1
-
3
UM344-2 INTRODUCTION
September 1995
FIGURE 1-2 Terminal Connections
1.2 PRODUCT DESCRIPTION
The Model 344 Temperature Transmitter, shown in Figure 1-1, is a microprocessor-based measurement
and control device which combines accurate, reliable temperature measurement and a PID controller in
one unit. The Transmitter accepts an RTD, thermocouple, millivolt, slide wire or resistance sensor input.
It contains a custom ASIC (Application Specific Integrated Circuit) which contains standard temperature
calibration curves for J, K, E, T, R, S, B and N type thermocouples and US/DIN curves for 100, 200, and
500 ohm Platinum RTDs. The sensed signal is linearized and corrected for ambient temperature changes
by the microprocessor and then converted to an equivalent 4-20 mA or HART® (Highway Addressable
Remote Transducer) digital output signal.
The analog output signal, HART digital communications, and 24 Vdc power (typical) are carried on a
twisted-pair 2-wire cable. The HART digital communication signals are superimposed (AC coupled) onto
the 4-20 mA loop current allowing simultaneous communication with the Transmitter without
compromising loop integrity. A digital meter is available when local indication of transmitter output is
required. Loop wiring connections made to the electrical terminals shown in Figure 1-2.
A transmitter can be configured to operate in either an analog mode or a digital mode, for a Point-To-Point
or a Multi-Drop network respectively.
ANALOG MODE: A single transmitter is connected to a controller, recorder or other field device. A loop
known as a Point-To-Point Network interconnects the instruments. The transmitter's output is the process
variable and it is sent to a controller or recorder using a standard 4-20 mA analog current.
TEST
+-
Ground
Screw
Signal (+)
Terminal
Signal (-)
Terminal
Test (+)
Terminal Test (-)
Terminal
Thermocouple, RTD,
Ohms,or mV Input
Notes:
1. Viewed with enclosure cap
removed.
2. MXC = Moore XTC
Communicator.
X02869S1
MXC
Connections
Sensor Terminals for
SIGNAL