Operation
PT12
Manual
7/20/2021
Page
10
of
48
OPERATION
The
PT12
measures
temperature
by
ratiometric
comparison
of
the
unknown
resistance
of
a
temperature
probe
to
a
series
of
temperature
stable
precision
reference
resistors.
Through
custom
selection
of
the
four
reference
resistors,
the
PT12
operating
range
and
precision
can
be
tuned
for
either
25
Ω
PRTs
or
100
Ω
PRTs.
Alternatively,
it
can
be
customized
to
cover
both
ranges
with
slightly
less
overall
precision.
(For
more
information
on
customization,
contact
RH
Systems).
The
PT12
supports
three
distinct
current
modes
which
can
be
manually
or
automatically
selected.
The
three
current
modes
available
are
approximately
0.3
mA,
0.6
mA,
and
1
mA.
The
PT12
will
attempt
to
get
the
most
accurate
reading
possible
when
utilizing
auto
current
mode.
4.1
CONNECTING
TEMPERATURE
PROBES
There
are
12
LEMO
connectors
(one
per
probe)
on
the
PT12
and
any
number
of
probes
(between
1
and
12)
may
be
connected
in
any
order
at
any
given
time.
To
connect
a
probe,
ensure
the
red
dots
between
the
plug
and
receptacle
are
aligned,
then
push
to
connect.
Pulling
up
on
the
body
of
the
plug
releases
the
catch,
allowing
the
probe
to
be
removed.
Once
inserted,
the
PT12
will
automatically
detect
the
probe
and
determine
if
it
is
a
smart
probe
(with
internal
configuration
memory)
or
a
basic
probe
(without
any
memory).
