Campbell CR850 - Page 284

Section 8. Operation
284


steady-state conditions so changes in measured voltage are attributable to settling
time rather than changes in pressure. Reviewing the section Programming
(p. 108)
may help in understanding the CRBasic code in the example.
The first six measurements are shown in table First Six Values of Settling-Time
Data
(p. 285). Each trace in figure Settling Time for Pressure Transducer (p. 285)
contains all twenty PT() mV/Volt values (left axis) for a given record number,
along with an average value showing the measurements as percent of final reading
(right axis). The reading has settled to 99.5% of the final value by the fourteenth
measurement, which is contained in variable PT(14). This is suitable accuracy for
the application, so a settling time of 1400 µs is determined to be adequate.
CRBasicExample63. MeasuringSettlingTime
'Program to measure the settling time of a sensor measured with a differential
'voltage measurement
Public PT(20) 'Variable to hold the measurements
DataTable(Settle,True,100)
Sample(20,PT(),IEEE4)
EndTable
BeginProg
Scan(1,Sec,3,0)
BrFull(PT(1),1,mV7_5,1,Vx1,1,2500,True,True,100,250,1.0,0)
BrFull(PT(2),1,mV7_5,1,Vx1,1,2500,True,True,200,250,1.0,0)
BrFull(PT(3),1,mV7_5,1,Vx1,1,2500,True,True,300,250,1.0,0)
BrFull(PT(4),1,mV7_5,1,Vx1,1,2500,True,True,400,250,1.0,0)
BrFull(PT(5),1,mV7_5,1,Vx1,1,2500,True,True,500,250,1.0,0)
BrFull(PT(6),1,mV7_5,1,Vx1,1,2500,True,True,600,250,1.0,0)
BrFull(PT(7),1,mV7_5,1,Vx1,1,2500,True,True,700,250,1.0,0)
BrFull(PT(8),1,mV7_5,1,Vx1,1,2500,True,True,800,250,1.0,0)
BrFull(PT(9),1,mV7_5,1,Vx1,1,2500,True,True,900,250,1.0,0)
BrFull(PT(10),1,mV7_5,1,Vx1,1,2500,True,True,1000,250,1.0,0)
BrFull(PT(11),1,mV7_5,1,Vx1,1,2500,True,True,1100,250,1.0,0)
BrFull(PT(12),1,mV7_5,1,Vx1,1,2500,True,True,1200,250,1.0,0)
BrFull(PT(13),1,mV7_5,1,Vx1,1,2500,True,True,1300,250,1.0,0)
BrFull(PT(14),1,mV7_5,1,Vx1,1,2500,True,True,1400,250,1.0,0)
BrFull(PT(15),1,mV7_5,1,Vx1,1,2500,True,True,1500,250,1.0,0)
BrFull(PT(16),1,mV7_5,1,Vx1,1,2500,True,True,1600,250,1.0,0)
BrFull(PT(17),1,mV7_5,1,Vx1,1,2500,True,True,1700,250,1.0,0)
BrFull(PT(18),1,mV7_5,1,Vx1,1,2500,True,True,1800,250,1.0,0)
BrFull(PT(19),1,mV7_5,1,Vx1,1,2500,True,True,1900,250,1.0,0)
BrFull(PT(20),1,mV7_5,1,Vx1,1,2500,True,True,2000,250,1.0,0)
CallTable Settle
NextScan
EndProg
