Black Box IC108A Guía de usuario descargar pdf (Pagina 110)

Advant

Smart Device (HART

) Interface User’s Guide

Chapter 5 Maintenance

5-6 3BUR 001 085R0001 REV A

NOTE

The physical connection between a smart device and a SHIM is made using a

cable referred to as a HART Bus. The HART Bus cable is a 18 to 20 AWG,

shielded twisted pair.

The maximum length of the HART Bus is 10,000 ft. (3,048 m) or is determined

using the following formula, whichever is less:

L = 65,000,000 / (R x C) - (C

+ 10,000) / C

where L is the length in feet or meters, R is the total loop resistance in ohms, C is

the cable capacitance in pF/ft. or pF/m, and C

is the sum of CN values of smart

devices multiplied by 5,000 pF. For smart devices without CN values, use 1.

Masters (primary and secondary) need not be counted in deriving C

Smart Device Installation

To install a smart device:

1. Dress the wires at both ends of the HART Bus cable for easy connection to the smart

device and SHIM screw terminations.

2. Screw the wires at one end of the HART Bus cable to the screw terminations for the

positive and negative contacts of the smart device.

3. For the communication of both analog and digital signals from a smart device, the

connections you make with the wires at the other end of the HART Bus depend on the type

of I/O used to bring the signals into the Advant Controller.

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Black Box IC108A Guía de usuario Pagina 110