I deleted my first answer due to not understanding the question.
The CTU should work with UINT, INT, WORD. Check the help - it says what is supported. I don't think longs are, though (may be wrong)
Thank you for your answer, In the help it says the following
Function block Incrementer (CTU):
The input variables CU and RESET as well as the output variable Q are type BOOL, the input variable
PV and the output variable CV are type WORD
Also in the first chapters of the help, they mention that the size of type WORD variable is 16bit means it's max is 65535.
Am I reading the help wronge ?