Spectrum Controls 1769sc-HART Modules - Manual (Page 12)

Compact™ IO Isolated HART Analog Input Module
User's Manual 0300215-03 Rev. A
1-4
Section 1.6
Module
Operation
When the module receives the input from an analog device, the module’s circuitry
multiplexes the input into an A/D converter. The converter reads the signal and converts
it as required for the type of input. If HART is enabled on a channel, the HART data is
acquired my means of an onboard HART modem.
Note: The HART data is acquired asynchronously from the analog acquisition process
and therefore does not directly effect the analog update time.
See the block diagram below.
Figure 1-2
The module is designed to support up to 4 isolated channels which can be independently
configured for voltage, current, or current with HART. The module converts the analog
values directly into digital counts which are viewed and accessed from within the PLC
via controller input tags.
The HART data, if enabled, is converted directly to a block of twenty controller input
tags. The data within this block of twenty tags is multiplexed. For information on HART
and how to demultiplex the HART data, refer to Chapter 7.