Digi XBee 3 ZigBee User Manual page 319

Over-the-air firmware/file system upgrade process
for Zigbee 3.0
The FOTA upgrade process is based on the Zigbee Cluster Library specifications; ZCL messages are
exchanged between the server and the client using 0x11 explicit addressing API frames with a cluster
ID of 0x0019. All multiple byte values in the ZCL command in the payload must be sent in little endian
byte order for the command to be executed correctly on the remote device.
For the server to receive the required ZDO responses from the client, set
enable the Explicit Rx Indicator frame -
responses regardless of its serial configuration.
FOTA upgrade image file formats
Storage
ZCL OTA messaging
Image Notify
Create the Image Notify request
Query Next Image request
Query Next Image response
Image Block request
Image Block response
Upgrade End request
Upgrade End response
ZCL OTA cluster status codes
Digi XBee® 3 Zigbee® RF Module
0x91. The client automatically generates the necessary
AO (API Options) to 1 to
320
321
321
322
322
324
326
328
330
333
334
337
319