Can Nagios monitor a local comm port ? I will need to send serial data to the comm port and monitor the resulting response. If this is not possible can Nagios transfer data from a flat file on the client PC to the host Nagios system?
Nagios itself cannot. Nagios can run a plugin that can. Assuming you know enough about comm port interactions you can write a plugin to do what you need. Check out nagiosplug.sourceforge.net/ to get started.