There seems to be two questions from the OP.
1. Set up of the HW interrupt for a DI module.
2. Simulation of OB40 interrupt with PLCSIM
L D 's post and screen capture shows the setup of the interrupt
For the OP, the operation of the digital interrupt is described in chapter 3 of this manual:
http://support.automation.siemens.com/WW/view/en/8859629
Check figure 3-6.
The triggering of OB40 in PLCSIM, is
Execute Menu - > Trigger Error OB -> Hardware Interrupt (OB40-47. In the dialog box that appears, from what the OP indicated, use 0 as the module address and 2000 as the POINT_ADDR (I think). This will simulate a OB40 for his DI module.
Thats my understanding, and my 2 cents.