W=
Width of Pressure Window
Set the width, or span, of the pressure window to a smaller range to fill the analog output voltage limits.
This command sets a pressure window value, or span, from 0 to 99% of full scale. An
W=
inquiry reads
the value in percent of full scale (
F=
value). This command is used with the
O=
,
L=
, and
H=
commands
to customize the size of the PPT analog pressure window and analog output voltage. If there is an input
error, then the command error flag in the
RS
command will be set and no change will occur. This com-
mand is enabled by the
AN
command. See Figure 4.5 for command illustration. (Default:
W=100
)
For example when L=0 and H=0, if a 20 psia, psig, or psid unit has the pressure window width set to
W=60
, then the 0 to 5 volt analog output span would correspond to 0 to 12 psi (60% of 20 psi). Use
the
O=
command (
O=20
) to offset the pressure window by 4 psi. Now the analog output values range
from 0 volt=4 psi up to 5 volt=16 psi.
If a 20 psid unit has the pressure window width set to
W=60
, then the pressure window would be 24
psi (60% of 40 psi). The analog 0V output would begin at -20 psi, cross 2.5V at -8 psi, and output 5V
at 4 psi. If a window offset of
O=20
was set, then the analog 0V output would begin at -12 psi, cross
2.5V at 0 psi, and output 5V at 12 psi. If an
O=
value is set > 40, then it is automatically set to 40.
Note
: Setting a pressure window (W=) value that causes the maximum output pressure to exceed 5V
will automatically scale to window offset (
O=
) value to maintain the 5V limit.
Inquiry: *dd
W=
Action: *dd
WE
*dd
W=
pp
|
S
EEPROM Store: *dd
WE
*dd
SP=ALL
pp
0 - 100
(%) This number is a percent multiplier (%) of the full scale pressure that sets the
pressure span across the analog output range. It can also be thought of as scaling, or
shrinking, the pressure window to fill the output voltage range. A
W=0
setting will set the
pressure window is 100%, full span. A
W=
entry greater than 100 will set
W=
100.
..............................................................................................................................
S
This enables the analog output setpoint. The setpoint trip voltage is controlled by the
O=
command. The setpoint null, or hysteresis, is controlled by the
DS
command. The setpoint
off voltage is controlled by the
L=
command and the on voltage is controlled by the
H=
command. See Figure 4.8 for command illustration.
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