Using UDF Macro DEFINE_RW_FILE with Serial Version of Ansys Fluent

How can I use the Ansys Fluent UDF Macro DEFINE_RW_FILE with the serial version of Ansys Fluent?

Starting with Ansys Fluent 18.2 you must parallelize your UDF (user-defined function) also when using the serial version. Most macros are updated that they can be used with one or multiple compute nodes without special considerations but for DEFINE_RW_FILE you must be careful to do a proper parallelization.
See also the Ansys Fluent Migration Manual and Ansys Fluent Customization Manual, chapter “Parallelizing Your Serial UDF”.