When you're attaching the hardware for your receipt printer to the computer, you should also hook up the cash drawer. The end that looks like an old school phone cable (smaller connector) goes into the back of the printer. The end that looks like an Ethernet cable (larger connector) goes into the bottom of the cash drawer.
Don't share cash drawers between multiple computers. While it can be accomplished by using a printer shared across the network, this setup makes your cash reconciliation process less reliable, makes cash discrepancies impossible to investigate, and prevents accurate reporting.
Troubleshooting the cash drawer
Most cash drawers issues are actually caused by your receipt printer! After you take a payment, Ascend gets the trigger to print a receipt and then gets the cue to pop the cash drawer open. If something goes wrong with the receipt being printed, then the trigger for the cash drawer is never sent.