how to create a display for counter output in hmi with ac450 controller with 800xa software
In this case, yes DAT(I) is the simple and easy answer. It will usually work quite well.
You can also use AIC and AOC elemments to display analog values. AIC is usefull of you want alarm handling and to be able to block and force values from the HMI ( remember to connect your calculation to the CALC_VAL terminal). AOC is usefull if you want to have AUTO and MANUAL settings of the value.
AIC and AOC also have trending enabled by default. However, if you want to trend a DAT element using TTD logs you must set the VALID terminal to TRUE.