float code RTD_TAB_PT100[211] = // 表格是以5度为一步，即-200, -195, - 190.....
{
18.52,20.68,22.83,24.97,27.10,29.22,31.34,33.44,35.54,37.64, // -200 ~ -155 10
39.72,41.80,43.88,45.94,48.00,50.06,52.11,54.15,56.19,58.23, // -150 ~ -105
60.26,62.28,64.30,66.31,68.33,70.33,72.33,74.33,76.33,78.32, // -100 ~ -55
80.31,82.29,84.27,86.25,88.22,90.19,92.16,94.12,96.09,98.04, // -50 ~ -5
100.00,101.95,103.90,105.85,107.79,109.73,111.67,113.61,115.54,117.47, // 0 ~ 45
119.40,121.32,123.24,125.16,127.08,128.99,130.90,132.80,134.71,136.61, // 50 ~ 95
138.51,140.40,142.29,144.18,146.07,147.95,149.83,151.71,153.58,155.46, // 100 ~ 145
157.33,159.19,161.05,162.91,164.77,166.63,168.48,170.33,172.17,174.02, // 150 ~ 195
175.86,177.69,179.53,181.36,183.19,185.01,186.84,188.66,190.47,192.29, // 200 ~ 245
194.10,195.91,197.71,199.51,201.31,203.11,204.90,206.70,208.48,210.27, // 250 ~ 295
212.05,213.83,215.61,217.38,219.15,220.92,222.68,224.45,226.21,227.96, // 300 ~ 345
229.72,231.47,233.21,234.96,236.70,238.44,240.18,241.91,243.64,245.37, // 350 ~ 395
247.09,248.81,250.53,252.25,253.96,255.67,257.38,259.08,260.78,262.48, // 400 ~ 445
264.18,265.87,267.56,269.25,270.93,272.61,274.29,275.97,277.64,279.31, // 450 ~ 495
280.98,282.64,284.30,285.96,287.62,289.27,290.92,292.56,294.21,295.85, // 500 ~ 545
297.49,299.12,300.75,302.38,304.01,305.63,307.25,308.87,310.49,312.10, // 550 ~ 595
313.71,315.31,316.92,318.52,320.12,321.71,323.30,324.89,326.48,328.06, // 600 ~ 645
329.64,331.22,332.79,334.36,335.93,337.50,339.06,340.62,342.18,343.73, // 650 ~ 695
345.28,346.83,348.38,349.92,351.46,353.00,354.53,356.06,357.59,359.12, // 700 ~ 745
360.64,362.16,363.67,365.19,366.70,368.21,369.71,371.21,372.71,374.21, // 750 ~ 795
375.70,377.19,378.68,380.17,381.65,383.13,384.60,386.08,387.55,389.02, // 800 ~ 845
390.48 // 850
};
/***********************************************************************
*FunName: float CalculateTemperature(float fR)
*
*In: fR -> PT100的电阻值。
*
*Out: fTem -> 测得的温度值。
*
*Discription: 将电阻值查表算出温度值。
*
*Notes: 采用2分查找法。 ************************************************************************/
float CalculateTemperature(float fR)
{
float fTem;
float fLowRValue;
float fHighRValue;
int iTem;
uchar i;
uchar cLimite = 0xFF;
uchar cBottom, cTop;
if (fR < RTD_TAB_PT100[0]) // 电阻值小于表格最值低于量程下限。
{
return BELOW_LOW_LIMITE;
}
if (fR > RTD_TAB_PT100[210]) // 电阻值大于表格最大值，超出量程上限 。
{
return EXCESS_UP_LIMITE;
}
cBottom = 0;
cTop = 210;
for (i=105; (cTop-cBottom)!=1; ) // 2分法查表。
{
if (fR < RTD_TAB_PT100[i])
{
cTop = i;
i = (cTop + cBottom) / 2;
}
else if (fR > RTD_TAB_PT100[i])
{
cBottom = i;
i = (cTop + cBottom) / 2;
}
else
{
iTem = (uint)i * 5 - 200;
fTem = (float)iTem;
return fTem;
}
}
iTem = (uint)i * 5 - 200;
fLowRValue = RTD_TAB_PT100[cBottom];
fHighRValue = RTD_TAB_PT100[cTop];
fTem = ( ((fR - fLowRValue)*5) / (fHighRValue - fLowRValue) ) + iTem; // 表格是以5度为一步的。
// 两点内插进行运算。
return fTem;
}