Variable Packet Size
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Jason Reiss.
Thomas HermanssonHi!
As we all know the maximum amount of data a lora packet can transmit is dependent on the datarate. At 915MHz a DR0 package can carry Maximum 11 bytes and at DR4 it is 242 bytes.
If I would need to transmit say 100 bytes to a node – how would I know how to package it to the mosqito server? Is there a way to query the network server of what data rate a node is using right now – or do I need to always only send 11 bytes per message to mosquito in order to be sure that a package can be transmitted to the node.
From my (limited?) understanding – it is not ok to send a message of 100 bytes and then the lora network server will divide it into several smaller packets if the current datarate used by a node limits package size to say 11 bytes.
Kind Regards
Thomas
Jason ReissThe current end-device datarate is provided with the uplink.
Downlink datarates use DR8-DR13 in US915
Response to uplinks using DR0-DR4 in Rx1 use DR10-DR13 which all allow 242 bytes payload.
DR8 allows 53 bytes and is default Rx2 datarate. Rx2 datarate can be set at network server to DR10 and the setting will be transmitted to the end device on OTAA join.