Electronic Alarms and Home Security Devices - Double Window contacts

Forgive my obvious ignorance, but I have a DSC WLS925 wireless sensor that protects a pair of side-by-side windows. There are two magnetic switches, one for each window. I expected the contacts to be connected in series, but in fact there is just one wire running to each magnetic switch; i.e., the red wire from the into one and the black wire into the other. Is the WLS925 supposed to detect the slight change in resistence when the contact is closed? Or should there be a third wire connecting the two switches to put them in series?

I haven't been able to get this sensor working again after installing a new panel (DSC PC1555) so I am considering replacing the WLS925, but I need to protect both windows and don't see one sold off the shelf with two contacts.

Thanks as always for any advice.

Take a close look at the wiring. There is probably a wire connecting between the contacts, and they simply fished it inside the window framing.

External contacts are a standard way of dealing with pairs of windows like that. They don't come with the transmitter, they are just a standard wired alarm contact.

A simple test, simply put a jumper wire in place of the contact wiring. If the zone closes you are good, and may have a bad external contact, if not you may have programming issues (remember, the battery cover needs to be on for the transmitter to work)

I put a jumper on the wireless unit and it worked fine...no issues with the programming. I'll wire the contacts properly and be back in business.

Thank you!