I'm working with the ZigBee Mesh Kit, the firmware I think is updated to the latest version, 405F right now.
The SP value is 0x7D0 and the SN value is 30, which, if I understood it well, means an expected sleep time of 16 minutes. The ST time in the end device I don't know, but the datasheet says that it is 15 minutes. This is the datasheet of the device: http://www.develcoproducts.com/media/1826/motion-sensor-technical-manual.pdf
Reading the XBee RF manual, I've understood that the Child Poll Timeout (3*SN*SP) must be higher than the sleeping time of the device, is that right?