Siemens SIMATIC S7 System Manual page 53

Note
Install expansion modules separately after the CPU has been installed. The CPU models
CPU CR20s, CPU CR30s, CPU CR40s, and CPU CR60s do not support the use of
expansion modules or signal boards.
Consider the following when installing the units on the DIN rail or on a panel:
● For DIN rail mounting, make sure the upper DIN rail clip is in the latched (inner) position
and that the lower DIN rail clip is in the extended position for the CPU.
● After installing the devices on the DIN rail, move the lower DIN rail clips to the latched
position to lock the devices on the DIN rail.
● For panel mounting, make sure the DIN rail clips are pushed to the extended position.
To install the CPU on a panel, follow these steps:
1. Locate, drill, and tap the mounting holes (M4 or American Standard number 8), using the
dimensions in the table, Mounting dimensions (mm) (Page 51).
2. Ensure that the CPU and S7-200 SMART equipment are disconnected from electrical
power.
3. Secure the module(s) to the panel, using a Pan Head M4 screw with spring and flat
washer. Do not use a flat head screw.
4. If you are using an expansion module, put it next to the CPU and slide together until the
connectors join securely.
Note
The type of screw will be determined by the material upon which it is mounted. You
should apply appropriate torque until the spring washer becomes flat. Avoid applying
excessive torque to the mounting screws. Do not use a flat head screw.
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
3.3 Installation and removal procedures
Installation
53