Can you have API mode at the coordinator, and transparent mode at the end devices?
I tried sending an API message to the device. Frame type = 0x10, frame ID = 1, 64 bit address = destination address (end device), 16 bit destination network address is 0xFFFE. broadcast radius = 0 (max hops), options = 0, and the rest of the packet filled with the data.
I’m just not clear if that’s the right way, or do I have to send some other ind of message, like a ZDO message to 0xE8 (then what cluster ID, what profile id?)
Most definitely - the nodes DO NOT move API-frames over the air. The API message just allows you to explicitly control MORE of the actual over-the-air packet.
In AT mode, the over-the-air packet uses defaults and some things hard-coded as setting (such as the DH/DL settings).