Figure 4.16 S5 Speed Shift Command Example - Honeywell PPT User Manual

Pressure
(psi)
10.00
9.00
8.00
7.00
S5 Threshold
(±0.20 psi)
6.00
5.00
4.00
3.00
2.00
1.
0
Speed Shift (S5=20) sets the threshold for 50 msec output
rate change as 20 x 0.01% FS = 0.20%FS. For a 100psi
device, this equals a ±0.20 psi pressure change.
Figure 4.17 shows the effect of the deadband setting in the DS command. If a deadband of ±0.02%
FS is selected, then the pressure output will not change reading as long as it is within this limit
(±0.02psi for a 100 psi unit). If the pressure exceeds or falls below this threshold, the pressure
reading will track the actual pressure value. It will continue to track the pressure value until there is
no change again within the threshold limit.
Figure 4.18 illustrates the effect of the Idle Count (IC) command for four different pressure curves.
The IC command does nothing more than skip over a set number of readings. If the idle count were
set to IC=4, then after a pressure output reading, the PPT would not output the next 4 readings and
the fifth one would become the next output reading. This feature allows the reading rate to be estab-
lished different from the integration time. This feature is useful for minimizing the communications
traffic on a network of many PPT units.
Figure 4.19 illustrates the Synchronize Integration cycle (SI) command as well as the Transceiver
Operating parameters (TO) options that affect it. This is for RS-485 units only.
Pressure
(psi)
10.00
9.00
8.00
Deadband
7.00
(±0.4 psi)
6.00
5.00
4.00
3.00
2.00
1.
0
Figure 4.17a—Deadband and Sensitivity (DS) Command Examples
Speed Shift - S5
50 msec
readings
3.0 5
Figure 4.16—S5 Speed Shift Command Example
Deadband - Center
PPT pressure output
Actual pressure
3.0
2 2
50 msec
readings
.0
PPT pressure output
Actual pressure
I = M5
S2 = 0
IC = 0
Setting DS=40 sets the deadband to
±40 x 0.005% FS = ±0.20%FS.
Then setting DS=C1 selects the center
deadband option with a 10x multiplier.
For a 20 psi full scale device, this
results in a ±0.40 psi deadband window.
Time (sec)
5 .0
I = M5 DO=S
S2 = 0 S5 = 20
IC = 0 RR = 0
OP=A
Time (sec)
DS=40C1
S5 = 0
RR = 0 OP=A