The DRA-RTM-8 is a 16 channel
analog multiplexer. Eight channels
accept 3-wire 100 Ohm Pt RTD
inputs, and the other eight channels
accept 4-20 mA process inputs. All
16 inputs are multiplexed into a
single 4-20 mA current loop output.
The selection function is performed
via four binary control lines
generated by the host controller
(PLC program).
Model DRA-RTM-8 is an all solid
state unit that multiplexes the input
channels at a switching time of less
than 20 microseconds. Each of the
RTD inputs is completely signal
conditioned including a 6 dip-switch
array for coarse channel ranging as
well as zero and span trimmers on
the front panel for fine ranging.
Special attention is given to the lead
length compensation parameter
because, unlike ordinary
transmitters, the DRA-RTM-8 could
be mounted relatively far from the
RTD sensors. The 4-20 mA output from the DRA-RTM-8 is linearized to
the RTD input.
The DRA-RTM-8’s superb accuracy
and simple operation make it a very
attractive unit allowing tremendous
cost savings by reducing the need
for expensive PLC or data
acquisition analog inputs.
