If process controller have analog input range 2 - 8Vdc to represent temperature range 0 – 100°C. So that we calculate range of resister, it is equal resistance 500 Ohm. Because if we use resistance 400 Ohm, in case current equal 4 mA, it occur only 1.6 V. When we use resistance 500 Ohm, the maximum analog input range will increase from 8Vdc to 10Vdc because the current signal generate maximum equal 20 mA and we add resistance to 500 Ohm. And then we have new range of temperature that is 0 – 133.33°C. The range of temperature can calculate by linear equation.