Sensor Connections - Emerson Rosemount 644H Reference Manual

Models 644H and 644R
Figure 2-6. Transmitter Power,
Communication, and Sensor
Terminals
Figure 2-7. Connecting a
Communicator to a Transmitter
Loop

Sensor Connections

Figure 2-8. Sensor Wiring
Diagrams
2-10
Model 644H
Sensor
Terminals
Communication
Terminals
Power Terminals
Model 644H
250
HART
Communicator
Note: Signal loop may be grounded at any point or left ungrounded.
Note: A Model 275 HART Communicator may be connected at any termination point in the signal loop.
The signal loop must have between 250 and 1100 ohms load for communications.
Note: Max torque is 6 in.-lbs (0/7 N-m)
The Model 644 is compatible with a number of RTD and thermocouple sensor
types. Figure 2-8 shows the correct input connections to the sensor terminals
on the transmitter. To ensure a proper sensor connection, anchor the sensor
lead wires into the appropriate compression terminals and tighten the screws.
Model 644 Sensor Connections Diagram
1 2 3 4
2-wire
RTD and
* Emerson Process Management provides 4-wire sensors for all single element RTDs. Use these
RTDs in 3-wire configurations by leaving the unneeded leads disconnected and insulated with electrical
tape.
Thermocouple or Millivolt Inputs
The thermocouple can be connected directly to the transmitter. Use
appropriate thermocouple extension wire if mounting the transmitter remotely
from the sensor. Make millivolt inputs connections with copper wire. Use
shielding for long runs of wire.
1 2 3 4
≤ R ≤ 1100
L
Power
Supply
HART Communicator
1 2 3 4 1 2 3 4
* 4-wire RTD
3-wire RTD
and
and
Reference Manual
00809-0100-4728, Rev HA
December 2002
Model 644R
Sensor
Terminals
Max torque is 6
in.-lbs (0/7 N-m)
Power/
Configuration
Terminals
Model 644R
250 ≤ R ≤ 1100
L
Power
Supply
1 2 3 4
T/C
and mV