Siemens 353, Руководство пользователя, Страница: 52 / 246

Function Blocks UM353-1B
April 2012 3-22
3.2.13 AOUT_ - Analog Outputs
AOUT_ function blocks convert function block
interconnection signals, connected to input S, to
a block output having a range of 4-20 mAdc.
Input D can be used to disconnect the output
from the load when asserted high (1). This
feature is useful when two or more controllers
are connected to a common load. When one
controller is connected to the load, others are
disconnected using the disconnect feature. The
function block includes scaling to range the 4-
20 mA output with the block input signal. The
range pointer parameter (input R) tells the block
where to obtain scaling information. If this
parameter is not configured the block will use a
range of 0.00 to 100.00.
Two analog output function blocks are available
on the Controller Board and one additional on
the Expander Board. Function block names and
terminal identifications are listed below. The output is factory calibrated for 4-20 mAdc and should not require
field calibration. However, field calibration can be performed if desired. The output is calibrated by adjusting the
pulser until the desired output (i.e. 4.0 mA for zero) is obtained and then pressing the store button. A verify mode
(CAL VIEW) is available during calibration that will show the 0-100% signal driving the output circuit in the
numeric display as the pulser adjusts the output over the full range.
Output QS is the Quality Status output. It will go high if the output driver detects a high impedance or an open
circuit. The alphanumeric will flash AOUT_.OC when an open circuit condition is detected. The QS output could
also be used to switch to a second output circuit in a redundancy application.
BLOCK DIAGRAM
AOUT_+
Scaling D/A
S
AOUT_c
O utput
R
an
G
e
P
oin
T
e
R
AOUT_+
AOUT_c
ANALOG OUTPUT _
G R
T
C
C
Z E R O
F L L
V E I W
R an G e P oin T e R
(S)
.......
loop tag.block tag (null)
INPUT S
(H)
........
loop tag.block tag.output (null)
ZERO
output
(C)
....................... 4.0 mA
FULL scale output
(C)
.............. 20.0 mA
VIEW
output - verify cal.
(C)
................ %
ANALOG OUTPUT
U
AOUT_
R
T
C A L
L A
A L
I N P U S
I N P U T D
INPUT D
(H)
........
loop tag.block tag.output (null)
4 - 20 mA dc
P
D
S
D isconnect
S ignal
QS
Q uality S tatus
R R ange
Rev 3