Emerson Rosemount 5408 Reference Manual page 164

Specifications and Reference Data
Figure A-3:
Maximum Loop Resistance = 43.5 * (External Power Supply Voltage - 12)
A.
B.
Cable selection
Use 24-14 AWG wire. Twisted pairs and shielded wiring are recommended for
environments with high EMI (electromagnetic interference).
Two wires can be safely connected to each terminal screw.
Analog signal on alarm
The transmitter automatically and continuously performs self-diagnostic routines. If a
failure or a measurement error is detected, the analog signal will be driven offscale to alert
the user. High or low failure mode is user-configurable.
Table A-3:
Standard
Rosemount standard
NAMUR NE43
Analog saturation levels
The transmitter will drive the output to high or low saturation values if measurement goes
outside the 4-20 mA range values.
154
Load Limits
Loop Resistance (Ohms)
External Power Supply Voltage (Vdc)
Signal on Alarm
High
≥ 21.75 mA (default)
≥ 22.50 mA (option code C4)
Low
≤ 3.75 mA (option code C8)
≤ 3.6 mA (option code C5)
Reference Manual