HP Deskjet 6540 Color Inkjet Printer - Manual (Page 166)

Note: Do not press the buttons on either side of the duplexer when installing
it in the printer. Use the buttons only when removing the duplexer from
the printer.
10.1.2 Enabling the duplexer
Follow these step to enable the duplexer:
1. Open the printer Toolbox .
2. Click the Configuration tab.
3. Click Automatic Two-Sided Printing Module , and then click Apply.
4. Click OK in the confirmation box that appears.
5. Click the X in the upper-right corner to close the screen.
Note: After the duplexer is enabled, it is not necessary to re-enable it every time
you print.
10.1.3 Printing a booklet automatically
To print a booklet automatically, one of the following accessories must be attached
to the printer:
Automatic Two-Sided Printing Accessory
Auto Two-Sided Print Accessory with Small Paper Tray
HP Deskjet 6500 series printers
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