ok...

[user at domain.invalid]

I have written a script that read serial port (under linux). This
is done as per user specified interval. So we have,

    while True:
      readport()
      processreading()
      alertusers()
      sleep(nseconds)


(the actuall code is more detailed)

I am currently thinking about reading the port and sending alerts
to users as part of a self test. What I am looking for is to specify a
date and time to run the self tests without interfering with anything
else i.e. the rest of the logic is not affected. Is this possible?

P.S. Cron can probably do the job, but I am trying to stick to python.