Files in the PLY file format come in two variants: ASCII and binary. Some programs have problems dealing with a binary PLY file and can only deal with a ASCII PLY file. There are many programs available to convert between ASCII and binary PLY files. I had some problems with the converted files when I used programs like
ply2ascii to do this conversion.
Instead, I discovered that MeshLab is not only a cool mesh viewer program, but can also convert between many mesh formats. It supports conversion between PLY too:
Open the original (say binary) PLY file by using File → Import Mesh.
Export this file to the (say ASCII) PLY file format by using File → Export Mesh As. Choose PLY file format in the Save dialog.
MeshLab shows a dialog specific to PLY. Here depending on which (ASCII or binary) PLY format you want, choose the Binary encoding radio button. Your PLY file is converted! 😊
Tried with: MeshLab 1.3.0