PLC counterup and counterdown

Sir yaha pe Jinta object in ho rahe utne object dispatch ho rahe toh (warehouse full) yani stop output kyu mila he ??

CTU
Preset 500
Accum 500 means 500 object in hua

CTD
Preset 500
Accum 500 means 500 object dispatch hua

Tohh stop kyu high hoga
Aapne explain kiya he ki jab warehouse full hoga tabhi stop high hoga …
Plzz explain