Campbell Scientific AVW200 AVW200-series Vibrating Wire Interfaces - Page 109
Appendix I., Using MD485 Multidrop Modems with AVW200 Interfaces, AVW200s PBA1 and PBA5.
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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