Hi, it looks like this constant is used only during the first initialization of the node, when the parent_id and the node_id are being written to the node's eeprom, not during normal operation.
I tested a method from another suggestion on this forum, to ask the controller for the last value sent by the node, since if you ask for data it do times out and you could then assume that the gateway was offline or some other network error occurred, but this technique did not work all the time.
I have power outages here that disable the gateway and then the nodes eat up their batteries trying to resend the same message over and over and I would love to find a way to stop this from happening too.