Project file created by RSLogix, an application used for programming Allen-Bradley programmable logic controllers (PLCs); contains saved program logic built using the free-form ladder editor; used for storing PLC "ladder logic" designs. RSP files may also be backups of projects automatically generated by the software. For a project file named project.rsp, the software generates files project_BAK000.rsp, project_BAK001.rsp, project_BAK002.rsp, etc. RSP files are created by RSLogix 5, RSLogix 500, and RSLogix 5000
The RSP file extension was also used for scripts in old Rapport program from Wyse. Looks like no longer available software and probably obsolete file type without support from developer, or distributor.