Specifications

AS-Interface
System components and accessories
Extension plugs
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Siemens IK PI · 2009
6
■ Design (continued)
Topology of an AS-Interface network with a size of 200 m
The extension plug / extension plug plus is connected using an
M12 plug-in connection and most easily realized with the help of
the 3RX9 801-0AA00 AS-Interface M12 feeder to IP67 degree of
protection.
Depending on the size of an AS-Interface segment and the
power consumption (the power consumption varies with the
number of stations connected), it is important to make sure that
the voltage drop along the AS-Interface cable does not become
excessive. To guarantee that even the remotest slave is still sup-
plied with the necessary minimum voltage, the extension plug
has a voltage monitor. With the extension plug, any undershoot-
ing of the minimum voltage in accordance with the AS-Interface
specification is clearly indicated by flashing of a green LED;
a correct AS-Interface voltage is signaled by steady illumination
of the green LED. The undervoltage detection has a delay for the
LED indication in order to recognize also short-time voltage dips
of the type which occur, for example, when actuators are
switched.
The extension plug plus is equipped with an AS-Interface slave.
Instead of the diagnostics LED, the extension plug plus commu-
nicates the diagnostics information directly to the AS-Interface
master. Two different voltage values can be set as threshold
value. Using two diagnostics bits it is possible to distinguish
between brief and lengthy voltage drops.
For particularly large AS-Interface networks the maximum possi-
ble cable length can be increased further by using repeaters.
Please note that when a repeater and an extension plug / exten-
sion plug plus are used together, the series connection of re-
peaters is not possible. Hence the maximum possible distance
from the master to a slave is 400 m and the absolute maximum
cable length is 600 m. The parallel connection of repeaters for
a star-shaped configuration with segments up to 200 m long
respectively is possible.
Maximum network size with repeaters and extension plug (master at center of network)
Master
Slave
100 m
200 m
Repeater
Power
Supply
SlaveSlave Slave SlaveSlave
Power
Supply
NSA0_00370a
100 m
Master
Slave
Power
Supply
SlaveSlave Slave SlaveSlave
Extension
Plug
with Repeater
with Extension Plug
200 m
600 m
Repeater
NSA0_00371a
200 m 200 m
Master
Slave
Power
Supply
Slave Slave Slave Slave Slave
Power
Supply
Power
Supply
Extension
Plug
Extension
Plug
Extension
Plug
Repeater