Campbell CR800 Series - Measurement: Excite, Delay, Measure

Section 7. Installation
239
o SubScan()/NextSubScan introduces potential problems. These are
discussed in SubScan() / Next Sub
(p. 155).
o SubScan()/NextSubScan Counts cannot be larger than 65535.
o For SubScan()/NextSubScan to work, set Scan()/NextScan
Interval large enough for Counts to finish before the next
Scan()/NextScan Interval.
7.7.13 Measurement: Excite, Delay, Measure
This example demonstrates how to make voltage measurements that require
excitation of controllable length prior to measurement. Overcoming the delay
caused by a very long cable length on a sensor is a common application for this
technique.
Measurement with Excitation and Delay
'This program example demonstrates how to perform an excite/delay/measure operation.
'In this example, the system requires 1 s of excitation to stabilize before the sensors
'are measured. A single-ended measurement is made, and a separate differential measurement
'is made. To see this program in action, connect the following terminal pairs to simulate
'sensor connections:
' Vx1 ------ SE1
' Vx2 ------ DIFF 2 H
' DIFF 2 L ------ Ground Symbol
'
'With these connections made, variables VoltageSE and VoltageDiff will equal 2500 mV.
'Declare variables.
Public VoltageSE As Float
Public VoltageDIFF As Float
'Declare data table
DataTable (Voltage,True,-1)
Sample (1,VoltageSE,Float)
Sample (1,VoltageDIFF,Float)
EndTable
BeginProg
Scan(5,sec,0,0)
'Excite - delay 1 second - single-ended measurement:
ExciteV (Vx1,2500,0) '<<<<Note: Delay = 0
Delay (0,1000,mSec)
VoltSe (VoltageSE,1,mV5000,1,1,0,250,1.0,0)