User Manual
6
TAI16AI
R
October
200
5
–
Issue 5
Triguard
SC300E
EXTERNAL
CONNECTIONS
Fixed
Terminal
Details
Chassis
connector
J1
Connector,
34
-
way,
DIN41612,
female
Field
terminals
1 to
16(+)
and
1 to
16(
-)
Screw
terminals
to
suite
2.5mm
2
wire
(16AWG)
Field
power
supply
inputs
FS1
and
FS2
Header,
2
-
way,
Molex
Minifit
Jr
Alarm
output
PL1
Head
er,
2
-
way,
Molex
KK
Ground
terminal
TS1
Provision
for
M3
ring
terminal
THEORY OF OPERATION
The
termination
card
circuit
comprises
16
channels
each
fused
at
1A
with
a fast
acting,
indicating
fuse.
Figure
2
-
3 shows
the
connections
for
Channel
1,
all
other
channels
are
identical.
The
current
loop
field
device
is
connected
across
the
screw
terminals
1(+)
and
1(
-
) and
supplied
with
a nominal
24V
via
the
indicating
fuse
F1.
The
0
-
20mA
loop
current
from
the
field
device
re
-
enters
the
termination
card
and
develops
a voltage
across
the
250
ohm
precision
resistor
R1.
This
metered
voltage
is
applied,
via
J1/2a
and
J1/2c,
to
one
of
the
channels
of
a 0
-
5V
Analogue
Input
Module.
Use
of
the
precision
resistor
allows
the
output
voltage
to
be
applied
to
more
than
one
An
alogue
Input
Module
without
sharing
the
loop
current
so
that
two
modules
can
be
connected
in
parallel
for
‘hot
repair’
redundancy.
D1
is
a transient
suppressor
to
protect
the
module
input
against
the
effects
of
lightning
strikes,
etc.
on
the
field
equipmen
t.
Any
blown
fuse
lights
the
Fuse
blown
LED
LD1
and
also
provides
a remote
Alarm
output
via
PL1/1
and
2.
Power
for
the
circuit
and
for
the
field
devices
is
from
two
independent
supplies,
nominally
24V,
at
FS1
and
FS2.
The
positive
supply
lines
are
auctioned
via
D17
and
D18
to
ensure
even
power
consumption.
The
common
0V
line
is
connected
to
the
negative
side
of
all
the
module
input
channels.
The
common
0V
line
is
also
connected,
via
C1
and
R20,
to
the
M3
ring
terminal
TS1
which
should
be
connected
to
a s
uitable
earth
to
prevent
the
channels
floating
if
the
multicore
cable
to
the
chassis
is
disconnected.