How can I update a 'CAN Pack' to show the correct inputs via the command line?

First of all the same question was asked here and the MathWorks Support Team postet a script to update CAN Pack blocks, after changing the dbcFile via the command line. But I want to know which commands are used.

If I open a CAN Pack block parameter dialog box manually and close it by pressing OK, everything works fine. But if i use the commands

 open_system('mymodel/CANPack','mask')
 close_system('mymodel/CANPack')

the block does not update. Setting the saveflag doesn't work as it returns the Warning: Subsystems cannot be saved using save_system. Do I have to use another command to close the dialog box to update it?