A REN (Remote Event Notification) server is used in PeopleSoft primarily for nVision on the web transactions. It also may be used for the optimization engine and that other new crap that PeopleSoft is now pushing. I don't really know a whole lot about.
PSRENSRV runs on the application server.
[PSRENSRV] ;========================================================================= ; Event notification server settings ;========================================================================= ; REN Server log trace level. Use Error, Warning, Notice, or Debug. log_severity_level=Warning ; REN Server buffer size for HTTP output. Must not exceed 65536. io_buffer_size=8192 ; REN Servers place these values in the database when creating ; out-of-the-box initialization parameters. ; If commented out, the values "7180" and "peoplesoft.com" are used. default_http_port=7180 default_auth_token=nextel.com
Pinging the REN Server is a validation that everything went okay with your setup. If it did not, you are SOL and need to do some debugging.