Exercising proper wiring practice is
important in any control system. Ground loops and
electrical noise can impact both analog and HART data.
Analog+HART input modules have single-ended inputs. All
signal commons are tied together.
The module will support both
2-wire and 4-wire field devices. Some 4-wire field devices do
not provide isolation between the device power supply and
the 4-20mA loop. These devices may cause a ground loop
condition resulting in loss of HART communication or poor
quality analog data. Check with your device manufacturer
for isolation specifications.
If sufficient isolation is not
available you may use an external isolator on that device loop
to correct the problem. It is important that the isolator
be HART-compliant otherwise the HART signal will be lost.
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