Siemens SIMATIC CP 340 User Manual page 174

Connecting Cables
B.2 20 mA TTY interface on the CP 340-20mA-TTY
Block diagram
The figure below shows a block diagram for a 20 mA TTY interface IF963-TTY.
Figure B-8
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.
Please note that you must only use shielded connector casings. A large surface area of both
sides of the cable shield must be in contact with the connector casing. You are advised to
use Siemens V42 254 shielded connector casings.
Never connect the cable shield with the GND, as this could destroy the interface modules.
In the following
On the following pages you will find examples of connecting cables for a point-to-point
connection between the CP 340-20mA-TTY and S7 modules or SIMATIC S5.
174
Block diagram for the 20 mA TTY interface IF963-TTY
CAUTION
PtP coupling and configuration of CP 340
Manual, 04/2011, A5E00369892-03