Xbee Module looses connection after wake-up


I am using my XBEE-Pro module with an arduino hardware and Pin 9 to set the XBee to slee mode.

After powering on, I am waiting for about 15 seconds until the AI LED begins to blink. I transmit the data and send the XBee to sleep. After waking it up I can not send the data immediately. The AI Led blinks 3 or 4 times after waking up and than gets steady. I have to wait for at least 10 secs until the Xbee device has found it’s coordinator again and than I am able to transmit my data.

I’ve read in the documentation, that I could wake up the module, wait for about 10msec and than it should be possible to send the data.

What am I doing wrong? Why does my Xbee module loose the connection after waking up?

Thank you for an hint,

Make sure the parent’s SN/Sp are large enough to accommidate the sleeping child’s absence from the air waves.

Without going too far into the theory, a parent NEVER sends a message to a sleeper - the sleeper ‘polls’ the parent in order to PULL the message. So when you send a message to a sleeping end-devcie, the parent just buffers it wheither the child is awake or sleeping.

The problem is the default SN/SP in a parent is like 320msec, meaning in 3 times that (about 1 second) the parent has disowned the child & discarded any buffered messages, so when the child (your Arduino) wakes and tries to poll (“beacon”) the parent for work, the parent rejects it as an alien. :slight_smile:

I frequently set SN/SP to about an hour (the manual explains the math). But set a reasonable value based on how often you plan to wake the Arduino.

Hi Lynn,

thank you for your answer. But I do not understand, if the SN and SP values are really necessary for me. I am using the PIN Hibernation Mode to wake up the Xbee from my Arduino.

My understanding is, that the Xbee should wake up within a second and has it’s connection back with the coordinator as it had before going to sleep. The SN/SP are for Cyclic Sleeps Configuration only, if I am correct?

Best Regards

Lynn thank you. Got it running. Have set the SN and SP values in the coordinator and it works well now. It took a little bit for me to understand :slight_smile: