Check if a One-Wire sensor is present.

Using Arduino Project Guidance
1

Hi,
I'm working on a project, where I'm using the Onewire libary from OneWire Arduino Library, connecting 1-wire devices (DS18S20, etc) to Teensy.
I'm using multiple DS2401 chips, which are only sending its ID number.
My plan is to connect the chips to monitor switches like this: http://docs.domogik.org/plugin/onewire/0.2/en/_images/ds2401.png

To my question: As the Subject sais, I'm looking for a way to check if a sensor is present. If it is, I would like a boolean to be set to true, if not it should be false. I have tried different approaches, but no luck due to my poor programmingskills.
Is there anyone who have a better skillset than me, that could help me with this? If so, I would be very happy!

Thanks!