Echelon ISI - Manual (Page 101)

99 ISI Programmer’s Guide
IsiTick(), because using these functions causes the linker to include the more
specific functions (including the DAS functions) with the application.
If your application uses the CENELEC Configuration Library functions to enable
or disable the CENELEC Media Access protocol at runtime, your ISI application
does not need to link with the cenelec.lib library because the PL 3170 system
image includes these functions.