Rockwell Automation 1756-L6x_L7x ControlLogix System User Manual - Manual (Page 57)

Rockwell Automation Publication 1756-UM001O-EN-P - October 2014 57
Start Using the Controller Chapter 3
4. Select your controller and click Update Firmware.
5. Select the firmware revision to upgrade to and click update.
6. Click Yes.
The firmware upgrade begins.
1756-L6x Controller with Ethernet Driver
1756-L7x Controller with USB Driver