Siemens SIMATIC ET 200SP System Manual page 46

Installation
4.4 Installing BaseUnits
Installing a BaseUnit
Watch the video sequence (http://support.automation.siemens.com/WW/view/en/95886218)
To install a BaseUnit, follow these steps:
1. Install the BaseUnit on the mounting rail.
2. Swivel the BaseUnit backwards until you hear it click into the mounting rail.
3. Slide the BaseUnit parallel to the left until you hear it click into the preceding
CPU/interface module or BaseUnit.
Figure 4-4
46
Installing a BaseUnit
Distributed I/O system
System Manual, 12/2015, A5E03576849-AF