Figure 4.15 S2 Speed Shift Command Example - Honeywell PPT User Manual

Figure 4.14 shows the same pressure signal with a 1 second integration time reducing the noise varia-
tions on the output readings. Of course, the penalty for doing this is reducing the response time to rapidly
changing pressures that are not considered noise.
Pressure
(psi)
5.24
5.20
5.16
5.12
5.08
5.04
5.00
4.96
4.92
1.
0
Figures 4.15 and 4.16 illustrate rapid pressure changes using the S2 and S5 commands. The Speed Shift
commands (S2, S5) allow the tracking of rapid changes while sampling less often when pressures are
slowly changing. A threshold is set independently for the S2 and S5 commands that tell the PPT when to
begin outputting samples at the higher rate. The S2 command causes the output rate to double. The S5
command causes the readings to be output at 50 msec intervals synchronous with the normal reading
rates.
Pressure
(psi)
10.00
9.00
8.00
7.00 S2 Threshold
(±0.15 psi)
6.00
5.00
4.00
3.00
2.00
1.
0
Speed Shift S2=15 sets the threshold for x2 output rate
change as 15 x 0.01% FS = 0.15%FS. For a 100psi device,
this equals a ±0.15 psi pressure change.
Figure 4.15—S2 Speed Shift Command Example
Integration Time
Integration Time = 1 sec
(I=R1 sets 1 reading/sec)
2.
0
Figure 4.14—Integration (I=) Command, Example 2
Speed Shift - S2
x1
x2
3.0
2 1
(1 sec)
I =R1
S2 = 0
RR = 0 OP=A
Integration time
PPT pressure output
Actual pressure
Time (sec)
3.
0
I = M5
S2 = 15 S5 = 0
IC = 0
OP=A
x1 x2
.0
5
PPT pressure output
Actual pressure
IC = 0
S5 = 0
DO=S
RR = 0
Time (sec)