And this issue is well known and your PID formulation expectation depends from which area you come. Process control people like the "integral time" while mechatronics uses "integral gain". Since we have a so large base of customers, we created this VI that helps you convert from one type to another:
http://zone.ni.com/reference/en-XX/help/370401H-01/lvpid/pid_structure_conversion/
Here is the manual:
http://zone.ni.com/reference/en-XX/help/370401H-01/
http://zone.ni.com/reference/en-XX/help/370401H-01/lvpidmain/pid_topo/
Barp - Control, Simulation, RTT and HIL - National Instruments