System Rapid Link
01/08 AWB2190-1430GB
12
Head station
The interface control unit RA-IN head station provides the
connection to the PROFIBUS-DP field bus and handles all
communication within the AS-Interface
®
run.
The user program receives its input information from the interface
control unit RA-IN. To the outside, the overall system acts like a
single connection cable. In the higher-level fieldbus the interface
control unit RA-IN is a station with its own address.
The interface control unit RA-IN contains a built-in power extender
(PEX) with a data link for up to 2.8 A at 30 V
H
AS-Interface
®
voltage. The AS-Interface
®
power extender is current-limited (self-
resetting time-lag fuse, 3 A).
For the power supply of the interface control unit RA-IN, a standard
PSU with 30 V
H
to AS-Interface
®
specifications (SELV, smoothing,
etc.) with or without data link is needed. Each PSU can supply
several interface control units RA-IN. Power supply cables can be
standard round cables with 3
x
1.5 mm
2
or 3
x
2.5 mm
2
. The
length of these cables are not included in the permissible 100 metres
length of the AS-Interface
®
busbar run.
Cable lengths and voltage drop
When defining the length of the AS-Interface
®
line, observe the
following:
• Te maximum expansion, including all spur lines and M12 plug
lines of the function modules (for each assembled 0.5 m long
cable with M12 plugs, calculate 0.9 m), is 100 m. The cable
between PSU and RA-IN is not included in these 100 m.
• Each slave must be supplied with at least 24 V
H
+10/–15 %.
• The interface control unit RA-IN must be supplied with at least
26 V
H
.
Calculate the current demand and voltage drop to ensure that all
sensors, actuators and the interface control unit RA-IN receive the
required voltage.
Length of AS-Interface
®
data cable:
The rule of thumb for the length of the AS-Interface
®
data cable
with 1.5 mm
2
depending on the voltage of the interface control
unit RA-IN is:
• AS-Interface
®
voltage > 28 V: 80 m cable length
• AS-Interface
®
voltage > 26 V: 60 m cable length
Voltage at interface control unit RA-IN:
The voltage at the interface control unit RA-IN depends on:
• The length of the supply cable between PSU and RA-IN
• The cross-section of the supply cable between PSU and RA-IN
• the current consumption
Cable length between PSU and RA-IN:
The cable length between PSU and interface control unit RA-IN 8
is calculated from the voltage drop.
Voltage drop
D
U
=
Length l
x
current I
x
2
[V]
Conductivity
κ
x
cross-section A
Length l =
Voltage drop
D
U
x
conductivity
κ
x
cross-section A
[m]
2
x
current I
Conductivity of copper:
κ
=
57 m
O
mm
2
RA-…
U
f
26 V
Round
conductor
RA-IN
F
2,5 mm
2
RA-…
U
f
26 V
f
24 V
Power
supply
30 V
H
Round
conductor
RA-IN
F
2,5 mm
2
RA-…
RA-…
U
f
26 V
Round
conductor
RA-IN
1 m
F
2,5 mm
2
Figure 5:
Design of a data bus
Summary of Contents for Rapid Link
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