Embedding a standard equation in a custom equation

In this example we will have a pressure transducer that measures 0 - 100psi and outputs a proportional, linear signal from 4-20 mA. The transducer would be connected to one tf the 0-25mA chanells on a SRP007 logger. The standard equation for the 25mA channel is "eqn(6)". We simply add 300 to the existing equation number to yield "eqn(306)" for an SRP logger, or just "eqn(6)" for an SR logger. We then substitute this expression for the letter "N" in the above equation. Work throught the rest of the formula:

Answer0 = eqn(306) * 1000 * { (100 - 0) / (20 - 4) } - { 20 * (100 - 0) / (20 - 4) } - 100 }

The final equation will look like this:

Answer0 = eqn(306) * 6250-25

This is the equation that you will enter in the main text box of "New Equation" in TrendReader for Windows when you actually create the equation and save it in your computer. See "Writing Custom Equations" in the TrendReader Reference manual. (Note: The 1000 in the above example is a conversion factor necessary to make TrendReader display the correct results. Equation #6 works in milliamperes but the program bases its calculations on Amperes.)

NOTE: It should be noted that when creating custom equuations for the SmartReader Plus 10, even equation numbers are to be used with 100 ohm RTD probes and odd equation number in the TrendReader software to accomodate this.