Connect your MIDI interface to your computer. MIDI interfaces come in two popular varieties: FireWire and USB. A FireWire interface requires a FireWire port on your computer: if your computer is not FireWire-ready, make sure your MIDI interface has a USB connection. Connect the USB cable to any available USB port on your computer. USB ports have an image of a trident above or next to them.
Connect a standard five-pin MIDI cable to any "MIDI-In" jack on the front of your MIDI interface. You can purchase a MIDI cable at any music supply store, as well as from many electronics retailers.
Connect the other end of the MIDI cable to any one of the "MIDI Out" ports along the back of your MPC. This connection will allow you to transfer MIDI signals from your MPC to your computer through your MIDI interface. In order to read the signals on your computer, you will need to open a digital audio program that reads MIDI data. Most commercial recording software and many freeware programs can read MIDI data.
Reverse the cable to send MIDI signals from your computer to your MPC through the MIDI interface: connect the MIDI cable to a "MIDI In" jack on the back of your MPC and to a "MIDI Out" jack on your interface. This will allow you to record MIDI data into your MPC, as opposed to sending data from the device.