Panasonic FP0 User Manual page 104

Installation
6.1 Adding Expansion Units
2. Raise the expansion hooks on the top and bottom sides of
the unit with a screwdriver.
3. Align the pins and holes in the four corners of the control unit
and expansion unit, and insert the pins into the holes so that
there is no gap between the units.
Control unit
4. Press down the expansion hooks raised in step 2 to secure
the unit.
6 − 4
Expansion hook
Expansion unit
FP0