Siemens SIMATIC S7 System Manual page 751

AS-Interface terminals
The removable terminal for connecting the AS-i cable is located behind the lower cover on
the front of the AS-i master CM 1243-2.
If the AS-i shaped cable is used, you can recognize the correct polarity of the cable by
means of the symbol
Information on how to remove and re-install the terminal block can be found in the system
manual "SIMATIC S7-1200 Programmable Controller" (Order No.: 6ES7298-8FA30-8AH0).
NOTICE
Maximum current carrying capacity of the terminal contacts
The current carrying capacity of the connection contacts is max. 8 A. If this value is
exceeded on the AS-i cable, the AS-i master CM 1243-2 must not be "looped in" to the AS-
i cable, but must instead be connected via a spur line (only one connection pair assigned
on the AS-i master CM 1243-2).
You will find additional information on connecting the AS-i cable in the section "Installation,
connection and commissioning of the modules" in the manual "AS-i Master CM 1243-2 and
AS-i data decoupling unit DCM 1271 for SIMATIC S7-1200".
Terminal assignment:
Label
ASI+
ASI–
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
.
Meaning
AS-i connection – positive polarity
AS-i connection – negative polarity
Functional ground
Technical specifications
A.10 Communication interfaces
751