I have just purchased an Epson XP-510 wireless printer, which I have set as the default printer on my MAC Pro. However my MAC keeps telling me that the printer is off line yet my iPad prints away merrily. Has anyone any idea what's missing?

Hello Ricky,

It sounds like you are not able to print to your Epson XP-510. I found an article with steps you can take to troubleshoot printer issues on a Mac:

Follow these steps until the issue is addressed:

1. Make sure that the printer is powered on, has ink / toner, and that there are no alerts on the printer’s control panel. Note: If you cannot clear an alert on the printer's control panel, stop here and check the printer's documentation or contact the manufacturer for support.
2. Ensure the printer is properly connected to a USB port on the Mac or AirPort base station / Time Capsule. If the printer is a network-capable printer, make sure that it is properly connected to your home network.
3. Use Software Update to find and install the latest available updates. If an update is installed, see if the issue persists.
4. Open the Print & Scan pane or Print & Fax (Snow Leopard) pane in System Preferences.
5. Delete the affected printer, then add the printer again.

If the issue persists, try these additional steps:

1. Reset the printing system, then add the printer again.
2. If the issue still persists, reset the printing system again. Download and install your printer's drivers. Then, add the printer again.
3. Contact the printer vendor or visit their website for further assistance.

Additional Information

Note: If your printer is wireless-capable, you should first add the printer to your network. Use the printer's control panel, or temporarily connect the printer to your Mac via USB. For more details, see this article.

You can find the full article here:

Troubleshooting printer issues in OS X

http://support.apple.com/kb/TS3147

Thank you for using Apple Support Communities.

Best,

Sheila M.