Simulink: Why is it so hard to have copies of a block?

I have a library of different components for heat transfer analysis. Two of them are basically copies of each other (the evaporator and condenser) with tiny differences. They use an S Function that is written in matlab.

Now, whenever I have them both in a simulink model at the same time, I get an error that has something to do with simulink being unable to differentiate between the Pressure variable of the two blocks.

I found out that this error is resolved when I use a CMEX function instead of the matlab sFunction. Anyone know why this might be happening?

Also, since I had the CMEX function from a former colleague, I do not know how to convert my matlab sFunction into a C SFunction. I tried using the Matlab Coder, but I got the same error as this guy: http://www.mathworks.com/matlabcentral/answers/53964

I tried using an Fcn block instead (with one input (u) and one output (sys), hoping to replicate sFunction functionality , but simulink threw an error about wrong dimensions.

Any advice? Thanks in advance for any help.

[Ketan]

Any chance you can provide the Simulink error messages when

1) The two MATLAB S-functions are used within a model

2) Trying to port over the MATLAB s-function to MATLAB function block

[Viren]

Hi Ketan

Thanks for taking the time to reply. I would provide the error message, but I fear it won't be much use. We use a proprietary 'library' of functions that is used to calculate refrigerant properties. The error comes from that library, although it's origin is likely in Simulink rather than the library itself.