SK615 Residential Wireless "RF" Motion Detector
Is this motion sensor PET Immune
No it is not. It will be triggered by dogs and cats. What you can do to reduce the false alarms is mount the sensor as high as possible so animals walking on floor will be beyond the range of the motion sensor.
Can the SK615 be connected to the SK601 or SK602?
No it cannot. This is “rolling code” technology. The SK602 is older “dip switch” technology and not compatible. The SK615 can be linked to the SK622 and SK626.
If battery is low could it send false signal?
Yes if the battery is low it could send a false signal to anything it has been learned to. When not using the motion detector remove batteries to avoid false signal and to avoid battery leakage.