The userBlockPA() function is called when you first enter a DLL file/function pair in the dialog for the userFunction block, or when a diagram is first read into Embed. This call is not required if block menu insertion is used.
long PASCAL userBlockPA(short *ppCount)
This function returns the parameter storage requirements, in bytes, for the userFunction block, and the number of prompted parameters. If you want Embed to prompt for parameter values, set ppCount to the desired number. The maximum value for ppCount is 12. You need to allocate eight bytes for each prompted parameter. You can request additional storage for a function’s private use. This additional storage can be accessed as array elements of the parameter vector after the first ppCount elements.
When this function is not supplied, no parameter storage is allocated.