Send custom data

Hi,
I wanna send custom data such as the device number or device status with
USRP.Does it mean I should go deeply into something like
tx_stream->send()?Is there any similar example?
Thanks in advance.

Isnt all data, custom data? So the streamer interface is still just
samples, as is the gr-uhd sink’s input port. If you want to send
arbitrary information, you still need to packet-ize and modulate the
information.

Maybe you will find this project relevant:
https://github.com/jmalsbury/pre-cog/wiki

-josh

Maybe I should cast arbitrary object to binary data followed by
simple_framer block and bits_to_symbols block.Is it correct?

I wanna send variables, which depends on the operating environment.
Flowgraph can only send predefined data. So maybe I should directly call
the UHD API. Is it correct? Thanks.