How to constrain asymptotes in 4PL fitting

[#1]

A little background info:
New user of JMP here, running JMP16 and know how to perform basic 4PL fitting and analysis with JMP.

Here is the question:
We often need to set values of upper or lower asymptote when fitting incomplete IC50 curves with 4PL analysis.
Is there a way to do this with JMP?

Thanks

[#2]

You will need to use a custom model. it will be the same model as in the Model Library of the Nonlinear platform or one of the 4PLC models in Fit Curve, but instead of 4 parameters, you will only use 3 of them. The 4th is the asymptote, and set this in the formula to the constant that you want to use.

Please see the JMP Help about using the Model Library. Create the 4PLC model as a column library, then edit the formula and change one of the two asymptote parameters to the desired constant.