Problem: Canon PIXMA MX870 says “Set the PC to start scanning” when the “Black” or “Color” scan start buttons are pressed.

Solution: How I enabled one-button scanning

  1. Install most of the OS X drivers and software from canon.com. I think I installed all of the drivers, or at least ran their downloaded installers. As of this writing, that’s ICA Driver, CUPS Driver, Scanner Driver, Mini Master Setup. I also installed MP Navigator and IJ Network Tool from the software downloads. Reboot.

  2. After installing the “Canon IJ Network Scanner Selector,” a printer/scanner icon should appear in the dock. The installer sets up the app to run at startup, which I left enabled. The dock dropdown “Scan images using the operations panel of the scanner” option is enabled. The scanner MAC address is listed and selected in “Open Settings”:

  3. Run MP Navigator (3.1) and on the main menu, there’s an option in the upper right “One-click.” Mouseover it and a different menu will be shown, including a “Start scanning by clicking the button” checkbox. This was not the default. I wish I was making this up.

  4. On that MP Navigator One-click screen, click Preferences. Note that you may have 2 entries under “Product Name” (“MX870 Series” and “MX870 Series (Network: )." I disabled "Compress scanned images when transferring" for both product names. On the Scanner Button Settings screen, I changed the paths under "Save to PC" but didn't make any other changes.

  5. After making these changes, I was still seeing “Set the PC to start scanning” when I tried to scan. I shut down MP Navigator and restarted the printer (with the PC on) and it started auto-scanning. I didn’t restart the PC except after step 1. I’m not sure whether the problem was a one-time issue because the settings changed or a recurring one with the order that they were originally powered on.

Notes

Here’s the printer options from System Preferences. I didn’t make any changes: