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LED
Description Function
CTS
Clear to
send
DCD
Settings
The DIP-switch S1 establishes the mode of operation
of the modem.
Switch C-1 is reserved for future use. C-2 establishes a
permanent carrier on the line which is useful in a four-
wire fullduplex connection.
Switch 2-W distinguishes between two-wire and
four-wire operation of the modem. In two-wire mode
X3-1 and X3-2 form terminal NF1 which is used for
transmission and reception. In four-wire mode X3-1
and X3-2 form the transmitter terminal NF1 and X3-3
and X3-4 form the receiver pair NF2.
The next three switches belong to the transmitter
amplitude. In a long multi-drop line configuration,
where the modem in the central needs a high
amplification factor to receive the signal of the last
modem, the transmission level of the modem next to
the central station can be reduced by 20 dB with the
–20dB switch. This is done to avoid overdrive of the
receiver in the central station modem. To compensate
a low-pass character of the transmission line, the
amplitude of the upper transmission frequency can
be increased by 20 %, 40 % and 60 %. If both switches
20% and 40% are 'off', no increasing of the amplitude
takes place.
The 500FSD10 has five predefined receiver
amplifications: 0 dB, 10 dB, 20 dB, 30 dB and 40 dB.
These are set by the switches 10dB to 40dB. Only one
amplification DIP switch is allowed to be in the 'on'
position at a time.
If the 500FSD10 is to be terminated with the line
impedance, the DIP switches T-T and T-R need to be
switched to 'on'. This is usually the case at both ends
of the line. If the modem is to be connected in a party-
line manner in between, these DIP switches have to
be 'off'. T-T terminates the low frequency (LF) line
NF1, which is formed by terminals X3-1 and X3-2. T-
R terminates the receiver pair NF2 of the four-wire
configuration with terminals X3-3 and X3-4.
left – 'off'
C-1
for future use
C-2
switch on sender
with RTS
2-W
four-wire mode
off
CTS inactive
green
The CTS is
switched on when
the carrier is
being established.
A transmit delay
time of 20-30ms
has to be adjusted
in DTE settings.
off
No signal received
green
Signal received
from DTE
right – 'on'
for future use
carrier always
active (four-wire)
two-wire mode
left – 'off'
-20dB
normal sending
power
20%
both raising
factors active: 60
%
40%
of upper
frequency
amplitude, none
active: no raise
10db
only one factor
allowed to be
active, all off: 0
20db
dB
30db
40db
T-T
no termination
NF1 (> 6 kΩ)
T-R
no termination
NF2 (> 6 kΩ)
Safety
D A N G E R
Interrupt the power supply before mounting or
dismounting the device.
WARNING
An easy to access manual interrupter has to be
installed into the power feed of the modem to be
able to disconnect the modem from the power
supply in the case of an emergency.
WARNING
The DC power supply has to fulfil the following
requirements in order to supply appropriate fire
protection:
Limited power source according to IEC 60950-1
•
or PS2 classified according to IEC 62368-1
Short-circuit current < 8A
•
WARNING
No plug shall be freely accessible in normal
operation due to safety reasons.
right – 'on'
decrease sending
power by 20 dB
raise upper
frequency
amplitude by 20
%
raise upper
frequency
amplitude by 40
%
10 dB amplifi-
cation
20 dB amplifi-
cation
30 dB amplifi-
cation
40 dB amplifi-
cation
line termination
NF1
line termination
NF2
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