Why do I receive a missing S-function error when upgrading my model containing Fixed-Point blocks from Simulink 5.1 (R13SP1) to Simulink 6.0 (R14)?

I have built my model using Simulink 5.1 (R13SP1) and am using the "Fixed Point Blockset - Sum" block from the library

 fixpt_lib_3p1/Math

The implementation of the block involved the S-function "sfix_add". I have since upgraded to Simulink 6.0 (R14) where the block was unified with the Sum block from the main Simulink library. When I build my model, I receive the following error.

 Error using ==> rtwgen

 Error in S-function 'MWsum_block/RemoteSum': S-Function 'sfix_add' does not exist.

I had broken the library links in my model and do not wish to replace each block with its updated version manually.

Answer 1

[MathWorks Support Team]

The design in Simulink 6.0 (R14) automatically maps the old fixed-point blocks to their new replacements when the model is loaded. Blocks with broken links typically do not give any trouble until the model is used with a newer version of Simulink. When used with a newer version of Simulink, however, blocks with broken links often cannot be used without repair.

You may use the MATLAB command

slupdate(gcs);

to automatically correct all the broken links for the old Fixed-point blocks.