Yep they are pretty simple, on one end you have a python script that listens to syslog messages, when get gets an interesting one it converts into a binary string and sends out over GPOI14.

This goes through an opto coupler

On the other end there a python script listening on GPIO16, it takes a string of binary data, decodes, checks it's valid, then creates a tagged syslog message. Syslog is configured to forward everything onto a central location for folks to monitor.

Hope that makes sense.