Output Enable Control of Lower Level Modules

Only equations that drive output pins in the top level file can have output enable control. If the equation does not drive a pin, the .OE control equation must be deleted.

For example, consider the following lower-level file:

sig_a = sig_1;
`` sig_a.OE = (1); ``Comment out this control equation
``because sig_a does not drive a pin in the top-level file.

sig_b = sig_2;
sig_b.OE = (1); ``sig_b drives a pin in the top-level file,
``and therefore the .OE equation remains unchanged

If the lower-level ABEL file contains an equation with OE control, and that equation does not drive a device output pin in the top-level file, the link process will fail and the following error message will be issued:

Logical Error 3512: Signal ___ in module ___ has an OE. An output wire is required for that signal.