Acromag TT231-0600, User Manual, Page: 8 / 41

Model TT231-0600 Two-Wire RTD Transmitter w/USB
Acromag, Inc. Tel: 248-295-0880
- 8 - http://www.acromag.com
- 8 - http://www.acromag.com
Output/Power Connections
This transmitter has an ANSI/ISA Type 2 output in which the unit’s power and
output signal share the same two leads, and the transmitter output has a floating
connection with respect to earth ground. Connect a DC power supply and load in
series in the two-wire loop as shown in drawing below.

Output connections are not polarized. The and – designations are for
reference only with current normally input to and returned via Output-
(current sinking).

Loop supply voltage should be from 9-32V DC with the minimum voltage level
adjusted to supply over-range current to the load, plus 9V minimum across the
transmitter, plus any transmission line drop.

Variations in power supply voltage between the minimum required and 32V
maximum, has negligible effect on transmitter accuracy.

Variations in load resistance has negligible effect on output accuracy, as long as
the loop supply voltage is set accordingly.

Note the traditional placement of earth ground in the current loop. The
transmitter output floats off this ground by the voltage drop in the load
resistance and lead-wire. This is very important when making USB Connections
and will drive the need for USB isolation (see USB Connections section).

Always connect the output/power wires and apply loop power before
connecting the unit to USB.
The traditional loop-powered “sinking” output connections are shown above.
Shielded twisted-pair wiring is often used at the output to connect the longest
distance between the field transmitter and the remote receiver as shown. The
output of this transmitter fluctuates relative to earth ground by the voltage drop in
the load and connection wire. This makes it flexible in the way it connects to
various “Receiver” devices.
INPUT SIDE OUTPUT SIDE
MODEL TT231-0600
MODEL TT231-0600 OUTPUT/POWER WIRING
+ -
C C
TB3
TB4
TOP VIEW
(OUTPUT SIDE)
6 5
8 7
TRADITIONAL LOOP-POWERED "SINKING OUTPUT" CONNECTIONS
+
-
+
I
DC SUPPLY
(9-32V)
+
-
EARTH
GROUND
I
I
R
LOAD
-
THIS TRANSMITTER IS CURRENT LOOP POWERED
4-20mA
NOTE: OUTPUT TERMINALS ARE NOT POLARIZED AND
PLUS & MINUS LABELS ARE FOR REFERENCE ONLY.
OPTIONAL WIRING TERMINALS C ARE HELD IN
COMMON AND USED FOR "SOURCING" LOOP WIRING.
SEE OPTIONAL OUTPUT WIRING DIAGRAM.
+
-
6
5
TWISTED PAIR
SHIELDED
OUTPUT
TERMINALS
(UPPER LEVEL)
OPT "C" TERMINALS
(SEE OPT TB4 WIRING)
ARE COMMON
7 8
TB3