Campbell Scientific AVW200-series Vibrating Wire Interfaces - Manual (Page 109)

Appendix I. Using MD485 Multidrop Modems with AVW200 Interfaces
'CR1000 Series Datalogger
'This program measures 2 sensors on 2 AVW200s PBA1 and PBA5.
'Each AVW200 is connected to a MD485 via a RS-232 null modem. The RS-232 baud rate of the MD485s
'is 38.4 k as is the RS-485 baud rate. The MD485s are set to Pakbus Network
'the Thermister reading is converted from Ohms to Deg C
Public PTemp, batt_volt
Public Dst(2,6)
Public TempC(2), TempK(2)
Public Rf(2)
Public result(2)
'ABC=temp coefficients for the Steinhart-Hart equation to convert Ohms to TempC
const A=.001403040
Const B=.000237318
const C=.00000009
DataTable (AVW200,1,-1)
DataInterval (0,10,Sec,10)
Sample (6,Dst(1,1),IEEE4)
Sample (6,Dst(2,1),IEEE4)
EndTable
DataTable (AVWcard,1,-1)
CardOut (0 ,-1)
DataInterval (0,10,Sec,10)
Sample (6,Dst(1,1),IEEE4)
Sample (6,Dst(2,1),IEEE4)
EndTable
BeginProg
SerialOpen (ComRS232,38400,0,0,10000)
Scan (10,Sec,0,0)
PanelTemp (PTemp,250)
Battery (Batt_volt)
'Result, comport,neighbor,PBA,Dst,chan,muxchan,reps,begFreq,endFreq,Vx,IntegrationTime,Mult,Offset)
'sensor 1, channel 1
AVW200(result(1),ComRS232,1,1,Dst(1,1),1,1,1,1000,3500,2,_60HZ,1,0)
'sensor 2, channel 2
AVW200(result(2),ComRS232,5,5,Dst(2,1),1,1,1,1000,3500,2,_60HZ,1,0)
Rf(1)=Dst(1,6)
Rf(2)=Dst(2,6)
TempK(1) = 1/(A + B*LN(Rf(1)) + C*(LN(Rf(1)))^3)
TempK(2) = 1/(A + B*LN(Rf(2)) + C*(LN(Rf(2)))^3)
TempC(1) = TempK(1)-273.15
TempC(2) = tempK(2)-273.15
CallTable avw200
CallTable avwcard
NextScan
EndProg
I-5