MATLAB: ‘PID Controller’ in library ‘simulink_​need_slupd​ate’, error while trying to run old Simulink Code

Question

Hi,

I'm trying to run an old Simulink code and I'm getting the error:

Failed to find 'PID Controller' in library 'simulink_need_slupdate' referenced by '…/PID Controller1'.

I checked the library 'simulink_need_slupdate' on several different versions of MATLAB and could not find the PID controller in there.

My idea is to replace all of these blocks with a PID controller, and see if the code runs, the only problem is that I don't know the gains which were used in the old blocks, and I'm not sure if this will actually fix the code and there are several (~50) PID controllers to be replaced.

In the Simulink code itself the blocks show up as bad links, because the 'Source Link' shows up as 'simulink_need_slupdate/PID Controller'.

Any advice? Should I just replace all the PID's and try to recalculate the gains, or is there another easier path? Thanks for any help!

JR

Answer 1

It looks like your model has been made in an old release (before ~R2009), then open and saved in a recent release. But now you are trying to reopen it in an old release.

The PID block is in the "simulink_need_slupdate" library since R2010a or R2010b. The reason is that this old PID block has been replaced by a new PID block (<http://www.mathworks.com/help/toolbox/simulink/slref/pidcontroller.html>)

Before, it was inside the Simulink Extras library (I think the exact name is simulink_extras.mdl, please verify)

What you can do is write a script to find the problematic blocks using FIND_SYSTEM, then use SET_PARAM on these blocks to modify the "ReferenceBlock" property and point to the right place. (see http://www.mathworks.com/help/toolbox/simulink/slref/f23-7517.html for all the block parameters)

Please cnmtact technical support if you need help with that, your are not the first to encounter this situation.