March 2016
24
Quick Start Guide
6.5 Analog output
Field mount transmitter
The analog output signal is a 4–20mA current loop. The loop can be powered
internally or externally via a hardware switch located on the front of the
electronics stack. The switch is set to internal power when shipped from the
factory. For field mount units with a display, the LOI must be removed to change
switch position.
For HART communication a minimum resistance of 250 ohms is required. It is
recommended to use individually shielded twisted pair cable. The minimum
conductor size is 0.51mm diameter (#24 AWG) for cable runs less than 5,000-feet
(1,500m) and 0.81mm diameter (#20 AWG) for longer distances.
Internal power
The 4-20mA analog signal is a 24VDC active output.
Maximum allowable loop resistance is 500 ohms.
Wire terminal 1 (+) and terminal 2 (-). See Figure 25.
Figure 25. Field Mount Transmitter Analog Wiring - Internal Power
External power
The 4–20mA analog signal is passive and must be powered from an external
power source. Power at the transmitter terminals must be 10.8–30VDC.
Wire terminal 1 (-) and terminal 2 (+). See Figure 26.
NOTICE
Terminal polarity for the analog output is reversed between internally and externally powered.
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