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Reference Manual
00809-0100-4021, Rev DA
November 2004
A-7
Rosemount 3144P
Temperature Limits
HART Communicator Connections
375 Field Communicator connections are permanently fixed to power/signal
block.
Failure Mode
The 3144P features software and hardware failure mode detection. An
independent circuit is designed to provide backup alarm output if the
microprocessor hardware or software fails.
The alarm level is user-selectable using the failure mode switch. If failure
occurs, the position of the hardware switch determines the direction in which
the output is driven (HIGH or LOW). The switch feeds into the
digital-to-analog (D/A) converter, which drives the proper alarm output even if
the microprocessor fails. The values at which the transmitter drives its output
in failure mode depends on whether it is configured to standard,
or NAMUR-compliant (NAMUR recommendation NE 21, 1999) operation. The
values for standard and NAMUR-compliant operation are as follows:
Table A-2. Operation
Parameters
Load Limitations
NOTE
HART Communication requires a loop resistance between 250 and 1100
ohms. Do not communicate with the transmitter when power is below 12 V dc
at the transmitter terminals.
Description Operating Limit Storage Limit
Without LCD Display –40 to 185 °F
–40 to 85 °C
–60 to 250 °F
–50 to 120 °C
With LCD Meter –4 to 185 °F
–20 to 85 °C
–50 to 185 °F
–45 to 85 °C
Standard
(1)
(1) Measured in milliamperes
NAMUR-Compliant
(1)
Linear Output: 3.9 ≤ I ≤ 20.5 3.8 ≤ I ≤ 20.5
Fail HIGH: 21.75 ≤ I ≤ 23 (default) 21.5 ≤ I ≤ 23 (default)
Fail Low: I ≤ 3.75 I ≤ 3.6
Maximum Load = 40.8 X (Supply Voltage - 12.0)
(1)
(1) Without transient protection (optional).
1240
1000
750
250
0
10
12.0 Min
18.1 30 42.4
Supply Voltage (V dc)
HART and Analog
Operating Range
4–20 mA dc
Load (Ohms)
500
1100
Analog Only
Operating Range