Omron E5EK PROGRAMMABLE TYPE User Manual page 30

CHAPTER 2 PREPARATIONS
J Mounting
2--6
(1) Insert the E5EK-T controller into the mounting hole in the panel.
(2) Fit the mounting bracket (accessory) into the fixing slots on the top
and bottom of the rear case.
(3) Tighten the two mounting bracket screws alternately a little at a
time until the ratchet starts to slide.