Emerson Rosemount 644h, Reference Manual

Page: 20 / 78

Reference Manual
00809-0100-4728, Rev HA
December 2002
Models 644H and 644R
2-10
Figure 2-6. Transmitter Power,
Communication, and Sensor
Terminals
Figure 2-7. Connecting a
Communicator to a Transmitter
Loop
Sensor Connections
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.
Figure 2-8. Sensor Wiring
Diagrams
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.
Model 644H Model 644R
1 2 3 4
Sensor
Terminals
Communication
Terminals
Power Terminals
Sensor
Terminals
Power/
Configuration
Terminals
Max torque is 6
in.-lbs (0/7 N-m)
Model 644H Model 644R
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)
250
≤
R
L
≤
1100
Power
Supply
HART
Communicator
250 ≤ R
L
≤ 1100
64
4-
0
0
0
0
A0
2A,
000
0A
02B
Power
Supply
HART Communicator
Model 644 Sensor Connections Diagram
* 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.
2-wire
RTD and
3-wire RTD
and
4-wire RTD
and
T/C
and mV
*
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
64
4-00
0B01
A