Child poll timeout

Router and coordinator devices maintain a timestamp for each end device child indicating when the end device sent its last poll request to check for buffered data packets. If an end device does not send a poll request to its parent for a certain period of time, the parent assumes the end device has moved out of range and removes the end device from its child table. This allows routers and coordinators to be responsive to changing network conditions. You can issue the NC command at any time to read the number of remaining (unused) child table entries on a router or coordinator.

Set the child poll timeout with the SP and SN commands. SP and SN should be set such that SP * SN matches the longest expected sleep time of any end devices in the network. The device calculates the actual timeout as (3* SP * SN), with a minimum of 5 seconds. For networks consisting of pin sleep end devices, set the SP and SN values on the coordinator and routers so the SP * SN matches the longest expected sleep period of any pin sleep device. The 3 multiplier ensures the end device will not be removed unless 3 sleep cycles pass without receiving a poll request. You can set the poll timeout up to two months.

Adaptive polling

The PO command determines the regular polling rate. However, if RF data has been recently received by an end device, it is likely that more RF data could be on the way. Therefore, the end device polls at a faster rate, gradually decreasing its adaptive poll rate until polling resumes at the regular rate as defined by the PO command.