3.2.2 CURRENT INPUTS
There are two types of current measurement possible, the first type measures the
current of an external loop, that is, a current that has been generated from an external
power supply, or from another instrument. The second type measures current
generated from the units own 20V excitation supply. Before connecting up a current
input it is important to establish which one of these two groups apply.
3.2.2.1 CURRENT MEASUREMENT OF AN
EXTERNALLY GENERATED LOOP
In order to measure the current in an
externally
generated
loop,
it
is
necessary to insert a resistor
in-circuit and use the instrument to
measure the resultant voltage drop.
Note that the instrument will need to
be configured as a 1-5V input and not
a 4-20mA input; this is described later
in the programming
section.
The
diagram shows the necessary
connections.
3.2.2.2 CURRENT MEASUREMENT OF AN
INTERNALLY GENERATED LOOP
The
instrument
has
an excitation
supply
which
can
be
used
for
generating a current loop. If this is
used, the circuit is connected in the
following way. Note that the current
input has an internal impedance of 50
ohms.
INSTALLATION
SENSOR CONNECTIONS
Page 14
Summary of Contents for DM4000U
Page 3: ...GETTING STARTED Page 3 ...
Page 7: ...INSTALLATION Page 7 ...
Page 25: ...USER GUIDE Page 25 ...
