XST not to add I/O Buffers.

Please refer to the XST User Guide on how to disable the automatic I/O Buffer insertion.
AR# 22658
Date Created 01/09/2006
Last Updated 04/11/2007
Status Active
Type General Article