Install the PC-80 software driver. The Edirol PC-80 includes a Mac-compatible installation disc, equipped with the necessary driver to achieve communication between your PC-80 and your Mac. If you fail to install the driver, you will have very limited MIDI capabilities. If you no longer have the disc, you can download the driver from Roland.
Check the MIDI configurations in your recording software. In order to achieve a MIDI connection, you must open a recording program such as GarageBand, Logic, QTractor, Cubase or another Mac-compatible audio/MIDI program. With your software open, select your "Options" or "Preferences," found among your menu bar options, select your "Input" options and select "Edirol PC-80" as an input device.
Create a MIDI track on your software window. Simply opening the software is not enough to transmit MIDI. You must also create a recording track designated specifically for MIDI input. Select the "New Track" option, which sometimes appears on the software window (such as in GarageBand, which comes standard with OS X Leopard and Snow Leopard), and sometimes among your menu bar options. When creating your track, select the option that reads "MIDI Track," "Instrument Track," "Virtual Track" or "Software Track."
Connect your PC-80 to a different USB port. The PC-80 does not use an AC adapter, and therefore relies on the USB port for power. As a result, you will not achieve a connection if you connect to a poorly-powered USB port. Do not connect the PC-80 to the USB port on your Apple keyboard, or to a port on an external USB hub. Connect directly to your computer, and try connecting to a second USB port if the first fails.
Check your MIDI cable connections. If you choose to interface your PC-80 to your computer using a traditional MIDI cable and an external sound card (audio interface), rather than the USB connections, make sure that you have your MIDI cable connected to the appropriate jacks. In order to transmit MIDI notes from the keyboard to your computer, you must connect your MIDI cable to the "MIDI In" jack on your adapter or audio interface (the keyboard itself has only one MIDI jack). If a connection still fails, try using a different MIDI cable, as your first cable may have a short circuit.