Campbell Scientific CR3000 Micrologger - Manual (Page 258)

Section 7. Installation
258
'Declare Event Driven Data Table
DataTable (Event,True,1000)
DataEvent (0,DeltaT_C>=3,DeltaT_C<3,0)
Sample (1,PTemp_C, FP2)
Sample (1,AirTemp_C, FP2)
Sample (1,DeltaT_C, FP2)
EndTable
'Declare Time Driven Data Table
DataTable (OneMin,True,-1)
DataInterval (0,1,Min,10)
Sample (1,EventCounter, FP2)
EndTable
BeginProg
Scan (1,Sec,1,0)
'Wiring Panel Temperature
PanelTemp (PTemp_C,_60Hz)
'Type T Thermocouple measurements:
TCDiff (AirTemp_C,1,mV20C,1,TypeT,PTemp_C,True,0,_60Hz,1,0)
'Calculate the difference between air and panel temps
DeltaT_C = AirTemp_C - PTemp_C
'Update Event Counter (uses special syntax Event.EventCount(1,1))
EventCounter = Event.EventCount(1,1)
'Call data table(s)
CallTable (Event)
CallTable (OneMin)
NextScan
EndProg
7.8.18 PRT Measurement
PRTs (platinum resistance thermometers) are high-accuracy resistive devices used
in measuring temperature.
7.8.18.1 PRT Calculation Standards
Two CR3000 instructions are provided to facilitate PRT measurement.
PRT(): an obsolete instruction. It calculates temperature from RTD
resistance using DIN standard 43760. It is superseded in probably all
cases by PRTCalc().
PRTCalc(): calculates temperature from RTD resistance according to one
of several supported standards. PRTCalc() supersedes PRT() in probably
all cases.
For industrial grade RTDs, the relationship between temperature and resistance is
characterized by the Callendar-Van Dusen (CVD) equation. Coefficients for
different sensor types are given in published standards or by the manufacturers for