What will happen if an input of DI card for AI card is connected inadvertantly with 220VAC
this test is going to be performed ? or realized already ? :) it's easy to conclude if smoke comes out or module color changed to black then card is blown if not isolators are working. ;) Jokes apart.
In general for digital modules there are isolators/barrier/fuses to restrict any entrance of high voltage, but the tolerance depends on duration of high voltage applied and the current and voltage level. Check specification for specific module.
Incase of Analog module, signal passes first through signal conditioner, A/D converters and there is channel to channel isolation or group isolation, so again check for module specification.
In case of DI/AI usually DC voltage is is given, and for AC voltage there are module type. Bytheway for which specific module type you have this question?