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

Compact™ IO Isolated HART Analog Output Module
User’s Manual 0300217-03 Rev. A
1-4
Section 1.5
Module
Operation
When the module receives a new command value from the output image, the module’s
circuitry converts the digital value to an analog current signal using a DAC (Digital to
Analog Converter). The resulting signal is made available for the specific channel via the
removable terminal block. If HART is enabled on a channel, the HART data is acquired
my means of an onboard HART modem.
Note: The HART data is sent and received asynchronously from the analog
acquisition process and therefore does not directly affect 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 current, or current with HART.
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.
24 V TO 12V
POWER
SUPPLY
CPU
64 K Flash/
2 K RAM
16 BIT
DA
C
-
+
+15
V
OPTOS
VOUT
IOUT
GND
ISOLATED +/-15V
SUPPLY
OUTPUT CIRCUIT x4
16 BIT
DA
C
-
+
+15
V
OPTOS
VOUT
IOUT
GND
ISOLATED +/-15V
SUPPLY
16 BIT
DA
C
-
+
+15
V
OPTOS
VOUT
IOUT
GND
ISOLATED +/-15V
SUPPLY
16 BIT
DAC
+15
V
OPTOS
IOUT
GND
ISOLATED +-15V
SUPPLY
RET
MERCURY
ASIC
BA
C
K
P
L
ANE
C
O
NNECT
O
R
TER
M
IN
AL
BL
OC
K
500 VDC ISOLATION
HART
MODEM