Dear all i have a problem with a pt100
when the temperature exceeds 15 ° C, I get a NAN..
i don't understand why.
Maybe the sensor is defective?
please find a part of my code bellow.
Public pt100_1
Units pt100_1=Deg C
'Define Data Tables
DataTable(Table1,True,-1)
DataInterval(0,10,Min,10)
Average(1,pt100_1,FP2,False)
EndTable
'Main Program
BeginProg
PortSet (9,1)
'Main Scan
Scan(3,Sec,1,0)
If TimeIntoInterval (1020,1440,Min) Then PortSet (9,0) 'turn SW12 off
If TimeIntoInterval (420,1440,Min) Then PortSet (9,1) 'turn SW12 on
'PT100 PRT Temperature Probe (3WHB10K) (CSL) measurement 'pt100_1'
BrHalf3W(pt100_1,1,mV20,15,2,1,4200,True,0,_50Hz,101.6,0)
PRT(pt100_1,1,pt100_1,1,0)
can you tell me if it's correct?
i'm lost
regards
If you are using a 10k bridge resistor and this is a CR3000, your problem is the range code is too low. It should be mV50 not mV20.
Dear APS
many thanks for your answer so thats work better when i put the range code on mV50 but, when the temperature exceeds 85°C i have the same problem : a NAN
have you an idea of the problem?
regards
You can avoid this by reducing the excitation voltage a little. See the datalogger manual for a discussion of this (7.8.18.2.2 PT100 in Four-Wire Half-Bridge). The exact voltage you set is a balance between the maximum temperature you can measure and the resolution of the measurements.