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AR# 37114

12.1 PACK - "ERROR:Pack:1560 - The register "xx" has the property IOB=FORCE, but was not packed into the OLOGIC component"


The following error occurs during MAP.

ERROR:Pack:1560 - The register "xx" has the property IOB=FORCE, but was not packed into the OLOGIC component. The output signal for register symbol c requires general routing to fabric, but the register can only be routed to ILOGIC, IODELAY, and IOB.

How can I resolve this problem?


This error occurs when the register to be packed into OLOGIC drives not only the output buffer but also the fabric logic.

The output pin of the Flip-Flop in the OLOGIC has a unique route to the output buffer and cannot be routed out of the IOB to the fabric logic.

As a result the register driving both the output buffer and the fabric is not able to be packed into IOB.

To resolve this problem, duplicate the register and have two registers driving the output buffer and fabric separately.

The register which drives the output buffer only can then be packed into the IOB.

For other reasons why the register can fail to be packed into IOB, please see (Xilinx Answer 35520).

Linked Answer Records

Associated Answer Records

Answer Number Answer Title Version Found Version Resolved
35520 11.5 PACK - What can cause an I/O register to fail to pack into an IOB, ILOGIC, or OLOGIC component? N/A N/A
AR# 37114
Date Created 07/29/2010
Last Updated 07/29/2014
Status Active
Type General Article