Siemens SIMATIC ET 200SP Manual page 28

Connection
4.2 Schematic circuit diagram
If safety-related signals are to be processed on the AS-i cable, you can arrange a dark
BaseUnit type C1 to the right of the light BaseUnit type C0 with the CM AS-i Master ST
module and plug a safety-related F-CM AS-i Safety ST module onto this dark BaseUnit. The
AS-i cable is continued from the light BaseUnit to the dark BaseUnit via the power busbars
so that the F-CM AS-i Safety ST module is connected to the AS-i network of the master
without additional wiring.
It is not permitted to transmit the AS-i voltage from the connecting terminals on the front of
the dark BaseUnit because a current draw of this type may cause an overload in the
modules.
Connect the AS-i cable with AS-i power supply unit and AS-i slaves only to terminals 1L, 2L
(ASI+) and 1N, 2N (ASI-) of the light BaseUnit.
You can find additional information on safety-related processing in the "Fail-safe module
F-CM AS-i Safety ST (https://support.industry.siemens.com/cs/ww/en/view/90265988)"
manual.
Power supply units supported for AS-Interface
A connected power supply unit must have the following properties:
● Rated output voltage 30 V DC (AS-Interface Standard) or 24 V DC (AS-i Power24V)
● PELV/SELV (Protective/Safety Extra-Low Voltage) standard
● Residual ripple < 250 mVpp
● Limiting of output voltage to max. 40 V in the event of a fault
The Siemens power supply units for AS-Interface meet these requirements (see operating
instructions of the power supply unit).
Use an AS-Interface power supply unit (with integrated data decoupling) or a combination of
a standard power supply unit and a data decoupling module.
When AS-i Power24V is used, there are limitations on the cable length (max. 50 m
AS-i cable) and usability of AS-i components and connected sensors/actuators due to the
reduced voltage.
Additional notes:
● AS-Interface System Manual
(http://support.automation.siemens.com/WW/view/en/26250840/0/en)
● FAQ "Compatibility for AS-i Power24V"
(http://support.automation.siemens.com/WW/view/en/42806066)
Power supply
The CM AS-i Master ST is fully powered from the AS-i voltage. Only the internal backplane
bus interface for the ET 200SP station (including the DIAG LED) is powered from the
operating voltage of the ET 200SP station.
If the operating voltage of the ET 200SP station fails, the communication between the
AS-i master and AS-i slaves continues without interruption, in which case the outputs of the
AS-i slave are reset to zero.
28
AS-Interface master CM AS-i Master ST (3RK7137-6SA00-0BC1)
Manual, 07/2017, A5E02655262020A/RS-AD/004