This is ser2syslog, a program for reading data from the serial port and forwarding it to syslog. It was created by drastically stripping functionality out of ser2net. The first versions will not be built with configuratbility in mind.

Of course, if you want to be picky, you could probably achieve the same effect with:

cat /dev/ttyS0 | logger -p local7.info -t "some message"

Where files are used unedited, the original ser2net copyright and headers are retained. When files are changed, a ser2syslog copyright has been added.