Hello, I am attempting to build a model that adds a new field to an attribute table, lets call it New_Temperature, and then calculates a value for that field by adding a value, determined by the user, to the original Temperature field. For example, I would like to create a new field that is 7 degrees more that the original field. I have included a screen shot of the model that I attempted to build. Plots is the .shp file with the attribute table. I got the first step to work, where the model adds a new field, but I get a warning saying that "The process did not execute because the precondition is false."
I am pretty new to this, so I'm not sure I specified everything correctly. In the Calculate Temperature box I put "[Tma_ºC_] + %Temperature Change%" for the expression field, so I assume that means the Calculate Field box will take the value that is input in to the Temperature Change box and add it to the original Temperature field, denoted as "[Tma_ºC_]". Is that correct?
Also, I connected the New Temp Field variable to the Calculate Field box with an Input Table connector, so I guess that the Calculate Field box is using New Temp Field as the input table, which would not work because it is an empty field. I did, however, try to run the model with the Calculate Field box connected directly to the Plots variable, but got the same error.
Thanks, any help is greatly appreciated...
Graham