Siemens SIMATIC CP 440 Manual page 155

Connecting Cables
If you make your own connecting cables, you must remember that unconnected
inputs at the communication partner may have to be connected to open-circuit
potential.
Note that you must only use shielded connector housings. A large surface area of
both sides of the cable shield must be in contact with the connector housing and
the shield contact. You are advised to use Siemens V42 254 shielded connector
housings.
Caution
!
Never connect the cable shield with the GND, as this could destroy the interface
submodules.
GND (pin 8) must always be connected on both sides, otherwise the interface
submodules could be destroyed.
In the Following
The following pages contain examples of connecting cables for a point-to-point
connection between the CP 440 and S7 modules or the SIMATIC S5.
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
Connecting Cables
B-3