ero electronic LFS - Page 9

6
GB
INDUCTIVE LOADS
High voltage transients may occur when switching
inductive loads.
Through the internal contacts these transients may
introduce disturbances which can affect the
performance of the instrument.
The internal protection (varistor) assures a correct
protection up to 0.5 A of inductive component.
The same problem may occur when a switch is
used in series with the internal contacts as shown
in Fig. 10.
Fig. 10 EXTERNAL SWITCH IN SERIES WITH
THE INTERNAL CONTACT
In this case it is recommended to install an
additional RC network across the external contact
as shown in Fig. 10
The value of capacitor (C) and resistor (R) are
shown in the following table.
Anyway the cable involved in relay output wiring
must be as far away as possible from input or
communication cables.
SERIAL INTERFACE
RS-485 interface allows to connect up to 30
devices with one remote master unit.
Fig. 11 - RS-485 WIRING
The cable length must not exceed 1.5 km at 9600
BAUD.
The "serial comunication" and the "logic input"
options are mutually exclusive.
NOTE: The following report describes the signal
sense of the voltage appearing across the
interconnection cable as defined by EIA for
RS-485.
a) The ” A ” terminal of the generator shall be
negative with respect to the ” B ” terminal for
a binary 1 (MARK or OFF) state.
b) The ” A ” terminal of the generator shall be
positive with respect to the ” B ” terminal for
a binary 0 (SPACE or ON)
12
13
COMMON
11
B'/B
B/B'
A/A'
A'/A
M
A
S
T
E
R
I
N
S
T
R
U
M
E
N
T
LOAD
(mA)
<40 mA
<150 mA
<0.5 A
C
(µF)
0.047
0.1
0.33
R
(Ω)
100
22
47
P.
(W)
1/2
2
2
OPERATING
VOLTAGE
260 V AC
260 V AC
260 V AC
LFS-servo-1-02.p65 1/14/02, 3:43 PM6