Change small C program

I have this program in vc6 that sends command to a hardware port. The program is used to send a 12/24v signal to open a Cash Drawer with the help of inpout32.dll. I have managed to change the code myself, so the system sends the correct signal to the correct port, but I'm not able to get it to stop sending the signal, so it's not possible to close the cash drawer. (The system sends the 12/24v signal continuously. I've verified this by unplugging the cable, and the drawer closes just fine when the cable is unplugged. However, if I put the cable in again it opens right away. So I need to send the correct signal to stop sending the signal, or to "Reset" the port in a way so it stops sending the signal. Attached are the vc6 source. The manual for the hardware says this; To Open Drawer1 (GPIO 7) Write "0"h to I/O space register "50C" Bit 7 To Close Drawer1 Write "1"h to I/O space register "50C" Bit 7 Just ask if there are any questions.