Description:
In PAC-Designer's LogiBuilder sequencing language, the BEGIN SHUTDOWN instruction functions primarily as a passive label, with statements before it created in an 'interruptible' state, and statements following created in a 'non-interruptible' state. The statement itself is allocated a single state and requires one PLD clock cycle (4us) to execute. It is possible to over-ride this convention and manually specify individual instructions as interruptible (or not) by checking the option in their respective dialog boxes.
Solution:
Do perform any instruction in the 'shutdown' section of the program. No special or 'hidden' operations are performed regarding the analog-digital converter (ADC), digital-analog converter (DAC) or I/O as a consequence of executing the shutdown sequence.
The program only affects the logic written into the PLD portion of the device. The outputs are not set or reset automatically as a result of the shutdown sequence - you must set them to appropriate values manually with the 'output' instruction or similar functions you specify as part of your Logibuilder program before the program reaches its final end-of-program HALT.