Martel Electronics LC-110/H - Manual (Page 19)

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6. HART Device Communications
The HART functions are only available in the LC-110H.
Auto shutdown is disabled on entry to the HART Menus and is
restored to its previous state upon exit from the HART menus.
Loop current trim is supported for transmitter devices, but is not
supported for actuator devices.
All functions on the Modify Setup menu, and the device diagnostic,
trim 4 mA, trim 20 mA, fixed output, and PV zero functions may be
disabled using the ‘HART Write Enable’ selection on the Calibrator
Setup Menu, described in section 4.8. If any of these functions are
required, they must be enabled before entering the HART menus.
6.1. HART Connection Diagrams
6.1.1 In Circuit, External Loop Power
In “mA Measure” mode the LC-110H is in circuit and loop power is
supplied externally as shown below.
24V
SUPPLY
(+)
(–)
4 to 20mA
MARTEL ELECTRONICS
LC-110H Precision Loop
Calibrator w/HART™
100%
25%
0%
MENU
EXIT
Measure 0.00%
4.000mA
250 Ω
Note: In this situation the 250 Ω HART resistor is enabled. If your loop
already has 250 Ω, do not enable the HART resistor.